# AC 20-106: Aircraft Inspection for the General Aviation Aircraft Owner

- Type: Advisory circular (guidance, not mandatory unless a rule or AD requires it)
- Status: Current
- Approved: April 1, 1978
- Last reviewed: March 31, 2004
- Family: AC 20-106
- 14 CFR parts: 91, 43
- 14 CFR sections: [91.171](https://www.ecfr.gov/current/title-14/section-91.171), [91.169](https://www.ecfr.gov/current/title-14/section-91.169), [91.217](https://www.ecfr.gov/current/title-14/section-91.217)
- Pages: 92
- PDF: https://openairdocs.org/files/sha256/c1/79/c179e30fa7e74b894d6527fc147a20b49d7e05672c576352de13d7c930965997
- FAA DRS: https://drs.faa.gov/browse/excelExternalWindow/33172CD8A28FD290862569BD00687151.0001
- DRS record last changed: November 21, 2025
- Page: https://openairdocs.org/ac/20-106

## Versions

- [AC 20-106](https://openairdocs.org/ac/20-106) (Current), approved Apr 1, 1978, 92 pages

## ADs that cite it (1)

- [AD 2020-16-15](https://openairdocs.org/ad/2020-16-15): Fuselage · Viking Air DHC-2 Mk.I and DHC-2 Mk.III with STC SA00299NY or SA945NE. Effective Sep 21, 2020

## Text

Each page's text from the PDF; open the PDF at a page with #page=N.

### Page 1

AC 20-106

**AIRCRAFT INSPECTION FOR THE GENERAL**

**AVIATION AIRCRAFT OWNER . .**

~~- . • APRIL 1978 U.S. DEPARTMENT OF TRANSPORTATION

FEDERAL AVIATION ADM IN ISTRATION flight Standards Service For sale by the Superintendent of Documents , U.S. Government Printing Office Washington, D.C. 20402

### Page 2

PREFACE The inspecti ons described in this Aircraft Inspe ction hand book are NOT intended to replace any required insp ection. Rathe r, they are intended to familiarize persons with the techniques generally applicable to aircraft in­ spections whether they be owners, pilots, stude nt mechanics, or others with aviation inter ests.

The services of an appropriately rated certificated repair station, certifi­ cated mechani c, or the manufacturer must be utilized for all required inspec­ tions and whenever any inspection reveals a questionable condition. ''T e emphasize the fact that reliable inspection capability comes only with ex­ perience, and the use of this handbook does NOT qualify an individua l to make final airworthiness determinations.

PART I-INSPECTION FUNDAMENTALS Inspection requirements, owner's responsibilities, inspection time inter­ vals, and sources of basic information are discussed in Part I.

PART II-INSPECTION TECHNIQUES The general techniques used to inspect an t>.ircraft are discussed in Part IT.

To facilitat e reference, in the explanation of important inspection pro­ cesses, arrows appear on many of the illustration $. These indicate either the item or the general area to which the tex t refers.

Numerous illustrations are used to convey informat ion to the reader in the most clear, graphic, and effective manner.

Acknowledgment of cooperation is extended to the following:

Beech Aircraf t Corporation Cessna Aircraft Company Cessna Aircraft Company Aircraft Radio and Cont rol Division Edo Corporation Piper Aircraft Corporation Rockwell International (Rockwell Commander Aircraft) The Bendix Corporation Electric /Fluid Power Division The Goodyear Tire and Rubber Company This publication cancels the Personal Aircraft Inspection Handbook, AC 20-9, published in 1964. Suggest ions for revision and improvement of this handbook are encouraged and may be forwarded to Dep artme nt of Transpor­ tation, Feder al Aviation Administration, Flight Standards National Field Office, AFS-5 00, P.O. Box 25082, Oklahoma City, Oklahoma 73125.

i

### Page 3

**AIRCRAFT INSPECTION FOR THE GENERAL**

AVIATION AIRCRAFT OWNER Contents Page Preface -------------- ---- --- ------ ------ --- ------ ---- ------ --- --- i Part I. Inspection Fundamentals - ---------------------------------- 1 Section 1. The Inspection Process ------- ----- ----- ---- ------- 1 Section 2. Prev entive Maintenance --------------------------- 4 Section 3. The F orces o:f Attrition ----- ----- - ----------- --- --- 7 Section 4. Inspection Do's and Don'ts --- ------- ------ ------- - 14 Part II. Inspection Techniques __ ________.,:__________________________ 15 Section 1.

Section 2.

Section 3.

Section 4.

Section 5.

Section 6.

Section 7.

Section 8.

Section 9.

Fus elage ------------------------------------------ 15 Cabin-Cockpit - ---- ------- -------------- ---------- 21 Engine Nacelle------ ------- -------- - ----- ------ --- 27 Landing Gear--- --- ------ --- ------ ----- ---- -- ----- 42 Wing-Center Section --- -- ---- - ---------- ---- ---- -- 53 Empennage --- - --- ------- --------- --- ------ ------- 61 Pr~peller ------------------------ - ----- ----- ----- - 66 Radio - --- ---- ----- ---- ------- ---- ---------- --- --- 71 Miscellaneous --- --------------------------- - --- --- 75 Section 10. Preflight Inspection - ------- -------- - ------ - --- ---- 77 Section 11. After Storage - - --- -------- -------- ----- ------ ----- 80 APPENDIX A.

**APPENDIX B.**

**APPENDIX C.**

**APPENDIX D.**

Figure General Safety Precautions --- --- ---- -- ---- ------ 81 Aviation Fuel-Identification and Fueling Proce­ dures - ------ - --------- ------- .- --- -------- ------ 83 Certificate of Registration-Aircraft Eligibility and Application - - - --- ------ ----- ----- -------- - --- -- 85 Certificate of Airworthiness-:..General Information 87 List of Illustrations PART I. Inspection fundamentals Page I-1. Five stresses acting on aircraft ----- ----- ------------- --- ---- 10 Part II. Inspection Techniques Section 1.

1-1. Inspection chart-fuselage --------- --------- -- -- ----- ---- --- 15

1-2. Cracked fuselage structure ------ ------------- ----- ---- --- --- 16 1---3. Cracked former --- ---- --- ----- ------- ------- --- --- ---- - ---- 16

1-4. Distorted fuselage skin --- ---------------------------------- 16

1-5. Deteriorated fuselage :fabric ---- --- - - ------- - - -- -------- - --- 16 111

### Page 4

Figure Page

1-6. External wing bracing attachment checkpoints --------------­ 16

1-7. Proper cable routing --------------------------------------­ 17

1-8. Improper cable routing - -----------------------------------­ 17

1-9. Proper routing of electrical wiring -------------------------­ 17

1-10. Improper routing of electrical wiring -----------------------­ 18

1-11. Leakage from chafed hydraulic line ------------------------­ 18

1-12. Draining fuel tank sump ----------------------------------­ 18

1-13. Doorlock checkpoints--------------------------------------­ 19

1-14. Emergency exit checkpoints ------- - -----------------------­ 19

1-15. Interior aft fu selage (light twin) --------------------------- 20 Section 2.

2--1. Inspection chart-cockpit ------------------------------------ 21

2-2. Inspection chart-cabin - ------------------------------------- 22 2--3. Operational check-fuel tank selector valve ------------------ 22 2--4. Circuit breaker and fuse panel ------------------------------ 23 2--5. Check quantit y hydraulic fluid -------------------------- --- - 23

2-6. Instrumen t panel ---------------- --- ----------------------- 24 2--7. Bellcrank checkpo ints -------- ------ ---------------- ------ -- 24 2--8. Cable rubbing bulkhead - - ---- --- ----------------- --- ------- 24 2--9. Gustlock ---..----------- - ---------------------------------- 25

2-10. Frayed safety belt ----------------------------------------- 25

2-11. Safety harness --------------------------------------------- 25

2-12. Inspection items on seat ---------------------------------- - - 25 Section 3.

3-1. Inspection chart~ngine and nacelle ------------------------ 27

3-2. Inspection chart~ngine ------------ ----------------------- 28

3-3. Fuel strainer checkpoin ts ---------------------------- ------ - 29

3-4. Carburetor inspection points -------------------------------- 29

3-5. Carburetor air filters --------------------------------------- 30

3-6. Intake manifold checkpoint s -------------------------------- 30

3-7. Oil tank inspect ion ----------------------------------------- 30

3-8. Oil quantity check -------- --------- ----------------------- - 31

3-9. Satisfactory oil line installation ---------------- ---------- - - - 31

3-10. Unsatisfactory oil line installation -------------------------- 31

3-11. Oil-cooler checkpoints -------------------------------------- 32

3-12. Checking sparkplug torque --------------------------------- 32

3-13. Unsatisfactory sparkplug cigarette -------------------------- 33

3-14. Igniter plug-gas turbine engine ---------------------------- 33

3-15. Exhaust manif old checkpoints ------------------------------ 33

3-16. Exhaust stack damage - ------------------------------------ 34

3-17. Heat exchanger-shroud removed ---------------------------- 35

3-18. Cowl flap checkpoints --------- ----------------------------- 36

3-19. Engine baffies ---------------------------------------------- 37

3-20. Engine mount checkpoin ts ---------------------------------- 37

3-21. Cracked engine mount ----- --- ---- - --------------- - - - - ----- - 37

3-22. Checking starter security ----------------------- ----- ------- 38

3-23. Inspect cowling for damage -------------------------------- 39

3-24. Damaged cowling ------------------------------------------ 38 iv

### Page 5

Figure Page

3-25. Rep aired cowling ------------------------------------------ 39 3--26. Cowling installation checkpoint s ---------------------------- 40

3-27. E vidence of chafing ---------------------------------------- 41

3-28. Battery installation checkpoints ---- - --- --------------------- 41 Section 4.

4-1. Example s of tire defects ------ - ----- -- --- ---- --------------- 42 4--2.. Tire prot ected by d:rip pan --------------- - ------------------ 42

4-3. Multiple disc-type brake'------------------------------------ 43

4-4. Shoe and drum-type brake----,--------------------,---------- 43

4-5. Expander block-type brak e --------------------------------- 43 4--6. Disc brake inspection points -------------------------------- 43

4-7. \Yheel and brake inspection points -------------------------- 44

4-8. Hydraulic brake line checkpoints -------------------- -- --- - -- 44

4-9. Simple master cylinder brake systems ------------- --- ----- - -- 44

4-10. Cockpit-hydraulic brake line checkpoint s -------------------- 44 4-11 . Wbeel checkpoints - --- --- ----- ----- -------- ------ - - ------- - 45 4--12. Inspection chart-fixed landing- gear -------- ---- - --- -- -------- 45

4-13. Fixed nose ~ear checkpoints ------------ --- --------------- -- 46 4--14. Oleo-type landing gear checkpoints -------------------------- 46

4-15. Steerable tailwheel inspection points ------------------------ 47 4-16 . Inspection chart-retractable landing gear ----------------- - -- 48

4-17. Retrac table main gear checkpoints -------- --- -- - ------------ 47 4--18. Landing gear retracting - ----- --- --- ----- ----- ---------- - --- 49 4--19. Retractable nose gear checkpoints --- --- ----- - - -- -- - ------ - -- 50 4-20 . Retractin g mechanism checkpoint s - - --- --- ------ --- ------ --- 50

4-21. Typical electrical retraction installation ---- - ---- ----- ----- --- 50 4--22. Electrical retracting motor and wiring ---- ----- ----- ----- --- 51

4-23. \Varning microswitch installation - --- --- -------- ------------- 51

4-24. Gear attachment structure checkpoints --- - ---- - ---------- --- 51 4--25. Float installation inspection points - - - --- - ---- - - ---- ----- ---- 51 4--26. Ski installation inspection points - --- - ---- --- ---- - -- ----- - --- 52 Section 5.

5-1 . Inspection chart-win g-center section - - ---------- - - --- -------- 53

5-2. Indication of defective fabric------- ------ - -------------- - -- 54

5-3. \Vood structure inspection points-- --- ------ -- - --- ----------- 54

5-4. Metal structure inspection points --- - - --- - -- -------------- -- - 55

5-5. Lighting damage-flap, lo,ver surface ----- ------- - ---- ----- - -- 56

5-6. Control bellcrank checkpoints ----- -- ---- ----- ----------- -- -- 55

5-7. Fuel tank vent ----- - -- --- ---------- -------- - - ------ - ------- 57

5-8. Fuel cap, vent, and placard---- - -------- ----- - ----------- -- ­ 57

5-9. Pitot mast, airspeed ------ - ------- ------ --- --------- ------ - ­ 58

5-10. Electrical wiring, proper routing ---- - -------------- - ---- -- -­ 58

5-11. Satisfactory leading edge of wing --------- ----- ---- ----- ---­ 58

5-12. Dented leading edge of wing -------- --- ------ --- -----------­ 59

5-13. Damaged landing light lens --- ----- - --------------- ------ - ­ 60

5-14. Deicer boot damage ------ - - ----- ------ -------- - - ------- ---­ 60

5-15. Block type gust lock ----- - ---- ------------- --- - -------- ---- 60 v

### Page 6

Figur e Page Section 6.

6-1. Inspection chart--empennage ------------------------------­ 61

6-2. Oilcanning of metal skin ---- - ----------------- - -----------­ 62

6-3. External bracing checkpoints --------------- -- -------------­ 63

6-4. Rudder checkpoint s _----- ----'------- - -- -------------------­ 63 646-5. Rudder quadrant . - ---------- - -----------------------------­Stabilizer adjuster checkpoints _________.;.____________________6-6. 65

6-7. Position light checkpo ints _____ ----------------------------- 65 Section 7.

7-1. Inspection chart-propeller--------------------------------- 66

7-2. Damaged metal blade ---- --- ------- --- ------ -- ------- - ----- 66

7-3. Three-blade prop eller checkpoints------------- - ---------- - -- 67

7-4. Propeller tip dama ge ----- - -------------------------------- 68

7-5. ·wood propeller blade-crack ed and separated lamination ------ 68

7-6. Propeller governor checkpoints ------------- ~-- ------- -- ---- 69

7-7. Propeller spinner checkpo int s ------------------------------- 69 7--8. Propeller liqui d anti-icing system checkpoints----------.,.----- 70

7-9. Propeller electrical deicing system checkpoints---------------- 70 Section 8.

8-1. Inspection chart-rad io ------------------------------------ 71

8-2. Communication / navigation equ ipment installation checkpoints _ 71

8-3. Bonding radio equipment to shock mount --- -- - ------- -- ----- 72

8-4. Communi catio n/ navigation equ ipmen t shock moun t ---- --- ---- 72

8-5. Typical communication / navigation equipment cont rol --- --- - -- 72

8-6. Antenna insta llations checkpoints ---- ----- --- ---- ----- --- - -- 73

8-7. ADF antenna-internal loop-tail mount - -- - ---- ------ ----- --- 73 8--8. ADF antenna-fixed loop -- ------ --- -- - --- -- - ------ ---- ---- 73

8-9. Bondin g wires and trailing edge static wicks - -- ------- ------- 74 Section 9.

9-1. Rotating beacon installation --- - ----- ---- - - ----------------- 75

9-2. Autopilot control panel---- --- ----- ---- ------- ----- ---- - - - -- 75

9-3. Emergency locator transmitter-remote mount -- --------- -- -- 75

9-4. Emergency locator transmitter-portable mount ---------- - -- - 76 Section 10.

10-1. Inspection chart-pr eflight 77 Section 11.

11-1 . Bird's nest --- ------------- --- - ----- ---- ----------- --- - ---- 80

### Page 7

Part I. INSPECTION FUNDAMENTALS Section 1. THE INSPECTION PROCESS The Required Aircraft Inspections The Federal Aviation Regulations (FARs) require the inspection of all civil aircraft at specific intervals, to assure that the aircraft's condition is equal to its original or properly altered condition with regard to aerodynamic function, str:uctural strength, and resistance to vibration.

Inspection interval requirements are estab­ lished considering the purpose for which the aircraft is used and its operating environment.

Some aircraft must be inspected each 100 hours of time in service while others must be in­ spected only once each 12 calendar months.

The 100-hour and annual inspections require complete inspection of the aircraft at one time and a certification as to its airworthiness.

Some airplane s may be inspected in accordance with a progres sive inspection (FAR 91.171) or an approved inspection program (FAR 91.217) wherein portions of the aircraft are inspected according to a predetermined schedule.

The inspection requirements for aircraft, in various types of operation, are stated in FAR 91, Section s 91.169, 91.171, or Subpart D of FAR 91. The latter prescribes an inspection program for large and turbine-powered multi­ engine airplanes (turbojet and turboprop). If you are concerned with the inspection of a large airplane (over 12,500 pounds) or a turbo­ jet or turbopropel~er-powered multiengine air­ plane, you should determine the inspection requirements for that specific airplane.

The information contained in Section I of this handbook may not be directly applicable to these larger type airplanes, but the inspec­ tion techniques will be similar.

FAR 91-General Operating and Flight Rules.

Subpart C of Part 91 prescribes rules gov­ erning the maintenance, preventive mainte­ nance, and alteration o£ U.S. registered civil aircraft operated within or outside the United States. (Inspection is part of maintenance.)

FAR 43-Maintenance, Preventive Maintenance, Rebuilding, and Alteration, prescribes rules gov­ erning the maintenance, preventive mainte­ nance, rebuilding, and alteration of aircraft as well as standards for their performance.

Inspection.

Inspection is the critical visual exammmg, testing, measuring, and functional checking re­ quired to determine the airworthiness of the items being inspected.

NOTE; As n!('ntioned in the pref ace, the serv­ ices of a certificated repair station, certificated mecha nic, or the manufacturer must be utilized for all required inspection s and whenever any inspection reveals a questionable condition .

Scope of Inspections.

Aircraft inspection may range from a casual "walk-around" to a detailed inspection involv­ ing complete disassembly and the use of com­ plex inspection aids. The inspections des_cribed in this advisory circular can be made without disturbing the assembly of the aircraft except for the removal of inspection access covers, fairings, and removable cowlings.

The Habit of Inspection.

Tlie inspection of your aircraft should be­ come a habit. To establi sh the habit, begin by performing preflight inspections and work up to detailed inspections. USE the MANUF AC­ TURER'S RECOMMENDATIONS and this handbook as a guide. Develop a system of 1 319-4 70 0 - 80 - 2

### Page 8

inspection and use. an inspection checklist that covers the complete aircraft. Once adopted, you should not deviate from the procedure.

After completing a few inspections you will be surprised at how familiar you will be with your aircraft.

Inspection Intervals and Systems.

Federal Aviation Regulations require inspec­ tion of aircraft at specific intervals and that they be approved for return to service by cer­ tificated and appropriately rated personnel.

The purpose of this handbook is to familiarize interested persons with general inspection tech­ niques and to assist pilots and owners in estab­ lishing an inspection program which will supplement but NOT replace the required inspections.

The interval of your inspection should be adjusted to provide the greatest value to you considering your aircraft use and the required inspections; e.g., if you are required to have 100-hour inspections, you might want to in­ spect the aircraft each 25 and 50 hours. If you are required to have only annual inspections, you may wish to inspect the aircraft each 50 to 100 hours of operation. The manufacturer's service instructions will be valuable in estab­ lishing these intervals.

Historically, inspection intervals have been established on the basis of flying hours. How­ ever, if utilization is low and flying is done over the weekends, you may find it advisable to inspect a small group of items each weekend.

This will spread your inspection over a period of time and reduce large demands on your time. Here are some examples of types of inspection intervals :

By hours:

Daily preflight inspection Powerplant (including propeller and engine controls)-every 25 hours Flight control systems-every 25 hours Landing gear-every" 50 hours Cabin or cockpit-every 75 hours Covering (fabric or metal)-every 100 l1ours Fuselage interior-every 100 hours, etc.

By calendar weeks (eight-week cycle) :

Daily preflight inspection (including propel· ler and engine controls) Powerplant-first and fifth weekend Flight control system-second and sixth weekend Landing gear-third and seventh weekend Cabin or cockpit-fomth and eighth week­ end Covering (fabric or metal)-eighth weekend Fuselage interior-eighth weekend This weekly inspection schedule will provide a complete aircraft inspection every eight weeks. You may wish to extend or shorten this inspection cycle.

In some cases, it may be convenient to estab­ lish a combination of both methods. Regard- .

less of the method chosen, adhere to it faithfully. Do not assume that an item is in good condition. Make a personal inspection each time an inspection is due, according to your plan . There are many inspection items;

each of which is essential.

"When developing an inspection schedule for your aircraft, 'consideration should be given to climatic conditions, frequency and type of flight operation conducted, contemplated pe­ riods of inactivity, and type of storage facili­ ties. A thorough review of the aircraft manufacturer's service instructions will provide many helpful suggestions on inspections. Most manufacturers provide an inspection schedule for their aircraft which can be segmented as you desire. The information in this handbook will not tell you WHEN to inspect. It will suggest WHAT should be inspected and HOW and WHERE to look for possible defects.

Be sure your plans include the time neces­ sary to regularly inspect your aircraft. If such time cannot be included 'in your plans, then you should have it done by certificated personnel.

"'When you have inspections conducted by a professional, whether they are required or sup­ plemental in nature, you should specify exactly what inspection is to be accomplished and re­ quire the person conducting the inspection to furnish a written statement of the results.

### Page 9

Aircraft Logs.

"Logst as commonly used, is an inclusive term which applies to the aircraft record "books/' and to all supplemental records con­ cerning the aircraft. These logs and records provide a history of maintenance and opera­ tion, a control for inspection schedules, data needed to properly accomplish time replace­ ments of components or accessories, and a record of Airworthiness Directive compliance.

Most Airworthiness Directive compliance is based on aircraft time-in-service, and it is a regulatory requirement that records be kept up-to-date.

Tools of Inspection.

The tools of inspection are many and varied.

They range from a pocket-sized magnifying glass to a complex X-ray machine. The tools required to make a simple inspection, of the type which may be performed by the aircraft owner, are inexpensive and readily available.

The following list is typical:

eight or ten-power magnifying glass inspection mirror flashlight small wire brush dull-bladed knife round bristle brush and cleaning fluid (use caution when selecting cleaning fluids) hydrometer some rags small kit of common handtools (screwdriver, end wrenches, diagonal cutters, etc.)

skid-proof stepladder and wheel jacks

REMEMBER If defects are noted or suspected, have a detailed inspection done by a certificated repair station or certificated mechanic.

### Page 10

Section 2. PREVENTIVE MAINTENANCE Preventive maintenance means simple preser­ vation and the replacement of small standard parts not involving complex assemblies. It is corrective action taken before it becomes neces­ sary to make more complex repairs. The following preventive maintenance may be ac­ com:plished by a certificated pilot, who is the owner or operator of an aircraft, not used in . . .a1r earner serv1ce.

This list comes from FAR 43, Appendix A , Major Alterations, Major Eepairs, and Preven­ tive Maintenance, paragraph (c). It reads as follows:

" (c) Preventive maintenance. \Vork of the following type is preventive maintenance:

(1) Removal, installation, and repair of landing gear tires.

(2) Replacing elastic shock absorber cords on landing gear.

(3) Servicing landing gear shock struts by adding oil, air, or both.

(4) Servicing landing gear wheel bearings, such as cleaning and greasing.

(5) Replacing defective safety wiring or cotter keys.

(6) Lubrication not requiring disassembly other than removal of nonstructural items such as cover plates, cowlings, and fairings.

(7) Making simple fabric patches not re­ quiring rib stitching or the removal of structural parts or control surfaces.

(8) Replenishing hydraulic fluid in the hydraulic reservoir.

(9) Refinishing decorative coating of fuse­ lage, wings, tail group surfaces (ex­ cluding balanced control surfaces), fairings, cowling, landing gear, cabin, or cockpit interior when removal or dis­ assembly of any primary structure or operating system is not required.

(10) Applying preservative or protective material to components where no dis­ assembly of any primary structure or operating system is involved and where such coating is not prohibited or is not contrary to good practices.

(11) Repairing upholstery and decorative furnishings of the cabin or cockpit in­ terior when the repairing does not re­ quire disassembly of any primary structure or operating system or inter­ fere with an operating system or affect primary structure of the aircraft.

(12) Making small simple repairs to fair­ ings, nonstructural cover plates, cowl­ ings , and small patches and reinforce­ ments not changing the contour so as to interfere with proper airflow.

(13) Replacing side windows where ,that work does not interfere with the struc­ ture or any operating system such as controls, electrical equipment, etc.

(14) Replacing safety belts.

(15) Replacing seats or seat parts with re­ placement parts approved for the air­ craft, not involving disassembly of any primary structure or operating system.

(16) Troubleshooting and repairing broken circuits in landing light wiring circuits.

(17) Replacing bulbs, reflectors, and lenses of position and landing lights.

(18) Replacing wheels and skis where no weight and balance computation is in­ volved.

(19) Replacing any cowling not requmng removal of the propeller or disconnec­ tion of flight controls.

### Page 11

(20) Replacing or cleaning spark plugs and setting of spark plug gap clearance .

(21) Replacing any hose connection except hydraulic connections.

(22) Replacing prefabricated fuelline!i .

(23) Cleaning fuel and oil strainers .

(24) Replacing batteries and checking fluid level and specific gravity .

(25) Removing and installing glider wings and tail surfaces that are specifically designed for quick removal and instal­ lation and when such removal and in­ stallation can be accomplished by the pilot."

Technical data for use in performing preven­ tive maintenance may be found in the manu ­ facturers' manua ls. General data on aircraft maintenance may be obtained from the follow­ ing Advisory Circulars (AC) published by the FAA. All are available from the Superin­ tendent of Documents (Supt. Docs.) and should be ordered by the stock numbers (SN) listed after each AC.

AC 65-9A , Airframe and Powerplant Meclt.an­ ics General Handbook, is designed as a study manual for persons preparing for a mechanic certificate with airfram e or powerplant ratings .

Empha sis in this volume is on theory and methods of application. It is intended to pro­ vide basic information about principle s and fundamentals common to both the airframe · and powerplant ratings. (S~ 050- 007-00379.­

0.)

AC 65-J2A, Airframe and Powerplant Me­ chanics Powerplant Handbook, is designed to familiarize student mechanics with the con­ struction, theory of repair, operation, and maintenance of aircraft powerplant s and pro­ peller s. (SN 050-007-00373-1.)

AC 65-J SA, Airframe and Powerp#ant Me­ chanics Airframe Handbook, is designed to fa­ miliari ze student mechani cs with construction, theory of repair, opera tions, and maintenance of airframe and airframe systems. (SN 050-007-00391-9.)

Advi sory circulars are available either free from F A.A. or sold by the Superintendent of Documents. The source, ordering instruction s, and current pri ces are listed in t he FAA Ad­ visory Circular Checklist, AC 00- 2. The checklist should be consulted for curren t infor­ mation before placing any orders. (A refer­ ence copy is available at any FAA office or GPO Booksto re.) · The checklist is published three times a year and is available free from Department of Transportation , Publication s Section, ~1-443.1, Washington, D.C. 20590.

The Status of Federal Aviation Regulations, AC 00-44 , is issued as changes require anrl is also availab le free from ·the abo\·e addr ess.

Nlalfuncfion or De#ecl Reports (FAA Form 8330-2) are provided free of c harge and with retum postage paid by the F A.A. They are normally preaddressed when prov ided, and are a convenient means of ensuring that data, re­ quired to make the repo1;t meaningful, is in­ cluded.

These reports are a means by which the aviation community may interchang e service information since the data received on the re­ ports is published in numer ous FAA publica­ tions, available free or on a s ubscription basis.

Malfunction or Defect Report s are also a data SOUJ:<!e used b y the FAA in monitoring the service reliability of a eronautic al products .

'Vhen trends are noted which indicate possible problem areas, the FAA may alert the aviation community or initiate studie s to determ ine the extent and exact nature of the problem.

All aircraft owners, pilots, mechanics, and non-certificated maintenance facilities are in­ vited to participate in the program by submit­ ting M or D ·. Reports whenever they become aware of items that may be of interest to others.

The M or D Reports, FAA Form 8330- 2, may be obtained from most airport managers, main­ tenance facilities, or any FAA District Offic~.

If you have had an experien ce you wish to share, includ e in the report all information available; how the occurren ce became apparent, describe the malfunction , and include model numbers, part number s, and serial numbers .

### Page 12

Parts may be submitted with the report by special arrangement. Pictures, sketches, or snapshots are especially desirable. Include identification . data such as make, model, and assembly name as an attachment rather than printing on the photograph. H you have any questions, or need any help, you~· local FAA District Office will gladly assist you.

The success of the program depends entirely on participation hy the aviation public. If you have comments about the program or have a special experience or a "v,·ould. you believe this'' situation, send them to Federal Aviation Ad­ ministration, Flight Standanls X ational Field Office, Safety Data Branch~ _\.FS-580, P.O.

Box 25082, Oklahoma City, Oklahoma 73125, 6

### Page 13

Section 3. THE FORCES OF ATIRITION A Definition of Attrition.

Attrition, for the purpose of this handbook, is defined as the general wear and tear of an aircraft during its service life. The five basic sources of attrition are: weather, friction, over­ loads, heat, and vibration. These forces assert themselves in many ways on the entire struc­ ture of the aircraft during its life span. Per­ sons making inspections should be familiar with the visible, measurable, or otherwise de­ tectable effects of these forces.

Weather.

Much depends on local conditions such as heat, humidity, rain, wind, and snow. Each element, or combination of elements, has its own peculiar effe~t upon uifferent parts of the aircraft. These effects are discussed briefly in the following paragraphs.

Atmospheric Moisture. The moisture content of the atmosphere is directly related to the severity of oxidation found on an aircraft.

Aircraft based near large bodies of water or in areas receiving heavy rainfall are more sus­ ceptible to oxidation (rusting and corrosion) than those based in. arid areas. Fabric surfaces and wood structures also decay due to at­ mospheric conditions.

Oxidation. This condition is caused by the chemical combination of metal and oxygen.

Oxidation is called rusting when talking about ferrous materials; i.e., steel or iron. The oxi­ dation of copper, aluminum, and other non­ ferrous materials is usually known as corrosion.

Rusting. Rust usually begins as a reddish discoloration on the surface and, if permitted to progress, will result in a reddish brown crustiness on the metal surface. Removal of the crust will probably reveal pitting. If pitted, the part should be examined by an ex­ perienced mechanic qualified to evaluate the extent of the damage and recommend or take corrective action.

The steel tube member s of an aircraft equipped with floats should be given par­ ticularly close ~xamination. It is possible for water to enter the interior of these members, allowing rust to form on the inside of the tubes while the exterior appears to be in good condi­ tion. The best way to check for this condition is to have small holes strategically drilled in the tubing. If water is present, it will run from the holes. It is sometime s desirable to have small pieces cut from critical tube mem­ bers in order to obtain positive knowledge of the condition of the tube interiors .

CAUTION Tests of this ncdure should be performed by, or under the supervision of, a certificated mechanic or repa :r station and entered in the aircraft records. Speciali%ed experience and sk:IJ are required to determine where water is most apt to concentrate, and where and how to drill the tubing.

Rusting may be prevented or retarded by applying a protective coating to prohibit the atmosphere from coming in contact with the bare metal. This is usually accomplished by electrolytic plating or the application of a zinc base paint. Plating may only be accomplished by certificated personnel.

The interior of steel and aluminum struc­ tural tubing is protected by flushing with hot linseed oil, paralketone, or other corrosion in­ hibitors. The holes drilled for this operation are usually plugged with sheet metal screws (see CAUTION above).

Corrosion. Aluminum, magnesium, and other nonferrous metals are susceptible to corrosion whenever the protective coating deteriorates.

Deterioration is accelerated whenever the coat· 7

### Page 14

ing is in contact with an eroding chemical such as battery acid, insecticide, fertilizer or de­ foliant s. Contact between two unpro tected dissimilar metals sets the stage for galvanic action and corrosion, the rate of which in­ creases great ly in the presence of moisture, especially saltwater .

Ordinary corrosion of aluminum, magne­ sium, or aluminum alloy parts can be detected by watching for signs of surface flaking, pit­ ting , or a white or grayish-white powdering.

I:f pitting is apparent. after removing the flakes or powder film, an experienced mechani c should be contacted to evaluate the dama ge. On aluminum and magnes ium (or their alloy s) surface s that have been painted , watch for paint bubbles or blisters. These indi cate cor­ rosion under the paint. The suspected part should be cleaned to the bare metal and exam- .

ined carefully.

Decay of Wood Structure. The protecti ve coating on wood structures usually consists of high grade varni sh or some type of tran spar ent enamel. An acceptable coating w·ill have a hard glossy appearance. ·whene ver and wher­ ever the prot ective coating deteriorat es, decay will start .

Healthy wood will splinter if probed wit h a dull knife point. Decayed wood will crum ble or break away in chunks. vVeathering of the structure· is first indicated by a dull appearing surfa ce, which means that the protecti ve film has broken down. Be especially alert to wooden compo nents subject to the collection of moisture and / or poor ventilation .

Decay of Fabric. The decay of fabric is somewhat similar to the decay of wood. If exposed to the elements, fabric absorb s mois· ture and other harmful substances unles s it is prote cted by several applications of cellulo se nitrate or cellulose acetate, liquid s common ly known :l.S "dope. " vVhen "dope" is applied, it acts to tighten the fabric and produc es a hard , smooth , opaqu e finish. In time , this finish be­ comes brittle and develops crack s which expose the bare fabri c to the harmful effects of ultra­ violet light, dirt , oil, and mildew. The strength of the fabri c decreases to below minimum str •h and is no longer airworthy.

The effect of decay on finishe d fabric sur­ f aces can be ascert ained only by testi ng. To determine if a test is necessar y, examine the fabric surface . If the smface no longer pre­ sent s a hard flexible glossy finish! is severly abraded, or crack fi are present, testing is ap­ propriate.

A manual punc h test, performed by a quali­ fied repair station or mechani c, will p rovide an indication of fabric streng th. .A conclusive tes t can only he done hy a recogn ized test ing labora­ tory, where in fabric samples are tested und er specified tempera ture and humidit y conditions .

If laboratory test facilities are not readily avai lable, contac t );our local FAA inspecto r for information in their regard.

Since re-cover ing a surfa ce is usually an ex­ pensive process, economics dictate s the practice of good preventive maintenanc e. 'Vashing fabric-covered surfaces with mild soap and 'vater, at reasonable int erva ls, will do much to prolong the life of dope a nd fabric. Prote c­ tion from sunli ght also prolong s fabri c lif e, since ultr avio let light is a prime factor in fabric deter ioration .

Friction Friction is described as the resistance to rela­ tive motion between two bodies in conta ct.

Like any machine , the aircraft develops fric ­ tion in hundreds of moving part s. The effect of friction on the aircraft and its components is known as wear. 'Year cannot be prevented, but steps can be taken to deter its ultimat e effects on the aircraft 's airworthi ness by proper lubrication, alignment of moving part s, and cleanliness . To better understand inspection techniq ues, the terms used to describe the var ­ iou s cond iti ons of wear, due to fri ct ion, must be under stood . They are as follow s :

Abrasion is a for m of wear caused by the presence of an abra sive substance between two moving parts. In the fl.igh,t control system, the possibili ty of abrasion can be detected by a gritt y, grindin g sensation noticeable during operation. Landing gear joint s s ubjected to abras ion may exhibit an uneven jerky action .· when in motion. Csually a black gritty sub­ stance will be noti ced at any joint sub jected to abrasion.

### Page 15

Burnishing is the polishing of a surface by sliding contact with another smooth, harder metallic surface. Usually there is no displace­ ment or removal of metal. Burnishing is prob­ ably the least serious of friction-caused prob­ lems; however, it should be very closely monitored. In can be considered a warning of an impending more serious condition-gall­ ing, which is discussed later.

Chafing is the >vear behveen two parts caused by the rubbing, sliding, or bumping of one on the other. The term is normally used to de­ scribe wear between parts not normally in contact. Chafed fabric, wood, or metal can be detected easily since chafing usually marks one or both parts involved. Metal parts, when chafed, show a bright area where contact has been made. Aluminum parts normally display a black or dark gray residue around the point of chafing. The simplest method of inspecting for chafing is to carefully inspect cables, wires, tubes, etc., wherever they are in close proxi­ mity to another part or when they are mounted to permit motion.

Cutting results in cuts or grooves in the worn part. The cause of cutting is similar to chafing except that a sharp edge is in contact, instead of a smooth surface.

Dent is an indentation in a surface produced by an object striking with force. The areas surrounding the indentation 'vill usually be slightly upset. Areas especially susceptible to dent damage are the propeller, spinner, nose contour of engine covding, nose cone of fuse­ lage, and the leading edges of wings, horizontal and vertical stabilizers.

Elongation is the term used to describe the egg-shaped wear of a bearing surface around a bolt, hinge pin, clevis pin, etc. It results in looseness in one plane of motion greater than that o:f the other planes. Flight control sur­ face hinges, engine control rod ends, flight con­ trol push-pull rod ends, bellcrank ends, cable clevis ends, and similar parts are particularly susceptible to this type of wear.

For example, an elevator may have the con­ trol cable rigged so taut that a positive pres­ ::oure is applied on one side of the hinge. Dur­ ing normal operation, the hinge bearing will wear egg-shaped due to the hinge pin rotating under a thrust load imposed by the cable.

Erosion is the loss of metal :from the surface by mechanical action of foreign materials, such as fine sand or water . The eroded area will be rough and may be lined in the direction in which the :foreign material moved relative to the surface. Aircraft operated from unim­ proved airports are particularly susceptible to erosion, primarily on propellers, landing gear, cowling, anrl leading edges of wings and stabilizers.

Galling is the breakdown (or buildup) of metal surface due to excessive friction between two parts having relative motion. Particles of the softer metal are torn loose and "welded" to the harder metal. Galling quite often be­ gins as burnishing.

Gouge. A gouge usually involves material loss but may be largely the displacement of material and results from contact with foreign material under heavy pressure.

ScraJch. A slight tear or break in material surface from light momentary contact with foreign material or object.

Score is a deeper (than scratch) tear or break in metal surface from contact under pressure. It may show discoloration from the temperature produced by friction. The term is normally used to describe conditions on parts designed to run together; i.e., a worn bearing might score the shaft.

Tear is a discontinuity which has progressed through the full thickness of the material.

Overload.

Aircraft are designed to absorb the loads imposed during normal operation and accept a certain amount of overload. Excessive loads, however, result in failure or deformation of the structure. This deformation may be slight or prominent, but it is usually visible. In any case, it can be detected and classified by certain appearances peculiar to the type of overload applied.

### Page 16

In the majority o£ cases, loads which result in deformed ·parts also overload the adjacent structure. Because o£ the possibility o£ hidden damage, a qualified mechanic, repair station, or the aircraft manufacturer should be called Types of forces.

A. Tension C. Torsion Bent structural member E. Bending upon to make a detailed inspection when de­ formation is noted. This is especially true when an aircraft has been in an accident or subjected to suspected overloads on the struc­ ture .

B. Compression D. Shear Tension (outside of bend) FIGURE I -1. Five stresses ading on aircraft.

### Page 17

Tension. 'When a load is applied at either or both ends of an item, tending to pull it apart, it is loaded in tension. Overloads due to ten­ sion usually occur after a hard landing, taxiing on a rough field, or during flight in very tur­ bulent air. After a hard landing, all attach­ ment fittings should be examined for tension failures or deformation. Failure is indicated YJl attachment fittings which show signs of Julling away from fuselag-e structure or failure .n a welded area, and bolt holes 'vhich are elongated or torn. '\Velds are particularly sub­ ject to failure under tension loads and should be closely inspected.

In aircraft of all metal construction, over­ loads are usually evidenced by wrinkling of the metal skin, around wing, stabilizer and landing gear attachment points, and deformed or cracked fittings.

'Ving struts are in tension during normal flight conditions and when severe vertical cur­ rents or gusts are encountered, they may be subjected to heavy loading. The strut attach­ ment points, at the wings and fuselage, should be carefully examined for the indications of failure described for landing gears.

Compression. A part subject to compression loads tends to fail (bulge) at the weakest point in overall length or span, at right angles to the application of the overload.

Compression failures are usually found after a hard landing, flight through turbulent air, or an 'accident, and affects the same areas refer­ enced under tension in the previous paragraphs.

A bulge is indicative o£ compression failure;

however, it is not always noticeable. In this event, a break in protective paint coating may be present. Sheet metal and extruded mem­ bers will show some form of distortion when damaged by compression. In long members such as wing struts, compression may be first evidenced by what appears to be a bow or bend in the member.

A compression overload of a wood member can usually be detected by a slight ridge across the face of the member at right angles to the direction of the grain.

Torsion is a twisting force that tends to turn one end of a part about a longitudinal axis while the other end is held fast or turned in an opposite direction. \Yheels caught in frozen ruts during a landing will tend to twist the landing gear members. Severe air loads im­ posed during abnormal flight maneuvers or flight through turbulent air may twist the con­ trol surfaces or other components. Improper rigging adjustments to wings ancl tail surfaces may also cause twisting of these components.

The inspection, in these cases, is similar to that described for tension and compression over­ loads.

Certain landing gears employ a torsional member referred to as a "scissor," "nut cracker," or "torque link'' Careful inspection should be made of this assembly for loose bolts and cracks, especially after landing in a rough or rutted field.

Shear. An action or stress resulting from forces applied so as to cause a portion of a part to move relatively to another portion in a di­ rection parallel to the direction of the force.

This action is normally found in tools such as bolt cutters or sheet metal shears which apply the force and shear the material being worked.

·when an overload is applied , the part having the least resistance to the force will be the first to fail. For this reason, bolts, rivets, and clevis pins should be examined for signs of failure.

This is especially important when it is found that the overloaded members do not show the usual indications of failure. Failed bolts, clevis pins, and rivets may shear or partially shear and yet appear perfectly normal to the casual observer. To check for this condition~ the following hints may prove useful:

1-Bolts and Olevis Pin.s- Removal and in­ spection is a positive check for condition.

Removal of bolts, clevis pins, etc., is es­ pecially difficult if deformed or otherwise damaged by excessive shear loads.

2-Rivets-Loose or sheared aluminum rivets may be identified by the presence of black oxide which is caused to form rapidly by working of the rivet in its hole. This oxide will seep out from under the rivet head to stain the surrounding surface.

Pressure applied to the skin adjacent to the rivet head will help verify the loos­ ened condition of a rivet.

### Page 18

Bending is a force or combination of forces that will cause a rigid member to curve or bow away from a straight line. Overloads which cause bending are usually the result of ab­ normal landin g and flight loads, or improper ground handling of the aircraft. Bent com­ ponent s will result from the following prac­ tices: stepping or pushing on lift or other struts; lifting the aircraft by the stabilizer ;

jacking or placing suppor ts under longerons;

overloading cabin or baggage compartments;

or exceeding turn limitation s of the nose steer­ ing mechanism. On fabric -covered airplanes, a bent member can often be detected by loose­ ness or 'vrinkling of the fabric. ''"' ood or metal skin may become wrinkled, cracked, or distorted.

Heat .

The principal source of heat affecting the aircraft is the powerplant. From the stand­ point of inspection, we are interested in two heating methods, direct and indirect, both normall y the result of engine operation. Direct heat normally originates from leakin g exhaust gases. Indire ct heat is that radiated from any hot system or component.

Direct hegt. Leaks in components of the ex­ haust system may permit carbon monoxide to enter the cabin heating system. More severe leaks or failures of exhaust system components may allow the escape of flames into surround­ ing areas with disastrou s result s.

To forestall serious hazards, the exhaust pipes, clamps, bolts, braces, and welds should be examined at frequent interva ls. Exhaust gaskets must be in good condition. The nuts holding the exhaust pipe or manifold to the cylinder must be properly torqued and safetied.

Loose exhaust pipe bracing allows the pipe to vibrate, causes failure at the welds, and leaks from the flange surfaces. Heate r muffs or shrouds should be remove~· to allow inspection of the exhaust system component s.

Indirect Heat. Indirect heat radiated or con­ ducted from the engine is carried off by the action of the air stream passing through the cowling. If the air stream is unable to c~rry the heat away , the resulting high temperatures are harmful to the engine and may cause fail­ ure of accessories or other parts of the power­ plant assembly. Excessive indirect heat may be indicated by one or more of the following:

1-High oil temperatu re.

2-High cylinder head temperature .

3-Blistering of the paint covering adjacent parts within the engine compartment.

4-An odor of burned oil or hot rubber dur­ ing or after engine operation.

5-Auto-ignition upon shut down of the en­ gine (engin e tri es to continue function­ ing). .

If any of the above indications are observed, immediate steps s hould be taken to trace the trouble to its source, which is usually loose or leaking engine baffles, improperl y fitted cowl­ ing, improper rigging of carburetor heat door control, dirty oil coolers and screens, impr oper grade of oil, or oil leaks. In any case, once indications of excessive heat are found, a de­ tailed inspection should be made by an appro­ priately rated mechanic or repair station and corrective action taken immediately .

Vibration Vibration is the source of many malfunctions and defects that occur throughout the life ·of the aircraft. Not only will vibration affect parts that are loose or poorly installed , but it will also accelerate wear and cause the ultim ate failure of others. There are two types of vibration in aircraft operation; low frequency and high frequency.

Low frequency (usually noticeabl e vibra­ tion). Low frequency vibration is usuall y caused by a malfunctioning powerplant or propeiler, worn engine mounting pads , loose­ ness of the aircraft structure, or improper rig­ ging. The problem causing vibration should be corrected as soon as discovered since it will cause abnormal wear between moving parts of the .aircraft and may induce failure in any number of other aircraft parts.

### Page 19

High Frequency (less noticeable vibration).

Hig-h frequency vibration is caused by inherent vibration characteristics of the rotating masses in the engine and propeller. It can also be caused by aerodynamic forces acting through the propeller or by engine firing impulses.

High frequency vibrations are usually charted by special instruments at the time the aircraf t is type-certificated by the FAA. \Yh en harm­ ful vibration frequencies are found, placards are installed indicating the engine operating ranges which must be avoided.

Factors of Vibration Damage. The factor s of vibra tion damage can be grouped into three categories: fatigue , excessi ,.e clearance, and poor installation. These point s s hould be con­ sidered when inspecting for the effects of vibrat ion.

fatigue. Fatigue is the weakening and/or eventual failure o:f a member due to the cumu­ lative effects of repetitive loads which cause a change in the molecular strqcture of the part.

Fatigue itself cannot be detected or .measured while it is taking place except, possibly, unde r laboratory conditions. Its effects are usually made known by the ulti mate failure of a part.

The best prevention again st fatigue damage is to maintain a smooth ly running powerplant.

In additio n, control excessive or abnormal looseness in other components of the aircraft by good maintenance practic es, particularl y engin e mounting pad·s which are designed to isolate and absorb vibration.

\Vith the above in mind, it is easily under­ stood why the various components . must be properly mounted and secured to resist the damaging effects of vibration . Copper lines are especially susceptible to fatigue and become hard and brittle when subjected to vibration.

The lines should be periodically replaced or removed and annealed to restore the original softness.

Excessive Clearance. Excessive clear ances ac­ celerate the wear rates of all components in which they exist and cah contribute to the initiation of flutter. Flutter is an aerodynamic function , wherein oscillating high load s are im­ posed on the affected movable surfaces and can result in rapid fati gue failure of critica l areas, such as control surfa ce hinge fittings and at­ tachmen ts. "~ear rate s are extreme ly high during flutter. It is very important to main­ tain clearance within the limit established by the manufacturer.

Installation.

Install ation , as it is used here, is the proper arrangement of the various parts in relation to each other. A fuel.line, for example, may have sufficient clearance relat ive to another part while at rest, yet under vibration, it may move and make contact with the other part and be­ come chafed or cut.

Ignition or electrical cables in contact with each other may appear perfectly rigid during normal operation, but during periods of vibra­ tion they may rub together and wear through the protective casings. Every part of the air­ craft should be carefully examined for signs of chafing or cutting. If vibra tion has gone uncorrected for a time, all nuts, bolts, clamps, etc., should be checked for proper security.

Propeller Vibration Prope llers have inher ent vibration char­ acter istics which are not usually harmful but can indu ce fatigue and in time cause failure of parts essentia l to the airworthiness of the air­ craft. This is one reason why periodic inspec­ tion of the aircraft is essential. .

A special word about propellers. Quite often a propeller blade becomes nicked, es­ pecially at the leading edges. These nicks be­ come points of stress conQentration. IT IS IMPORTANT THAT NICKS BE RE­

MOVED AS SOON AS POSSIBLE AND IN A PROPER MANNER. Since the re­ mova.l of nicks requires special skills and tools and a thorough knowledge of the procedure, such work may be accomplished by cert ificated personnel only. The importance of correct re­ moval of even small nicks AS SOON AS POSSIBLE after incurring them , cannot be overstressed.

### Page 20

Section 4. INSPECTION DO'S DO have an assortment of proper tools for in­ spection .

DO have an i nspect ion check form and a regu ­ lar inspection procedure. STICK TO IT.

DO remov e a ll inspection pla tes and co'v ling s in the area to be inspe cted.

DO clean all items to be inspected: This is es­ sential,in order to clearly see the parts you are inspecting. Inspect before and after clean ing.

DO check all moving parts for proper lubrica ­ tion and check the "jam" or locking nuts on push-pull controls or adjustment de­ vices for security.

DO familiarize yourself with proper sa~etying techniq ues and inspect for proper safety­ ing. Resafety a part you have unsafetied before inspect ing the next item .

DO seek assistance in any questionable area. A certificated mechanic , an approved repair station, or your local FAA inspector are your prime contact s. Use them.

DO'S AND DON'TS DO the job right the first time-save a life­ it may be your O' VN.

DON'TS DOX 'T be hurried - take plenty of time to proper ly inspect each item. If you don~t know what. to do next, ASK .

DOX~T move the propeller unless the ma~neto switch reads "OFF,~' or the ignit ion system is otherw ise rendered inopera­ tive.

DOX'T presume an item is airworthy until it has been checked.

DOX 'T check lan ding gear by kicking it­ raise it off the ground.

DOX'T perform any complex inspection or maint enance operat ion unless you are properly superv ised by a certifica ted mechani c.

DON'T take the attitude -it can~t happen to me.

### Page 21

Part U. ·INSPECTION TECHNIQUES Section 1. FUSELAGE FtcUIIE 1-1. Inspection chart- fuselage.

Before start ing the inspection, be certain that all plates, access doors, and fairings have been opened or remm·ed from the areas to be inspected. ·when opening inspection plates and cowling, take note of any oil or other foreign material accumulation which may offer evi­ dence of fluid leakage or other abnormal con­ dition that should be corrected. M:ake note of these items, then thoroughly clean an areas to be inspected.

Examine the interior fuselage structure through access doors and inspection openings.

Look for bent longerons or braces, cracked tubing or bulkhead s, loose bolts or rivets, and missing safety wire or cotter pins. Carefully inspect the airframe structure using a m~<Tilify· ing glas..<> at the wing, strut, and landing gear attac hment fittings. Look for distQrtion, cracks, poor welds, or elongated bolt holes.

Determine that the entire structure is free from corrosion, rust, deterioration, and other defects.

### Page 22

FIGURE 1-2. Cracked fuselall:e structure.

Frcuu 1-3. Cracked former.

'\Vorn or damaged structure, and component s that are defective, should be repaired or re­ placed by persons authorized in FAR 43, and in accordance with the manufa cturer's instruc­ tions.

Im,pect fabric or skin for tear s, distortion, deterioration, or other defects. Check the con- FIGtJRE 1-5. Deteriorated fuselage fabric.

dition of protective coating. Be sure that the fabric or skin attachment to the structure is satisfactory and that there are no pulled or loose rivets, missing or loose screws, or broken rib lacing.

If the condition of the fabric is questionable, a test should be mad e by a qualified person to determine if the fabric meets the minimum strength requirements.

Check external bracing and attachment fitting s for distortion, cracks, or any other imperfections. Check struts or brace wires for condition and security of attachment. Check FIGURE 1-6. External wing bracing attachment checkpoints.FIGUliE 1-4. Distorted fuselage sldn.

### Page 23

adjustable ends for cracks, excessive bearing wear, worn or damaged threads, loose locking nuts, and any other defects. Damaged brace wires or struts should be repaired or replaced in accordance with the manu£acturer~s instruc­ tions prior to further operation.

Examine control system mechanisms for con­ dition and proper operation. Inspect bell­ cranks for cracks, proper alignment, aQd security. Rotate pulleys to check for flat spots, to provide new bearing surfaces for cables, and to check for smooth, free operation.

Check control rods for security, freedom of movement, abrasion, distortion, corrosion, and proper alignment through formers and bulk- FicURE l-7. Proper cable routing.

FIGURE 1-8. Improper cable routing.

heads. Inspect control rod-ends for cracks, security, e\'idence of misalignment, and exces­ sive clearance in bearings.

Check cables for proper tension and routing through fairleads and pulleys. Control cables should be replaced if damaged, distorted, worn, or conoded, even though the strands are not broken. Control rods s hould be replaced if cracked, gouged, or damaged in any manner other than superficial chafing.

Inspect hydraulic valves, actuators, and boost controls for condition, leaks, security of attach­ ment , freedom of operation, or other defect s.

Particular attention should be given to flexible hoses carrying fluid under pressure.

FrcuRE 1-9. Proper routing of electrical wiring.

### Page 24

FIGUIIE 1-10. Improper routing of electrical wiring.

Check electrical wiring for proper installa­ tion and security of attachment. Check for chafing and general condition. Inspect instal­ lation of grommets, plastic tubing, and con­ nectors. Detennine that soldered electrical connections are not deteriorated or corroded, or that terminals are not weak or misali6Tiled.

Inspect switches, fuses, and circuit breakers for proper condition and rilOunting.

\Viring that has been damaged should be replaced and the cause of damage corrected.

Inspect hydraulic system hoses and metalic fluid lines for leaks, dents, kinks, cracks, chaf- FlctJRE 1-11. Leakage from chafed hydraulic line.

ing, and security. Inspect fluid reservoirs for proper fluid level.

·when leakage cannot be corrected by tighten­ ing connections or replacing packings, a serv­ iceable unit should be installed. Care must be exercised in tightening connections or they may be damaged beyond use.

FIGUIIE 1-12. Draining fuel tank sump.

Inspect fuel tanks and filler caps for proper alignment, security of attachment, and evidence of leaks. Be certain that vents and vent lines are free from obstructions. Examine fuel lines and connections for leaks, cracks, chafing, and security of attachment. Ensure that overflow and drain lines are not kinked or broken, and that they extend beyond the aircraft skin line (overboard).

### Page 25

Fuel systems incorporate fuel tank sumps anrl serliment bowls to trap water that could pass through the fuel lines to the engine.

Periorlically drain fuel from the tank sumps and the sediment bowl, and examine for water or other contamination. Replace anrl safety rlrain plugs.

Tests have shown that, in some cases, rela­ tively large quantities of fuel must be drained before an indication of water is noted. Deter­ mine the characteristics of your aircraft and drain accordingly. The carburetor, fuel lines, anrl tank sumps should be drained, if an ab­ normal amount of water is detected in the main fuel strainers.

FIGURE 1-13. Doorlock checkpoints.

Abnormal water accumulation is reason to suspect the fuel dispensing system of your fuel supplier. He shoulrl be alerterl to the presence of water to permit corrective action.

Inspect cabin and cockpit entrance doors and emergency exits for general condition. Check them for ease of operation and for security of attachment. If the aircraft cabin is pres­ surized, ensure that the door and window seals are intact and in place. Determine that emer­ gency exit placards are clearly legible.

Ensure that thP. doors and emergency exits can be opened from inside the aircraft, and can be positively locked to prevent inadvertent opening during flight. Do not use a seal or r;ealant which 1!Jill prevent operation of eme1'­ gency ewits! Follow the manufacturer's rec­ ommendations exactly.

Examine baggage compartment for general condition. Inspect floor for defects. Check door hinges and locks for condition and satis­ factory operation .

Inspect fuselage or hull for damage and de­ fects, such as corrosion, deterioration, loose rivets and screws. Inspect skin seams for sepa­ ration. Accumulations of liquids should be drained. The presence of any appreciable amount of liquids will affect the aircraft's center of gravity. Be certain that all drain plugs have been reinstalled and sa£etied.

FiGUIIE 1-14. Emergency exit checkpoints.

### Page 26

\Vhenever a panel is removed for interior in­ spection, check the condition of all panel fasteners. Check the opening edges and the panel for cracks. All accessories should be inspected for security and , if movable parts are involved, for freedom of movement. Figure 1-15 shows the interior of the aft fuselage of a light twin. Observe the mounting of the emergency locator tl·ansmitter, "A." and the yaw damper. "B.~' lt) ' - - 20

### Page 27

Section 2.

Inspect cabin and cockpit for general con­ dition~ cleanliness, and presence of loose articles which might interfere with the contro ls or other systems. Using a flashlight, inspect be­ low and behind the instrument panel for loose or chafing wires, instrument line leaks, and any other defect. Check operation of controls for possible interference, full tra vel, abnormal wear, or other defects.

Examine the fire warning and detecting sys­ tem for security of attachment and general CABIN~COCKPIT condition. Ensure that wires connecting the sensing devices and the indicating instrument show no evidence of chafing or deterior ation.

Inspection and maintenan ce of fire exti n­ guishers should be in accordance with the manufacturer~s instructions attached to the ex­ ting uisher unit. Ensure that the extinguisher is fully charged. Inspe ct for general condi­ tion and security of attachm ent.

Inspect the cabin heatin g a nd ventilating system for leakage and condition of units , lines,

2-1. Inspection chart- cockpit.

### Page 28

2-2. Inspection chart - cabin.

and fitting s. Check system operation by mov­ ing the controls to make certain they fun ction properly.

Carefully observe that no flammable mate­ rial is in the vicinity of the heaters and exhaust lines or ports.

FIGURE 2-3. Operational check - fuel tank selector valve.

Check fuel selector valves for leaks, freedom of movement, positive detents , smooth opera­ tion, security of mounting, and placards. Any defects noted should be corrected immediately by a person authorized in FAR 43.

Check engine primer assembly for leaks and operation . Inspect the entire fuel system for general condition, mounting, and freedom from leaks.

Inspect electric wire bundles for general con­ dition , chafing, and routing . Examine con­ nections at terminals, junction boxes, cannon plugs , and clips for looseness and defects.

Check condition of circuit breakers, fuses, switches, voltage regulators, and reverse cur­ rent relays.

Fuse clips (including spares) must be free from corrosion and hold fuses securely, yet permit easy removal. Replace burned out fuses with fuses of proper type and capacity. Re­ place any fuses used from the supply of spare fuses.

Inspect the hydraulic system reservoir for general condition, security of attachment, and proper fluid level. Examine the pressure ac­ cumulator for defects. Check pumps for se­ curity of mounting and condition. Inspect 22

### Page 29

FIGURE 2-4. Circuit breaker and fuse panel.

F:rctJRE 2.5. Check quantity hydraulic fluid.

bypass valves and relief valves for leaks. En­ sure that lines are properly secured and free from leaks, dents, kinks, cracks or chafing.

Check hydraulic brake master cylinder for fluid level and leaks.

Air and dirt in hydraulic systems are the most frequent causes of faulty operation. Air causes faulty release, irregular pressure, and noisy operation. Dirt and grit affect valve op­ eration and produce leakage by cutting the various packings throughout the system.

When repleni~hing hydraulic fluid, NEVER mix dissimilar hydraulic fluids. This "mix­ ing" can result in complete system failure.

Avoid spilling fluid when servicing hydraulic systems since some of these fluids severely damage paints and electrical insulation mate­ rial.

Inspect all instruments for security of at­ tachment, cleanliness, legibility of dial mark­ ings, security of glass dial covers, proper markings, and general appearance. The mag­ netic compass should be checked regularly for proper fluid level and accuracy. Check instru­ ment panel indicating and warning lights for operation, condition, and security. Replace inoperative indicator bulbs. Vacuum lines that 23

### Page 30

~~09® 0 FICl.1RE 2-6. lnstnunent panel.

show signs of deterioration should be replaced. check of vacuum operated instruments is recom­ Inspect the instrument panel for freedom of mended to detect errati c operation . Dirty movement ~nd the shock mount s for signs of filters should be repla ced. Known or suspected deterioration. If the instrument panel is malfunctioning instrum ents should be removed equipped with shock mounts, the panel should and replaced, prior to furt her operation of the nut come in contact with any part of the air­ aircraft.

craft structure, line, or component , rigidl y Inspect all controls linkages for prope r func­ attached to the aircraft structure. tioning and general condition. Check cables When suspected of malfunctioning, the flight for fra yed strand s and proper tension . Ex­ instrum ents should be removed and bench amine pulleys anrl fairl eads for misali gnment, tested by a certified repair station or tested breakage, or looseness. Inspect bellcrank s and with a portable ground test unit . .A periodic torque tubes for alignment, cracks, freedom of movement, and proper safetying. Determine that the pulleys and fairlead s, through which the control cables pass, are clean and that the Fxcuru:; 2-7. Bell crank checkpoints . FxcuR£ 2-8. C able rubbing bulkhead .

### Page 31

surroundin_g structure does not interfere with their movement. Operate the controls to be sure there is no lost motion, binding, or chafing.

I:f inspection reveals that cables or control rods have been chafing against some portion of the structure, they should be realigned. If further inspection reveals the cables or control rods to be worn beyond an acceptable limit, they should be replaced.

FtGURE 2-9. Gustlock.

Inspect gust locks for condition. Ensure that they release completely and cannot inad­ vertently ~ngage.

FiGURE 2cl0. Frayed safety belt.

Safety belts and shoulder harnesses that show evidence of cuts or fraying should be removed and replaced with approved-type belts.

FIGVRE 2-11. Safety harness.

Inspect all safety belt s and shoulder har­ nesses for excessive exposure to the deteriorat­ ing effects of sunrays, acid and dirt. Make certain the latehing devices are in good condi­ tion and operating satifactorily . Ensure that all fitting s and attachment parts are secure and in good condition.

FIGURE 2-12. Inspection items on seat.

### Page 32

Inspect all seats and seat tracks for security of attachment, condition, and function of ad­ justing mechanisms. Floor carpets should be removed to permit inspection of the floor and associated structures to which seat and seat tracks are attached. This is the appropriate time to remove floor access covers and inspect floor substructure, controls, etc., below the floor.

Inspect all windows, windshield, and can­ opies for cracks, cleanliness, freedom of opera­ tion, and general condition. If your aircraft is pressurized, even minor flaws in windows, their attachment s, and operating mechanisms can be critical. If there is any question, ac­ quire the services of a certificated mechanic or repair station, 26

### Page 33

Section 3. ENGINE NACELLE FxcmiE 3-1. Inspection chart- engine and nacelle.

1. FUEL SYSTEM-Look for signs of fuel dye which indicates a fuel leak. Visually check a small amount of fuel in a clear container:

and drain sumps for water .

2. OIL SYSTEM-Check for indication of leaks.

Check oil quantity.

3. EXHAUST SYSTEM-Check for gray-white stains~ which are indications of exhaust leaks at the cylinder head or cracks in stacks.

Check condition of heat muffs for cracks or leaks.

4. COOLING AIR SYSTEM (cowling and baffies) -Check for cracks in cowling and baffies.

Check for proper positioning of baffies, con­ dition of seals, and security of fasteners.

5. INDUCTION AIR SYSTEM (air filter)-Check for proper installation, condition, cleanli­ ness, possible restrictions to airflow, and system air leaks.

6. OTHER SYSTEMS--Check for proper instal­ lation and for cleanliness.

Remove and inspect the fuel strainer screens for damage and water or dirt contamination.

Clean screens, replace, and safety.

'Vhen reassembling the fuel strainer bowl, care must be exercised when tightening the bale wire. Insufficient tightening may result in leakage; excessive pressure may damage the bowl. Be sure trapped air is eliminated, en­ suring unrestricted fuel flow. ·with fuel 27

### Page 34

f '' '' ·· ~ A. Cylinder hold-d own nuts.

B. Crankcase thru-bolts .

C. Fuel inje-ction distributor.

D. Ignition harn ess.

E. Cylinder cooling fins.

F. Firewall.

G. Accessory sect ion .

H. Magnetos.

I. Instrum ent system pressure filter.

J. Oil lines.

K. Cowlin g seals.

FxcuRE 3-2. Inspection chart- engine .

### Page 35

seledor an<l hoo . .-t pump on, cht-ck the fuel st.rainH for leak s. Inspect fuel Jines and con­ nection s for leakage , crack s, kink~. <'hating. and security of mounting_ Examine . hoses and clamps for tightnes~ and condition. Ensur(• that fuel lines do not interferr with adjacent equipment or linrs.

FJcuu; 3-3. Fuel strainer chec1cpoints.

Examine the primer system for general con­ dition and perform an operational check. In· spect for leakage and security of attachment.

Ensure that all conections are tight. Copper primer lines should be periodically annealed to relieve brittleness, by a person authorized by FAR 43.

Inspect the carburetor for general condition, security of attachment, and defects . Inspect for excessive wear at throttle shaft, link as­ semblies, and hot air butterfly shaft. bearing points. Wear can affect the fuel-air mixture resulting in erratic engine operation. Inspect FIGURE :l-4. Carburetor inspection points.

for leaks due to damag ed gaskets, loose fittings.

qr damaged fueol lines. Drain carburetor bow] and examine the ga::;oline for presence of water or other contamination. Remo,·e and clean carburetor screens and inspect for damage.

Flush carburetor by turning fuel supply on momentarily. Replace screens and drain plugs and ensure they are properly safetied.

Remo\'e the carburetor air filter. Clean and inspect. for defect s. Inspect all air ducts for condition , alignment, and security. Reinstal l filter.

Inspect the carburetor air heater for con­ dition and security. Operate the controls through the full travel range. If a question­ able condition is found, contact a certificated repair station, mechanic, or the manufacturer for repairs.

The air filter and air heater are critical in­ spection items. Either can restrict the intake airflow and result in loss of engine power.

Follow manufacturer's instru ctions at all times.

Examine intake manifolds for general con­ dition, cracks, kinks, and evidence of leakage.

Ensure that upper and lower packing nuts are tight and not leaking.

### Page 36

A. Before cleaning. B. Aher cleaning .

. FicUliE 3-5. Carburetor air fiJters.

when replacement s are necessary. Replace­ ment .must done by persons authori zed in FAR 43.

Inspect the oil tan k for evidence of cracks or oil leaks, especially around welded seams FICURF: 3-6. Intalce manifold checlcpoints.

If leaks around the intake pipe packing nut cannot be corrected by tightening the nut, the packing must be repla ced. Use approved parts FiGURE 3-7. Oil tank inspection.

### Page 37

and fittings. Leaks should be traced to their source and corrected.

Check the oil tank retainer straps for evi­ dence of chafing and :for security of attach­ ment. I£ chafing has occurred or the proper security cannot be obtained, antichafe pad replacement is necessary.

FlcuRE 3-8. Oil quantity check.

On wet sump engines, inspect the sump for evidence o:f leaks. Remove oil sump plug and inspect for foreign particles. Remove, inspect, and clean oil sump strainers. Reinstall drain plugs and strainers, and safety immediately.

The presence of metal particles usually indi­ cates an internal failure. It will be necessary to make a thorough internal inspection of the engine which, in most cases, requires a com­ plete engine disassembly. Fill the system with the type and grade of oil recommended by the manufacturer, for the climatic conditions to be encountered.

Inspect oil lines for leakage and security of attachment, particularly at connections. Oil hoses should be inspected for exterior checks F'IcuiiE 3-9. Satisfactory oil line installation.

FlcAAu!. 3-10. Unsatisfactory oil line installation.

### Page 38

and cracks, and proper tension and location of clamps. Any leaks must be repaired immedi­ ately.

FIGURE 3-11. Oil-cooler checkpoints.

If the lubri cation s ystem incorporate s an oil cooler or radiator, examine it very c arefully for l eaks, defects, and securit y of mounting.

Any leaks or defects will require replacement of the unit before further service.

Using a torque wrench, check the tightness of the spark plugs to the torque recommended by the manufacturer.

Examine ignition wiring and connections for general condition. Inspect spark plug barrels, elbows, and knurled nuts for proper tightness.

Inspect shielding and bonding for condition and security.

Periodically inspect spark plug "cigarettes" for cleanliness, cracks, and broken spring con­ tacts. Figure 3-13 shows a burned spark plu.~ cigarette. For maximum efficiency of the igni­ tion system, this spark plug cigarette should be replaced.

CAUTION If your engine is a gas-turbine type, its ignition system is entirely different from that used on re<iprocating engines.

' Work on turbine engine ignition syst ems can result in SEVERE BODILY INJURY OR DEATH due to electrical s hock, Iunl ess you are ful!y familiar with racornmended procedure s.

Figure 3-14 s hows the normal rondition of a gas turb ine ign:tar plug and illu strate s how th ey differ from spark plugs I FIGURE 3-12. Checking sparkplug torque.

### Page 39

FicuRE 3-14. Igniter plug- gas turbine engine.

FIGURE 3-13. Unsatisfactory sparkplug cigarette.

FIGURE 3-15. Exhaust manifold checkpoints .

### Page 40

Be certain that the magneto holddown nuts are tight and properly safetied. If the hold­ down nuts are loose, it will be necessary to check the magneto timing to make sure it has not been disturbed and technical assistance shonhl be sought. Inspect magneto and cover screws for security.

Check magneto ground wires for condition and proper attachment to the magneto terminal and the ignition switch. If the magneto is not properly grounded, it is possible for the engine to operate, even though the magneto switch is in the "OFF'' position. A check of this "OFF" position should be made a regular part of each engine shut down after each flight.

BE\VARE OF THE PROPELLER, even when the switch is "OFF"--especially when the engine is warm.

Inspect each exhaust stack for condition and !>ecurity of attachment. Examine the entire collector ring or manifold for cracks, failure of the joints, or other indications of deteriora­ tion. Check that no portion of the engine cowling has been in contact with the collector ring or stacks. Be certain that all support bolts are tight and safetied.

Inspection of the engine exhaust system should. be thorough to ensure there are no defects that might permit an open flame to enter the engine compartment and present a fire hazard. Exhaust leakage can be identified by flame or smoke "tracks" (gray-white de- A. Tailpipe burned.

B. Exhaust deposits.

FtctJBE 3-16. Exhaust stack damage.

### Page 41

posits) at a break in the system or on the adjacent area where exhaust gases impinge.

Figure s 3-16 sho>YS an exampl e of exhaust outlet damage "~\_'' anrl eviden ce of exhaust deposits "B.~' On turbine engines, check the tailpipe s and trim devices to see that they are not cracked and are in order. Check the controls for free­ dom and alignment. Any binding or malfunc­ tioning of an engine control system should be traced to its source and corrected.

Figures 3-17 shows a heat exchange shroud opened for inspection. Arrows indi cate area s which are prone to failure.

Remove the heater shrourl from the exhaust manifold or mufHer and inspect for cracks , burned- out spot s, or defective welds. Deter­ mine that shutoff valves are operating through their full travel. Ensure cold air and heater ducts are free from obstru ctions and cracks, and are properly secured. If the heater in­ corporates an inten sifier tube inside the ex­ haust ring or manifold , it should be removed and inspected for cracks or burned-out spots.

Defect s noted in the heater system must be repaired or the unit repla ced immediately to assure that carbon monoxide or flames will not enter the cabin or cockpit. When an exhaust FlctlJIE 3-17. Heat exchanger-shroud removed.

### Page 42

FICURE 3-18. Cowl flap checkpoints.

leak is indicated or suspected during flight, open the cabin windows. Turn the cabin heat "OFF" and fresh air ventilation "ON" to avoid carbon monoxide poisoning. Do not use these procedur es to initiate a flight with known exhaust system or heater defects. 0arbon monoxide kill s.

Operation of the cowl flaps is of vital im­ portanc e in keeping cylinder head tempera­ tures within the required operating range .

Determine that cowl flaps are in good con­ dition; the hinge s are not worn beyond limits;

and the actuation mechanism is properly rigged for full travel and is operating properly. Cowl flaps must be maintained in good operating condition at all times in order to obtain re­ quired engine efficiency.

Figur es 3-19 shows example of two types of repairs to engine baffles. "A" is a sheet metal reinfor cement for a broken holddown bolt hole. "B" is a welded repair in a similar area.

Check baffles for security, holes, cracks, and proper fit around the cylinders. Inspect all air entrances and exits for deformations which might obstruct airflow.

Pressurized air is required for engipe cool­ ing; therefore, any leak around or through baffies causes a pressure drop and loss of cool· ing efficiency.

Use a drop light or flashlight to look through the nose cowling and check for gaps between the top cowling and engine baflles.

Inspect engine cylinders for cracked or broken fins.

Some engine mount s are heat-treated and may not be repaired by welding unless nor­ malized and reheat-treat ed to their previous strength values. ·when cracks or inferior welds are found in such units , replacement or repair by the manufacturer or authorized repair facility is necessary. Nonheat-treated engine mounts may be repaired by welding if the work is perform ed in accordance with the manufacturer's instruction s and is done by a person authorized in FAR 43.

### Page 43

A. Sheet metal reinforcement.

B. Welded.

Ftcmu: 3-19. Engine baffles.

FtCUliE 3-20 . Engine mount checkpoints. FiGuliE 3-Zl . Cracked engine JJIOUIIt.

### Page 44

Examin e the entire engme mount structure with a magnifying glass, especially at welds.

Look for evidence of cracks or failure and inferior welds. Ensure that all attachment bolts are tight and properly safetied.

Inspect the mounting of all accessories such as generator, start er, oil pump , oil pressure relief val ve body, etc., for security of attach­ ment, oil leakage, and prop er safet ying. If oil or other fluid is detected around any of the accessories, the unit should be removed and the leakage corr ected.

\Vhen combustion heaters are inst alled , in­ spect for security of mounting and proper in­ stallation of hot and cold air intake ducts.

Inspect fuel lines for condition, leaks, attach­ ment, and freedom from obstructions and kinks.

\Vith heater switch "OX," check the solenoid valve to determine whether it is operating satis­ factor ily. If no clicking can be heard in the solenoid, it should be removed, clean ed, and FlGUIIE 3-22. Checking starter security.

FIGURE 3-24. Damaged cowling.

### Page 45

inspected. Enf>ure that exhaust and on'rflow lines are properly rout ed through the structure to the o utside air.

FlcvJIE 3-23. Inspect cowling for damage.

Inspe ct en~ine cowling for defects such as cracks, dents, chafing on portio ns of the engine or aircraft structure, and loose rivets, clamps, fasteners , or other locking devices.

After completion of cowling repair s, rein­ stall and check for proper fit and security.

The presence of black or dark streaks on aluminum structur e usuall y indicates chafing caused by ,-ibration anll lool;eness.

Che{:k condition of the firewall behind the engine. Inspect in!;u}ation for cond ition, attachme nt, an<l for oil or fuel saturation .

Oil or fuel sa.turation of insulation material present s u serious fire hazard . The source of the oil or fuel must be located and the leak correc ted. The ~ at urated insulation should be removed and cleaned if possible. I:f cleaning is impossible, t he insulati on must be replaced.

FicuBE 3-25. Repaired cowling.

### Page 46

FIGURE 3-26. Cowling installation checkpoints.

Figure 3- 27 show·s the results of improper fit of the engine access cowling. Kote arrow pointing to hole worn in nacelle fairing.

BaHery Maintenance Precautions It is a good practice to prote ct the area adja­ cent to the battery with an acid -proof paint if it is a lead-acid battery , or an alkalin e base paint if it is a nickel-cadmium battery.

"\\"hen working aro und the battery, care should be exerci sed to avoid short- circuitin g across the term inals. Resultant arcing present s a serious fire hazard. As a safety precaut ion, the battery should be removed during cleaning and repair operation s. Remove the "ground" terminal first, and reinstall it last.

Lead-Acid Battery Inspection and Service Check the battery box and terminals for corrosion and security. Inspect vents and overflow lines for condition and obstructions.

These lines should be routed to prevent over­ flowing liquid from conta minating and cor­ roding the adjacent stru cture.

Check the charge of a lead-a cid battery by using a hydrome ter. When the hydrometer test indieates a variance of more than 20 points between cells, the battery should be recharged or replaced.

If the electrolyte in a lead-acid battery is low, repl enish it with distilled water to the specified level. A 30-minute flight should be sufficient operating time befo re conducting a hydr ometer test after refilling.

### Page 47

FIGVRE 3-27. Evidence of chafing.

Nickel - Cadmium Battery Inspection and Service Check the battery box and terminals for cor­ rosion and security. Inspe ct vents and over­ flow lin es for condition and obstructions. These lines s hould be routed to prevent overflowing liq uid from contacti ng and corroding the adja­ cent structure.

Check the individual cell voltages. If an unbalanced cond ition exists, maintenance by a certificated mecha nic or certificated repair sta­ tion is required.

1Vhite powder on top of the battery indi­ cates spillage o£ the electrolyte and requir es the same action as the unbalanced condition .

Maintenance should be done in accordance with the manufacturer's specifications .

'FU;uRE 3-28. Battery installation checkpoints.

### Page 48

Section 4. LANDING GEAR There are numerous types of landing gears:

tripod; spring steel; single strut; fixed and re­ tractable gear for operation on wheels from prepared or semiprepared hard sur~aces; floats for operation from water; and skis for opera­ tion from snow and. ice surfaces. Certain features are common to nearly all wheel-type landing gear and, therefore, will be discussed as one topic to simplify the inspection pro­ cedures.

Tires and wheels absorb the origi nal impact upon landin g and are the princip al part of the aircraft involved in ground control. Fail­ ure of a tire at any time can lead to undesirable Over-inflated Replace Under-inflated Replace circumstances; therefore, tire and wheel inspec­ tion and maintenance are priority items.

Inspec t tires for proper inflation. Use the pressure recommended by the aircraft manu­ facturer. Look for cuts, b ruises , wear, bulges~ imbedded foreign objects, and deterioration.

Excessive tire wear may be caused by misalign­ ment of landing gear wheels, scissors assembly, or axles. If tire s are underinflated, their side­ walls may crac k and show other signs of excessive breakdown. If tube less tires are un­ derinflated, the seal against the rim may leak. Continue Worn out Overinflated tire s may show abnormal crown in service Replace wear.

Unbdanced tire :; and wheels result in uneven FrcuRE 4-L Examples of tire defe(.tS.

tire wear and cause vibration which can, in turn , dama ge other parts of the aircraft. Some tires have a color thread imbedded in the car­ cass. When the tire' s thread wear s to a cer­ tain point, the color tracer indicates that it is time to recap or replace the tire.

If the tire has no color tracer, a tread .worn smooth is usually a signal for similar action.

Petroleum product s can cause rapid dete ­ rioration of rubber in a tire. Do not allow oil or fu el to drip on tires, and avoid parking the aircraft '"here they have been spilled.

FicVRE 4-2. Tire protected by drip pan.

### Page 49

Brakes FlCUJI£ 4-3. Multiple disc-type btake.

FIGURE 4-4. Shoe and drum-type brake.

Jack up the airplane, remove the wheel, and inspect the brake assembly for broken or dis­ torted parts~ broken springs, and worn lining.

Fault y or missing sprin g clips may cause brakes to chatter. Check the condit ion of fric­ tion components (discs~ expanders, and shoes)·.

Examine brakes for security of nuts, bolts, and cotte r pins, Determin e that foot and park ing brake controls are in good condition ~ operating properly, and safetied. Check the antiskid unit s, if installed.

FIGURE 4-5. Expander block-type brake.

FIGURE 4-6. Disc brake inspection points.

.Improper functioning of brakes could cause serious consequences. Any defects or question­ able items noted should be referred to qualified maintenance personnel aut horized in. FAR 43 to make repai rs or adjustments.

### Page 50

FxGVRE 4-7. Wheel and brake inspection points.

"\Vhen mechanical brakes are installed, ex­ amine the cables for condition. vVorn or frayed cables should be replaced. Check pulleys for ease of turning, alignment, and prop er attachment. Check pedals and actuat­ ing arms for proper operation. Check fric­ tion components for condition.

FIGVRE 4-8. Hydraulic brake line checkpoints.

When hydra ulic brakes are installed, inspect fluid lines for defects. Check the system for leakage around wheels, master cylinders, and connections. Inspect for deterioration and security of flexible tubing. Check brake fluid FtcuRE 4-9. Simple master cylinder brake . system.

FicuJIB 4-10. Cockpit-hydraulic brake line checkpoints .

level in the reservoi r. A low fluid level may indicate a leak somewhere in the system, re­ quiring a more thorough inspection of the brake system. Always use the type of brake fluid recommended by the aircraft manufac­ turer . If the brake pedal feels "spongy" when pressed, it may indicate air in the brake system or other abnormality. Further inspection and corrective action is warranted.

### Page 51

Wheels Inspect wheels for damag e and cracks. A bent or distorted wheel flange generally indi­ cates that it is c racked or broken. Inspect bolts for condition and securit y of attac hment.

check the condition of wheel bearing s. With the wheel install ed on the axle) check ex­ cessive side play by moving the -..vheel back and forth against the thrust " ·asher and ad­ justing nut. When prop erly adjusted , safety the retaining nut.

To prevent damage to bearings from the abrasive action of dirt, the hub cap should he installed and secured in position.

Before re-installing wheels, clean, lubricate , and Fixed Landing Gear Shock Absorbers Regardles s of the typ e of l anding gear in­ Ficui\E 4-11. Wheel checkpoints. stalled, a shock absorbing mechanism is profi:cuRE 4-12 . Inspection chart-fixed landing gear.

### Page 52

vided to absorb the landing loads. A number of different shock absorbing devices are used by aircraft manufacturers. A few will be discussed here.

"'When shock cords are employed, inspect for general condition, cleanliness, stretching, and fraying.. Shock cords must be kept free of gasoline and oil, both of which deteriorate rubber products. Follow the manufacturer's recommendations regarding life limits of the replacement of shock cords.

Perform a close visual inspection of the main landing gear for cracks in the vicinity of welds. Examine attachment fittings for condition and elongation of bolt holes.

Wrinkled fabric or metal skin detected in the area of the attachment fittings should be referred to a qualified mechanic or repair sta­ tion for detailed inspection and analysis.

Spring steel shock absorbers require little maintenance. Check for cracks in the fuselage attachment brackets and the axle attachment area. Inspect the strut in the step attachment area.

Excessive play between fittings may be de­ tected more readily if the wheel is off the ground and the landing gear shaken vigorously in a fore and aft direction, as well as up and down. If noticeable clearance is detected at any of the attachment points, the bolts should be removed and inspected for wear or distor­ tion. Defective bolts should be replaced im­ mediately and distorted bushings and fittings repaired or replaced as recommended by the manufacturer. Since there will be considerable movement at the bearing surface, it is essential that they be inspected carefully and lubricated properly at frequent intervals.

Inspect shock struts for cracks, bowing, and security of attachment. Check braces and fittings for general condition and possible defects.

Inspect the nosewheel assembly for general condition and security of attachment. Ex­ amine linkage, trusses, and members for evi­ dence of uHdue wear or distortion. Ensure that all bolts, studs, and nuts are secure with FrGURE 4-13.. Fixed nose gear check points.

no indication of excessive wear and that they are properly safetied. If a shimmy damper is installed , ensure that it is operating satis­ factorily and that the steering mechanism is properly rigged.

FrcUIIE 4-14. Oleo-type landing gear checkpoints.

### Page 53

FxcVRE 4-15. Steerable tailwheel inspection points.

Inspect oleo-type shock absorbers for cleanli­ ness, leaks, cracks, and possible bottoming of the pistons. Check all bearings, bolts, and fitting s for condition, lubri catio n, and proper safetying.

Following the manufa cturer's instruc tions when replenishing fluid and air pressure charge in the shock absorber.

Steerable tail wheels should · be inspected for bearing adjustment, lubri cation, clearance, and range of opera tion. Check for proper steer­ ing action and security of attachment.

Landing gear that retracts into the wing, nacelle, or fuselage structure should be cleaned and checked frequently for defects and prop er operation. Particular attention should be given to locking mechani sms, drag struts, shock strut, stops, linkages , and alignme nt. Be sure the shock strut is properly inflated and the piston is clean and oiled. Examine fairing doors for satisfactory operation, proper rig­ ging , and for loose or broken hinges. FIGURE 4-17. Retractable main gear checkpoints.

### Page 54

Retractable Landing Gear Fzcutt 4-16. Inspection chart-retractable landmg gear.

### Page 55

FtcUIIE 4-18. Landing gear retracting .

·when new or retread tires are installed, a landing gear retraction test should be per­ formed to check for prop er cleara nce. Im­ proper tire size may cause the gear to hang up in the wheel welL Check main gear, nose gear, or tail gear uplo ck and dmvnlock mechani sms for general condition and proper operation.

Refer to the manufact urer's service instruc ­ tions for proper lubrication of retractabl e land­ mg gear.

Inspect the power sources and the retract­ ing mechani sm of the main gear , nose gear or tail gear for general condition, defects, and securit y of atta chment. Determi ne that actuat­ ing cylinders, sprocke ts, universal s, chains , and drive gear s are in good condition and within the nanufa cturer' s toleran ce. Clean and lu­ bricate using- cleaning fluid s and lubricants recommended by the manufacturer of the air­ cra f t.

Inspect the aircraft s truc ture to which the landing gear is attac hed for distortion, cracks, and general condi tion. Be s ure tha t all bolts and rivets are intact and secur e.

Any iten:1s not within r equired tolerances shou ld be referred to qualified maintenance personnel for corre ction and readjustment.

### Page 56

FactiRE 4-19. Retractable nose gear checkpoints.

FxCURE 4-20. Retracting mechaniml checkpoints.

If the landing gear is electrically operated, inspect mot ors for defects and security of attachme nt. Ensure that wirin g is in good condit ion, properly routed, and secured to pre­ vent interfer ence with movable members. De­ termin e that protective rubber or plastic caps are properly install ed over all wire terminal s requiring such prot ection.

FICUBP 4-21. Typical electrical retraction installation.

### Page 57

FtcVRE 4-22.. Electrical retracting motor and wiring.

If the landing gear is hydraulically op­ erated , inspect all actuators for general con­ dition, leakage, and operation throughout their full· travel. Determin e that lines, reserv oirs, accumulator s, and valves are securely at tached ·and free of· leaks. Be cert ain that t he lines are free from chafing and securely attac hed to the adjacent structure. Check entire gear op­ eration, using normal hyd rau lic p ressure.

I nspect warn ing system microswitches for cleanlin ess, condi tion, securit y of atta chment, and prop er operation. With the aircraft on jacks, c heck l andin g gear warnin g horn systern with electrical power "ON," by retarding throttle (s ) wit h ~ar retracted. Check wiring for routing , freedom from chafing, and general conditi on.

Water accumulation in mi cros wi tch~s may freeze at altit ude, making switches inop erative.

Only qualified personnel should attempt any adjustments to the micro switches.

FictJBE 4-24. Gear attaehmeM stru<*lr~ checlcpoints.

Other Geer Inspect the skin f or general conditi on, evi­ dence of corrosion, o r loose rivets and screws.

Check the s t ructure for defects or cracks.

FicURE 4-23. Wa.mmg microswitch installation.

### Page 58

Inspect float attachment fittings for condi ­ tion, crack s, and defective welds. Check struts and bracing for proper attachment, alignment, and safetying. Due to the rigidity of float in­ stallation s, a thorough inspection should be made of the fittings and adjacent structur e where the struts are atta ched . to the fuselag e.

Drain or pump any accumul ated water 'from each float compartment.

Skis should be inspected, for defects or damage and for security of riggi ng a nd main axle atta chment fittings. Specia l attention should be given to the ski pedesta l. Per iod­ ically inspect the ski bottoms for tears or cracks. If installed, check hydraulic system for leaks and proper fluid level. Inspect for conditi on and proper riggin g of all devices restrainin g t he skis from digging into the snow.

Frou1IE 4-26. Ski instaThltion inspection poinbl.

### Page 59

Section 5. WING-CENTER SECTION FicURE 5·1. Inspection chart-wing-center section.

Determine the condition of the wing an.d center section by carefully inspecting fixed surfaces for signs of deterioration, distortion, and loose or missing rivets and screws, espe­ cially in the area of fabric or skin attachment to the structure. Inspect fabric or skin for tears, cuts, or other defects; and examine con­ dition of protective covering. Inspect fabric at windshield for deterioration and security of attachment.

External distortion in any area may be an indication of internal failure. Inspect the in­ terior through available inspection doors or holes. If internal failure is suspected and no inspection doors or holes exist, contact a cer­ tificated maintenance facility to make the neces­ sary inspection and repair.

Inspect the internal brace fittings (struts or brace wires) where they attach to the wing structure, for distortion, cracks, or any other defects. Inspect clevis pins or bolts for wear, cracks, 'vorn or damaged threads, and any other defects.

If any rigging adjustment of the external bracing has been accomplisned, particular care should be taken to ensure that there is a suf­ ficient number of threads holding in the ad­ justing terminals. Most terminals are provided with a test hole in the shank :for making this inspection. If safety wire can be inserted through the test hole, the terminal is not being held by the required number of threads.

Another method of ensuring that sufficient threads have been screwed into the barrel or :female fittings is to count the threads on the 53

### Page 60

male fitting. H more than three threads show, the connection MAY not be satisfactory.

Determine that wing attachment fittings are not distorted, cracked, or damaged in any way, and that bolt holes are not elongated. Check wing attachment bolts for general condition and security of attachment. If wing attach­ ment bolts are loose, determine the reason for looseness. Tighten to the torque values speci­ fied by the manufacturer if no other defect exists.

Be certain that hydraulic lines are free from cracks, kinks, dents, and leaks, and inspect for sec~rity of attachment and wear due to chaf­ ing. Ensure that hydraulic actuators are se­ curely mounted and not leaking.

Any defects noted in the hydraulic system should be corrected. by a properly qualified mechanic.

If the condition of the fabric is doubtful, the advice and assistance of a qualified person should be sought. Samples of the fabric may be taken from portions of the aircraft 1\fOST affected by the elements and forwarded to an accredited testing laboratory for examination.

On fabric-covered surfaces, check drainage grommets for security of attachment and obstructions. Drainage grommets are reinforced openings usually located near the lowest point at the trailing edges of wings and tail sur- FiCUBE 5-2. Indication of defective fabric .

faces. These openings provide for drainage of moisture and circulation of air to dry interior surfaces. Seaplane drainage grommets are identified by a hood over the center cutout which minimizes effect of spray during takeoff and landing. This type of grommet is some­ times used on landplanes in that part of the structure subject to splash from the landing gear when operating from v>et or muddy fields.

\ FicMI& 5-3. Wood structure inspection points.

### Page 61

FIGV:RE 5-4. Metal structure inspection points.

Remove all inspection plates and fairings, and open all access doors so that internal in­ spedion may be made. Examine the internal structure for condition of spars, ribs, com­ pression members, rib lacing, and any internal form of skin attachment. -Inspect spars and ribs for cracks, damage, and deterioration.

Check the condition of glued joints and the protective finish on all internal structure.

Inspect compression members for security, cracks, kinks, bends, and condition of finish.

Inspect drag and antidrag wires for proper tension, attachment, protective coating, and corrosion. Check all fittings attached to spars or ribs for security, protective coating, and corrosion. Check all forms of internal skin attachments for proper security.

Any defect or questionable item in the wing structure should be brought to the attention of qualified maintenance personnel.

Inspect movable surfaces (ailerons, flaps, and trim tabs) for proper operation. Check for loose or pulled rivets, distortion, and loose fabric or skin attachment. Examine hinges and horns for security of attachment, breaks, bends, loose or worn pins, proper lubrication, and safetying.

No repairs, refinishing, or repainting of balanced control surfaces (ailerons, elevators, rudders, and trim tabs) may be accomplished unless the surface is rebalanced. Control im­ balance may cause a dangerous vibration or flutter condition. Rebalancing may only be accomplished by certificated personnel.

FIGURE 5-6. Control bellc:rank checkpoints.

Examine the control mechanism for freedom of movement and proper operation. Inspect bellcranks for cracks, alignment, and security.

Check cables for proper tension, fraying, wear, and proper routing through fairleads and pulleys.

Inspect hinges for breaks, cracks, distortion, and security of attachment.

Refer to the manufacturer's recommended procedures for lubrication.

### Page 62

·t;':~J~~t~ ..:~· ... '~;.. . .::~;' ...... .,... . ·. • . ••,(... .1.11,... ; .....

1 i •·· ..

~ ~ ~ .· . .. ···. .·..·........· .··.·.. ··· ·:•:·•···:::. l.'\'\it\..\\~\l .i~\~\..':\\\l\\·l·:r\'..'.:\t.::,,;.:~:\:;-::_m~;~m; j~=~::i;i~iiii~i~it~~~~rm:i!~:m:Htlli mi~-m~Emlm ~! • : ~ "'""' .

.~ .; .' t · ·· · ,,,,:

·~L ~ .~. .. ,... :.•;:::m·:r :.~;jlimm:.::":.: .. ...

l''tcviiE 5-5. Lightning damage-flap , lower surface.. r

### Page 63

FlGUIIE 5-7. Fuel tank vent .

FICUU 5-8.. Fu(ll cap, vent, and placard.

Inspect fuel tanks for security of mounting and signs of leakage. Ensure that filler caps are secure and the vent is in the prop er loca­ tion and free from obstructions. Check fuel lines and connections for leaks, cracks, security of attachment, and chafing. Be sure overflow and drain lines are not kinked or broken and are properly routed to the outside air.

Improperly placed vent s and line s that are kinked or otherwise distorted can cause "fuel starvation" and engine stoppage . As a pre­ caution against using the wrong grade of fuel , make sure a legible placard is located at or near the fuel tank filler neck.

Inspect pitot tubes or masts for obstructions, distortion, and security. Make sure static vents 57

### Page 64

FICmu: 5-9. Pitot mast, airspeed.

(ports) are clean and free from obstruction.

Periodically, drain and clean. out pitot and static lines. Care must be used to ensure drains are properly closed since leaks have an adverse affect on the accuracy of instrumen ts in the system.

Ensure that wiring is routed so that it can.­ not possibly become entangled with movable mechanisms. Inspect all wiring for chafing, proper installation , and security. Check in­ stallation and condition of grom mets, plastic tubing, adapters, and proper taping.

Inspect leading edge of wing for damage.

Inspect wing tips for dama ge and / or security o£ attachment.

The lens in the figure has been damaged by solvent and/ or cleaning agents and age.

Damaged or weakened lenses must be replaced since their failure can lead to severe wing damage. Inspect retractible landing lights for proper extension, retraction , and general con­ dition. FrcuRE 5-10. Electrical wiring, proper routing.

Ftcmu: 5-11. Satisfactory leading edge of wing.

### Page 65

!,~f ~:r: ;i:tf{'/[.:tnt!tir·m:!j;iifi:·: :·:

-·~ .•4 ,· :~;·

- l'W-.......-, :.··.

F'JGvu 5-12. Dented leading edge of wing.

### Page 66

F'JcURE 5-13. Damaged landing light lens.

F'JctJRB 5-14. Dtricer boot damage.

Inspect deicing boots for proper inflation and deflation. Check for punctures, bruises, loose patche s, and security of attachment. Examine deices pressure lines and fittings for leakage, security , and general condition.

Rubber hose connections from boots to tub­ FlGVBE 5-15. Block ·type gust lock.

ing must clear the holes through the structure , satisfactory installati on. Examine for cor­ and must be secured to prevent distortion of rosion and other defects.

the external surfa ce of the boot. Inspect control gust locks for condition. En­ If thermal anti-icing (hot wings) is utilized, sure that they release complet ely and cannot inspect the ducts for leakage, attachm ent, and possibly engage inad vertently.

### Page 67

Section 6. EMPENNAGE Inspect . fixed surfaces for damage or defects, Examine condition of ribs and stab ilizer spars loose rivets, scre,v c; or bolts, condition of cover­ at points of attachment for cracks and elon­ ing: cracked fittings , failure of glued joints, gated bolt holes. Inspect. prot ective coating and condition of drain grommets or holes. fo r deterioration.

FlcURE 6-1. Inspection chart-empennage.

### Page 68

Examine hydraulic lines for cracks, kinks, dents, or leaks, and inspect for security of attachment and wear due to chafing. Ensure that hydraulic actuators are securely mounted and free from leaks.

Inspect deicer boots for proper inflation and deflation, punctures, bruises, loose patches, and security of attachment. Check feedlines and fittings for leakage, security, and general con­ dition. If thermal anti-icing is used, inspect the ducts for corrosion, leakage, attachment, satisfactory installation, and other defects.

At all times during inspection, be alert for evidence of rust, corrosion, cracked or broken welds, loose rivets or bolts.

Inspect gust locks for condition. Ensure that they release completely and cannot pos­ sibly engage inadvertently.

Distortion of fabric or skin may indicate internal structural damage in the general area of the distortion.

Examine fabric or skin for abrasion, tears, cuts or other defects, distortion and deteriora­ tion. Check condition of protective finish and drain grommets. Ensure that the fabric or skin attachment to the structure is satisfactory.

Inspect external bracing attachment fittings for distortion, cracks, and security of attach­ ment. Check struts or brace wires for condi­ tion and security of attachment. Examine clevises for cracks, warn or damaged threads, and any other defects. Bracing should not be slack since this can cause flutter. Exces­ sive tension might distort or damage fittings and attachments. If there is any question con­ cerning condition of the external bracing, con­ sult a qualified mechanic.

~Lovable control surfaces such as elevators, rudders and trim tabs, should be examined for damage or defects, loose rivets, loose fabric, or skin distortion, and unsatisfactory glue joints. Inspect hinges and horns for security of attachment, breaks, bends, chafing, loose or worn pins, proper lubrication, and sa£etying.

Inspect control cables and bolts for wear at horns or bellcranks. Look for such things as FiGURE 6-2. Oilcanning of metal skin.

### Page 69

FIGURE 6-3. E11temal bracing checkpoints.

FiGURE 6-4. Rudder checkpoints.

frayed or chafed cables, pulle ys not turning, and displac ed cable guides. Inspect control system tubing for rust, corrosion, chafing, broken welds, or fittings. Inspect trim adj ust­ ment mechanism for excessive looseness, secu­ rity of attachment, and proper operation of the trim adjustment positio n indicator .

.If excessive clearance is detected in the hinges, a qualified mechanic should detenni ne corrective action needed.

If the aircraft is trimm ed by either an adju stabl e stab ilizer or trim tab, it must op­ erate freely thro ughout the designed range of travel. Lubri cate as required, followi ng the manufactu rer's recommendations.

Inspect navigation lights for condition and operatio n. Check wiring for chafing, proper insta llation, al):'d security of attac hment. Check installa tion:::; of grommet s, plastic tubing , adapte rs, arid oroper taping .

### Page 70

... , .

~-,-il\t~ i: b_~•­t ......

~~\lf!J\,-~_,:,~"1;\r,~-- .

·::tt~:{ ~~r ::- -- ..-:-... - ., .

. ,.,.......·

•.• • •-" w1 • . . ·, F'lc1nu! 6-5. Rudder quadrant.

### Page 71

FIGURE 6-6. Stabilizer adjuster checkpoints.

F1cvu 6-7. Position light checkpoints.

### Page 72

Section 7.

F1cuu 7-1. Inspection cbart-propener.

PROPELLER If unsati sfactory conditions are found while inspecting the propeller, a qualified mechanic should be consulted to determine the corrective action necessary. All propeller repairs must be accomplished by either the manufacturer or a propeller repair station except some minor repairs which may be done by a certificated mechanic. Hubs should be lubricated as recom­ mended by the manufacturer , using specified lubricants. Care should be used and the man­ ufacturer~s instruction s followed exactly when lubricating propellers to prevent introduction of imbalance. Such imbalance, even though hardly perceptible from the cockpit, can cause extensive damage to the propeller, engine, and airframe through resulting vibration.

A propeller should never be used as a hand­ hold for moving an aircraft. The thrust loads imposed on a propell er are much lighter than normally expected and are imposed while the propeller is rotating and subjected to centrif­ ugal loads. The propeller components are designed for the combination of these loads, and using the propeller for a handhold may severely damag e it, even though the damage may not be apparent.

Inspect the hub for corrosion, cracks, oil leaks, security o£ attachment, and safety. En- FIGUliE 7-2. Damaged metal blade.

### Page 73

sure that propeller retainer bolts are tight and properly safet ied.

Inspect metal blades for corro sion, cracks, nicks, and scrakhes, particularly on the lead­ ing edge of each blade from the tip inboard.

Even very small nicks and scratches set up stress concent rations which can lead to s truc- A. Dome .

B. Hub bolts.

c. Hub.

D. Blade.

tural failu res, especially in the propeller blades .

Propellers should be inspected at preflight and postflig ht. T his permits repair s to be made to scratches and nicks before further operation and with less likelihood of delaying a trip.

Remember, the longer a scratch or nick exists the greater the probability of failure.

E. Counterweight.

F. Deicer boot

c. Deicer boot leads.

H. Spinner bulkh ead.

FtcVRE 7-3. Three" blade propeller checkpoint s.

### Page 74

FlcURE 7-4. Propeller tip damage.

FIGURE 7-5. Wood propeller blade-craclced and separated lamina~ions.

This is an example of a propeller blade tip Wood or composition blades should be in­ which has been damag ed by lightn ing. Dama ge spected for condition o£ metal tipping and such as this should alert pilots and mechani cs leadin g edge strips. Check for loose rivets or to the probability of internal damage due to screws, separation of soldered joints, and other internal arcing. signs of creepin g or looseness of the metal 68

### Page 75

tipping. Check for lamination separation ~ espe­ cially between the metal l eadi ng e dge and cap.

Ensure that tip d rain holes are open so that the cent rifugal force of the revolving propeller will dissipate excess moisture. If other than a fixed-pitch propeller, make certain that the blades are installed in the hub sati sfactorily and properly safetied. \Vood blades installed into metal hubs should be frequently examined for cracks extending outward on the blade.

FWVRE 7-6. Propeller governor checlcpoints.

Inspect the propeller contro l system for security of attachment, oil leaks , freedom of movement and full travel. Insp ect wiring for condition, routing, damage, and chafing. In­ spect tubing for security , kinks , scratches, oil leaks, and chafing. Ensure that all exposed nut s are properly torqu ed and safetied.

The control system may incorporate a full feathering system including relays, solenoids , governors, or control valves, and distributor s.

Inspect the various external components of F'IGUIIE 7-7. Propeller spinner checkpoints.

the system for security of attachment, oil leaks, chafing, or damage to the electrical wiring.

Check for loose connections and proper safety­ mg.

Certain engine-propeller combinations re­ quire installa tion of a spinner for proper engine cooling. In these cases, the engine should not be operated unless the s pinner is properly installed .

Inspect the propeller spin ner and spinner mounting plate for security of attachment, cracks, chafing of the blades, proper safetying, and any other defects.

Cracked spinner assemblies should be re­ paired or repla ced immediatel y by a certificated person to prevent the possibility of parts break­ ing away in flight and damaging portions of the aircraft structure, or injuring personnel during operation on the ground.

Inspect the fluid anti-icer assembly for gen­ eral condition and security . Ensure that the slinger rings, nuts, and delivery tubes are prop­ erly installed and that the nuts holding the delivE"ry tubes to the slinger ring sockets are securely fastened. Inspect reservoir and lines for proper installation , chafing, or leakage.

Check connections for condition and security of clamps. Check fluid level and follow manu­ 69

### Page 76

FIGURE 7-8. Propeller liquid anti-icing system checkpoints.

facturer's instructions when filling reservoir with anti-icing fluid.

If the system depends on electrical heat for the removal of ice, inspect the deicing shoe for damage and condition of the electrical con­ nection to the blade. Examine blade slip rings and brush holders for condition and attach­ ment. Check cockpit controls for condition and satisfactory operation. Inspect wiring for chafing, routing, deterioration, and security.

Defects noted in the deicing system should be referred to a certificated mechanic for ad­ justments and repairs. Severe damage to the deicing shoe will require replacement. Nor­ mally, small cuts may be repaired with a sealer specified by the manufacturer.

FIGURE 7-9. Propeller electrical deicing system checkpoints.

### Page 77

Section 8. RADIO FIGURE 8-1. Inspection chart-radio.

Radio equipment should be removed pe­ riodically by certi ficated per sonnel to inspect shock moun ts and bound ing, and to clean and inspect racks and adja cent structure . Plugs and connectors should be opened and inspected for corrosion , dirt, and moisture. Ensure that all plugs and connectors are properly mated and secured.

Disconnect battery ground cable BEFORE removing radio equipment. Check for broken bonding strips. Poor radio reception will gen­ erally result from broken bonding strip s.

Examine installation of communi cation and navigation equipment (transceivers, ADF, OMNI, DME , etc.) for security of attachment. FIGURE 8-2. Communication/navigation equipment Check all jacks, knobs, and switches for se­ installation checkpoints.

### Page 78

curity. Volume controls should work smoothly.

Switches should have positive action. Indi­ cator dials should be clean and have proper motion. Check for defective light bulbs. Spare light bulbs and fuses should be readily avail­ able in the cockpit or cabin.

FIGuRE ~- Bonding radio equipment to shock mount.

Inspect electrical wiring and shielding for defects, chafing, aqd security . Ensure that connections, terminals, and clips are tight.

Look. for evidence of shock mounted equip­ ment contacting adjacent components or struc­ ture. Inspect iuses for corrosion, continuity, and security.

FIGURE 8-4. Communication/navigation equipment shock mount.

Inspect dynamotors for security of attach­ ment and cleanliness. Inspect power supply installation for security of attachment. Check wiring and connections for proper grounding, condition, insu]ation, and security. Check switches for operation and condition.

Periodically, check the voltage regulator sys­ tem. Low voltage settings will result in im­ proper radio operation. High voltage setting (over 10 percent) may result in damage to radios, particularly those incorporating tran­ sistors.

FIGURE 8-5. Typkal communication/navigation equipment control.

An operational check should be performed on all equipment during engine warmup . Re­ ception should be free of interference caused by ignition, generators, navigation lights, or any other electrical or mechanical unit.

Headsets and microphones should be in­ spected for broken or sticking switches, and dirty, worn, or damaged plugs. Inspect cord for wear and damage.

Unsatisfactory operation of communication or navigation equipment should be referred to authorized personnel for repair or adjustment.

Open junction boxes and inspect for extra­ neous material, security of connections, and condition of wiring and cables. Inspect remote control shafts for condition, security, and ease of operation.

The emergency locator transmitter (ELT) should be inspected for general condition , se­ curity of attachment, and other defects. The antenna cable and remote switch cable should be securely attached with no corrosion of com­ 72

### Page 79

FtcVRE 8-6. Antenna installations checkpoints.

ponents and routed so as not to interfer e with controls. Be sure that the battery repla cement date has not expired. Look for leakage and corrosion of the battery pack or ELT unit if batteries are utilized internally. Inspect the ELT antenna for security, corrosion, or damage. Inspect the cockpit ELT remote function switch for security and proper posi­ tion. Note: Operational tests may be con­ ducted only at certain times. Generally, . operational tests will be perfopned by repair agencies following maintenance or repair of ELT.

FrouRE 8-7. ADF Antenna-internal loop-tail mount .

Check anten nas for condition and security of attac hment. Inspect wire antennas for proper tension. Inspect insulators, fittin gs, terminals, and supporting masts for condition and securi ty. Clean all insulators.

A broken ant enna may foul the cJntrol s or cause other damage . Inspe ct ~gid antennas and masts for ev,idence of lightning strikes.

Check rubber seals for evidence of cracks or leakage.

Check manu al and automatic rotation of automatic direct ion finder (ADF) loop.

Ftcmu: 8-8. ADF antenna-fixed Joop.

Refinishing an ADF loop housing requires a special paint .

Inspect trailing edge static wicks for proper length, condition, and security.

### Page 80

F'lc:mll; 8-9. Bonding wires and trailing edge static wicks.

### Page 81

Section 9. MISCELLANEOUS Miscellaneous equipment should be inspected for general condition, proper storage, and to ensure that it is readily accessible. Ensure that all equipme nt is secured so that it cannot interfere with the controls.

Para chutes, lift rafts, flares, and similar emergency equipment should be inspected by qualified , personnel within prescribed time pe­ riods according to manufa cturer' s recommen­ dation s. All noted defects or discrepancies should be referred to an approved repair facilit y.

F'JGURE 9-2. Autopilot control panel.

FiGtJBE 9-1. Rotating beacon installatian.

Inspe ct rota ting or flashing beacons for se­ curity of mounting, cleanlines s, and general condition. Inspect wiring for condition and possible chafing. Check switches for proper operation. Examine connections for tightness , corrosion, and condition of insulation. Ensure that fuses or circuit breakers are in good con­ dition and operating satisfactorily.

Insp ect the autopilot system for general con­ dition, secur ity of attachment , and for other defects. Functional checks should be per­ formed in accordance with the manufacturer's instru ctions. 9-3. Emergency locator transmitter - remote mount.

### Page 82

Check ELT mounting and connections for security. Check batteries for expiration/re­ placement date . Any evidence of corrosion should be investigated by qualified personnel.

Perform an operational check periodically.

Fire extinguishers should be checked for indication of being discharged, proper quantity of extinguishant, and location-away from any area of excessive heat or direct sunlight.

The first aid kit should be checked to deter­ mine the condition and sufficiency of its con­ tent.

9-4. Emergency locator . transmitter - portable mount .

### Page 83

3 4!:'.'77 "" Section 10. PREFLIGHT INSPECTION 4 2 FICUIIE 10-1. Inspection chart-preflight .

### Page 84

The following Preflight Inspection Check­ list may be used as a guide when developing a preflight checklist for your aircraft. It should be modified to suit the aircraft type and to include the manufacturer's recommenda­ tions (normally found i:: the Pilots / Owners Operation Handbook).

The numbers on the inspecti on chart cor­ respond to the numbers indicated on the item­ ized list. By following the numerical route, an effective and organized preflight inspection can be accomplished.

1. The first three items to be accomplished are:

Battery and igniti on switches-OFF Control locks-REMOVED Landing gear control-GEAR DOWN

AND LOCKED After completion of item Number 1, proceed with the preflight inspection.

Carefully observe the general overall ap­ pearance of the airp lane.

2. Fuselage : Right side Exterior of cockpit doors/ passenger · door~heck for security of hinges and latch lock. Check condition of skin and windows.

Baggage compartment~ontents secured and door locked.

Airspeed static source- free from ob­ structions.

Condition of covering- missing or loose rivets, cracks, tears in fabric, etc.

3. Empennage:

Deicer boot~ondition and security.

Control surface locks--"REMOVE."

Fixed and movable control surfa cesdents , cracks, excess play, hinge pins and bolts for security and movable sur­ faces for full trave l and freedom of movement.

Tailwheel--spring, steering anns and ch.ains, tire inflation, and condition.

Lights-navigation and anticollision lights for condition and security.

4. Fuselage : Left side Same as item 2.

5. Wing:

Control surface locks-"REMOVE."

Control surfaces, including flaps'---dents, cracks, excess play , hinge pins and bolts for security and condition, mov­ able surfaces for full travel and free­ dom of movement.

General condition of wings and cover­ htg-torn fabric, bulges or wrinkles , loose or missing rivets, "oil cans," etc.

6. Wing tip and navigation light~ondi­ tion and security.

7. Deicer boots-ge neral conditio n and se­ curity.

Landin g ligh~ondition, cleanliness, and security .

Stall warning vane-freedom of move­ ment. Prior to inspection, turn master switch "ON" so tba~ stall warning signal can be checked when vane is deflected.

8. Landing gear:

Wheels and brake~ondition and se­ curity, indications of fluid leakage at fitting s, fluid lines, and adjacent area.

Tires-cuts, bruises, excessive wear, and proper inflation.

Oleos and shock struts~leanliness and proper inflation.

Shock cords-gen eral condition .

Wheel Fairings-general conditi on and security. On streamlined wheel fair­ ings, look inside for accumulatio n of mud, ice, etc.

Limit and position switcht'!S- security:

cleanliness, and condition.

Ground safety locks--"REMOVE."

### Page 85

Fuel quantity in tank:

Fuel tank filler cap and fairing covt'<t'S­ secure.

Fuel tank vents-obstructions.

When fuel tank is equipped with a quick or snap-type drain valve, drain a suf­ ficient amount of fuel into a conta iner to check for the presence of water and sediment.

10. Engine:

Engine oil quantity-secure filler cap.

General condition and evidence of fuel and oil leaks.

Cowling , access doors , and cowl flaps­ condition and security.

Air inlet screen-cleanliness and security.

··· Drain a sufficient · quantity of fuel from the main fuel sump drain to determine that there is no water or sediment re­ maining in the system.

11. Nose landing gear:

Wheel and tire---euts~ bruises, excessivP.

wear, and proper inflation.

Oleo and shock strut-proper inflation and cleanliness. .

Wheel well arid fairing-general condi­ tion and security.

Limit and position switches-cleanliness, condition , and security.

Ground safety lock-"REMOVE."

12. Propeller : .· Propeller and spinner-security , oil leakage, and condition.

Be particularly observant for nicks and scratches. If the engine runup will be accomplished at this location, ensure that ground area under propeller lS free of loose stones, cinders, etc.

13. Fuel tank:

Sanie as item 9.

14. Landing gear:

Same as item 8.

15. Pitot :

Pitot cover- " REMOVE ."

Pitot and stat ic ports~free of obstruc­ tions.

General condition and alignment.

Deicer boots and landing edge of wing.

16. Same as item 6 (Wing tip and navigation light-condition and security).

17. Same as item 5 (Wing).

18. Cockpit:

Interior of cockpit door / passenger doors -check for security of hingeS and latch or lock. Check for condition of door lining s.

Cleanlines s and loose articles.

Windshield and windows-obvious de­ fects and cleanliness.

Safety belt and shoulder harness-<lon­ dition and security.

Check security and adjustment of pilot's seat.

Pilot's seat-locked.

Adjust rudder pedal s to ensure full rud­ der travel.

Check all flight control surface and trim tabs for full tra vel, right or left , up or down.

Trim tabs- "SET."

Parking brake-"SET."

Landing gear and flap switches or levers in proper position.

Check all switches and controls.

Cabin atmosphere control system.

Oxygen system.

Communication system.

Emergency locator beacon.

With a fireguard' available, start the engine / engines and proceed with en­ gine run-up following the engine man­ ufacturer's recommendations.

### Page 86

Section 11.

After storage, an aircraft should have a thor­ ough inspection. It is especially recommended for aircraft that have be€n tied down outside, or stored for an extended period of time. Air­ craft are frequently used for nesting by insects, birds, and animals. Bird nests in air intake scoops will impair airflow, result in excessively rich mixtures, and may even cause engine stop­ page. Xests lodged between engine cylinders and engine baffles can cause overheating, pre­ ignition, detonation, and fires.

Bird nests may also be found inside wings, control surfaces, and fuselage, if there is an entrance available. ·wheel wells of retractable landing gear aircraft are a :favorite nesting area.

FIGURE ll-1. Birds nest.

Insect nests can obstruct fuel tank vents and cause lean mixtures and fuel starvation. Mice will cut rib stitching and make the wings un­ safe. Excretions from rodents are highly cor­ rosive to aluminum alloy metals and are harmful to fabric and wood. Deterioration or excessive weather-checking of fuel, oil, hy­ draulic, or induction hoses may result in leaks and faulty operation. In view of these facts, it is mandatory that the following be checked:

Oil coolers and intake scoops.

Carburetors, intake screens, and passages.

AFTER STORAGE Fuel tank vents.

Pitot tubes.

Fuselage interior and baggage areas.

Interior of wings and control surfaces.

Static vents.

Exposed drain tubes.

Open wheel wells.

Engine cylinders and baffles.

Fluid lines and hoses.

Winter Operation When fuel caps are flush with the wing upper surface, they may collect water in the filler overflow well. This water may freeze during cold weather operations, resulting in blockage of the fuel tank vent and engine op­ eration. Partial obstruction of the vent may cause erratic engine operation and loss of power. In aircraft using engine-driven fuel pumps, the tank may collapse causing struc­ tural damage.

Check carburetor air scoop for obstructions and open the drain if so equipped. Reclose.

Check carburetor air filter screens for obstruc­ tions to airflow from ice and snow accumula­ tion.

Drain fuel tank sum!J"' regularly. W at.er can form in the fuel tank and this can result in restricted fuel flow, cracked lines, and cracked fuel strainer bowls.

Blowing snow may seep into the :fuselage, wings, and control surfaces, where it will melt and may accumulate in a low point and freeze.

The weight of this ice may be great enough to seriously affect safe flight. Make sure that al] frost, snow, and ice are removed from the air­ craft, especially from the top of wings and other airfoil surfaces.

Check for proper operation of oil cooler shutters or use of covers as specified by the aircraft manufacturer. Determine that the oil used is recommended by the engine manufac­ turer.

### Page 87

**APPENDIX A**

GENERAL SAFETY PRECAUTIONS Good housekeeping in hangars, shops, and on the flight line is essential to safety and efficient maintenance. The highest standards of orderly work arrangements and cleanliness should be observed while maintaining an air­ craft. "'\Vhen the maintenance inspection task is complete, remove and properly store main­ tenance stands, hoses, electrical cords, hoists, crates, boxes and anything else used to perform the work.

Pedestrian lanes or fire lanes should be marked and utilized as a sa1ety measure to prevent accidents and keep pedestrian traffic out of work areas.

Power cords and air hoses should be straight­ ened, coiled, a:1d properly stored when not in use.

To prevent aircraft damage or personal in­ jury, the use of wheel or wing jacks on uneven or soft ground, or under windy conditions, should be avoided. Jack or raise the aircraft only in a closed hangar having a firm level floor.

Application of aircraft finishes (dope or lacquer) should be accomplished in a controlled environment (paint room) whenever possible.

Never do this type work in the presence of lights that are not explosion proof or an open flame. Do not permit other work on an air­ craft when it is being painted. Keep fire lanes clear and fire extinguishers available. Locate aircraft not being painted so as to permit quick removal from the shop or hangar.

Oil, grease, or any slippery substances spilled on hangar or shop floors should be immediately removed. If spills cannot be removed, they should be covered with an absorbent material to prevent fire or personal injury. Drip pans should be placed beneath engines and engine parts whenever dripping exists.

To prevent possible personal injury, appro­ priate safety devices should be used in mount­ ing or removing aircraft tires. ·when inflating tires on the wheels, tire gauges should always be used. Extreme caution and the use of pres­ sure regulators is required to a void overinfla­ tion of high-pressure tires. Never use high pressure air bottles to inflate tires.

Welding on aircraft in the hangar should never be permitted except in carefully con­ trolled areas. vVhen welding is required, get a professional to perform the work in con­ formance with the manufacturer's approved procedure.

Servicing Aircraft Oxygen Systems Oxygen is a chemically stable, nonflammable gas, however, combustible materials ignite more rapidly, and burn with greater intensity in an oxygen-rich atmosphere. When oxygen com­ bines with oil, grease, or any other petroleum product, it forms a highly explosive mixtur~.

Petroleum products are extremely sensitive to impact and spontaneous combustion when ex­ posed to oxygen.

Before servicing any aircraft, consult the specific aircraft maintenance manual to deter­ mine the proper type of servicing equipment to be used. Aircraft should not be serviced with oxygen during fueling or other mainte­ nance work. Oxygen servicing of aircraft should be done outside of hangars and by qualified personnel.

Aircraft Tiedown Aircraft not in use and parked outside should be tied down at all times. Prevailing wind and weather conditions will influence the amount of security needed in tying down air­ 81

### Page 88

craft. Under normal conditions minimum se­ curity is sufficient, but whenever winds or storms are forecast, additional tiedowns should be added.

Aircraft should be headed, as nearly as pos­ sible, into the prevailing wind, depending on the locations of the parking area's fixed tie­ down points. After the aircraft is properly located, center the nose wheel or the tailwheel in the fore-and-aft position. Aircraft which are not equipped with tiedown fittings should be secured in accordance with the manufac­ turer's instructions.

Tiedown Anchors All parking should provide at least three­ point tiedown (three anchors). Heavy aircraft may require five or more. Anchors installed in paved parking areas are adaptable to any size aircraft. When parking aircraft, spacing should provide :for wing tip clearance.

Control Locks Control locks (blocks) or gust locks should be installed anytime an aircraft is not in use.

General Precaution The security and prevention of damage to aircraft not in use depends upon the owner , pilot, or aircraft operator taking necessary precautions. The availability of weather con­ dition reports should provide ample time to take additional safety precautions regarding severe weather, 82

### Page 89

**APPENDIX B**

AVIATION FUEL-IDENTIFICATION AND FUELING PROCEDURES Gasoline The tetraethyl lead content of aviation :fuel determines the grade rating.

Maximum Tetraethy~ Lead Gra-de.jOctane Rating Color Per Galhm 80 Red 0.5 ml. gal.

lOOLL (Low Lead) Blue 2.0 ml. gal.

lOOHL (Hi Lead) Green 8.0 ml. gal.

The higher grade ratings are for use in high compression engines.

Always use the grade of fuel recommended by engine manufacturer (regular or alternate).

The availability of different fuel grades at servicing :facilities is largely dependent on the classes of aircraft using the facility. Most f~el service units plainly indicate the type and grade of fuel. Another check for proper grade fuel is to compare the fuel color with the col­ ored band on the service hose. A band 12" in width indicating fuel grade must be painted on the :fuel hose adjacent to the fitting used to dispense the fuel. Fuel grade is painted within this color band.

Jet Fuel There are three types of jet fuel in common use today:

1. Kerosene grade turbine fuel, now desig­ nated as Jet A;

2. A blend of gasoline and kerosene desig­ nated as Jet B;

3. A third type, called Jet A-1, for operation at extremely low temperatures.

Most commercial turbine engines will oper­ ate on either Jet A or Jet B fuel. However , the difference in the specific gravity of the fuels may require fuel control adjustments;

check the FAA-Approved Airplane or Rotor­ craft .Flight Manual or engine information for instructions.

Fueling Aircraft Do not fuel or defuel an aircraft in a hangar or other enclosed space. The aircraft should be free from fire hazards, and have the engine switches off. Chocks should be placed under the wheels prior to fueling or defueling. Fire extinguishing equipment should be available on the fuel service veh]cle or at the fuel hydrant.

Pressure fueling is used on many late-model aircraft. This is sometimes referred to as "single-point" or "underwing" fueling. It greatly reduces the time required to service large aircraft. Pressure fueling also reduces the chance of static electricity igniting fuel vapors. The design of pressure fueling sys­ tems varies with each type of aircraft.

Consult the manufacturer's instructions for detailed procedures on how each system func­ tions.

All fuel is filtered through water-separating equipment installed in the system between the supply tank and the service truck. In the case of island-type refueling stations, it is filtered as it leaves the supply pumps. These filters and separators are usually checked each day for evidence of dirt and water . This is also done each time a mobile refueler is reloaded.

Fuel which has been stored in cans or barrels should be run through a strainer- funnel be:fore being put into an aircraft . This practice is necessary because condensation and rust de­ velop inside cans and barrels. An increase in the hazard of static electricity results when the gasoline passes through filters. The filter 83

### Page 90

should be grounded and remain grounded until all gasoline has drained through it. Never use a plastic funnel, bucket , or similar nonconduc­ tive container when servicing from storage cans or barrels.

·when fueling aircraft by truck, the aircraft should be located on the apron or a dispersal site. The tank truck should be as far from the aircraft as the hose will permit, preferably· to the windward or upwind side. Identify the aviation fuel and lubricating oil dispensed from each fueling unit before beginning the actual servicing. The fueling technicians should be familiar with the various grades of gasoline so that only the appropriate fuel will be used.

There should be no lights other than ap­ proved explosion-proof lights permitted within 100 feet of the fueling operation. Exposed electric switches, sliprings or commutators, dynamos or motors, and spark-producing elec­ trical equipment, should not be operated within 100 feet of fueling operations.

All nonessential circuit switches should be "OFF.'' Assure that both the aircraft and the truck are properly grounded to prevent static electricity sparks. To accomplish this, a sepa­ rate ground wire should be connected from aircraft to ground, from fuel truck to ground, and the hose nozzle grounded to the aircraft.

If aircraft fuel or other combustible liquid is spilled, it should be immediately removed by washing with water. It may also be covered with a foam blanket or neutralized by other means. Tools of nonsparking metal should be used when working on any part of a system or unit which is designed for storing or handling gasolines. Notify the proper fire authorities if the situation so dictates.

Oil Aircraft oil tanks are normally checked at the same time the fuel tanks are filled. There are a few exceptions to this general rule. Some manufacturers recommend that the oil level in certain jet engines be checked within a speci · fied time after engine shutdown. In all cases, the manufacturer's instructions should be fol­ lowed not only for servicing procedures but also for type and grade of oil used.

### Page 91

**APPENDIX C**

CERTIFICATE OF REGISTRATION-AIRCRAFT ELIGIBILITY AND APPLICATION The purchaser of an aircraft must apply for a Certificate of Aircraft Registration before he flies it. The Aircraft Registration Applica ­ tion, AC Form 8050-1, consists of an original, two duplicate copies, and instructions for its preparation and submission.

An application for a registration certificate must be accompanied by an aircraft bill of sale or other evidence of ownership. A bill of sale which meets the recording requirements of the Federal Aviation Administration is AC Form 8050-2, Aircraft Bill of Sale.

The temporary copy of the application must be placed in the aircraft until the permanent certificate of registration is received from the Federal Aviation Admini stration.

Make sure the certificate of aircraft regis­ tration has not expired. If one of the follow­ ing exists, it is no longer valid :

1. The aircraft is registered under the laws of a foreign country;

2. The registration of the aircraft is canceled at the written request of the owner;

3. The aircraft is totally destroyed or scrapped; (If the aircraft is destroyed, the owner should notify the FA.A. by fil­ ing in the back of his Certificate of Air­ craft Registration, AC Form 8050-3, and mailing it to the F A.A. Aircraft Registry, P.O. Box 25082, Oklahoma City, Okla­ homa 73125.)

4. The ownership of the aircraft is trans­ ferred;

5. The holder of the certificate loses his United States citizenship; and

6. Thirty days have elapsed since the death of the holder of the certificate.

### Page 92

**APPENDIX D**

CERTIFICATE OF AIRWORTHINESS-GENERAL INFORMATION An Airworthiness Certificate is issued by a representative of the Federal Aviation Admin­ istration after the inspection has been com­ pleted, and the aircraft is found to meet the requirements of the Federal Aviation Regula­ tions (FARs), and is in a condition for safe operation. The certificate must be displayed in the aircraft so that it is legible to passengers or crew whenever the aircraft is operated. The Airworthiness Certificate is transferred with the aircraft when it is sold.

The Standard Airworthiness Certificate, FAA Form 8100-2, is issued for aircraft type certificated in the: (1) normal; (2) utility;

(3) acrobatic ; ( 4) glider; ( 5) manned free balloon; and (6) transport categories.

The Special Airworthiness Certificate, FAA Form 8130-7, is issued for all aircraft certifi­ cated in other than the standard classifications, such as experimental, restricted, limited, and provisional. If an aircraft is classed as other than standard, contact your local FAA General Aviation District Office for an explanation of the pertinent airworthiness requirements and the limitations of such a certificate.

In summary, the FAA initially determines that an aircraft is in safe operating condition, conforms to a type design, and then issues an airworthiness certificate. A Standard Air­ worthiness Certificate remains in effect so long as the aircraft receives the required mainte­ nance and is properly registered in the United States. Flight safety depends, in part, on the condition of the aircraft, which may be deter­ mined on inspection by cet:_iificated mechanics, approved repair stations, or manufacturers who meet specific requirements of. FAR Part

43.

---
From OpenAirDocs.org, an independent open copy of FAA and NTSB data. Only the Federal Register edition on govinfo.gov is the official legal text of an AD.