AC 20-106
AIRCRAFT INSPECTION FOR THE GENERAL
AVIATION AIRCRAFT OWNER APRIL 1978 U.S. DEPARTMENT OF TRANSPORTATION
FEDERAL AVIATION ADMINISTRATION Flight Standards Service For sale by the Superintendent of Documents, U.S. Government Printing Office Washington, D.C. 20402
PREFACE The inspections described in this Aircraft Inspection handbook are NOT intended to replace any required inspection. Rather, they are intended to familiarize persons with the techniques generally applicable to aircraft inspections whether they be owners. pilots, student mechanics, or others with aviation interests.
The services of an appropriately rated certificated repair station, certificated mechanic, or the manufacturer must be utilized for all required inspections and whenever any inspection reveals a questionable condition. We emphasize the fact that reliable inspection capability comes only with experience, and the use of this handbook does NOT qualify an individual to make final airworthiness determinations.
PART I-INSPECTION FUNDAMENTALS Inspection requirements, owner's responsibilities, inspection time intervals, and sources of basic information are discussed in Part I.
PART II-INSPECTION TECHNIQUES The general techniques used to inspect an aircraft are discussed in Part To facilitate reference, in the explanation of important inspection processes, arrows appear on many of the illustrations. These indicate either the item or the general area to which the text refers.
Numerous illustrations are used to convey information to the reader in the most clear, graphic, and effective manner.
Acknowledgment of cooperation is extended to the following:
Beech Aircraft Corporation Cessna Aircraft Company Cessna Aircraft Company Aircraft Radio and Control 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. Suggestions for revision and improvement of this handbook are encouraged and may be forwarded to Department of Transportation, Federal Aviation Administration, Flight Standards National Field Office, AFS-500, P.O. Box 25082, Oklahoma City, Oklahoma 73125.
AIRCRAFT INSPECTION FOR THE GENERAL
AVIATION AIRCRAFT OWNER Contents Page Preface ------------------- i Part I. Inspection Fundamentals Section 1. The Inspection Process Section 2. Preventive Maintenance Section 3. The Forces of Attrition 7 Section 4. Inspection Do's and Don'ts 14 Part II. Inspection Techniques 15 Section 1. Fuselage ---- 15 Section 2. Cabin-Cockpit 21 Section 3. Engine Nacelle 27 Section 4. Landing Gear 42 Section 5. Wing-Center Section 53 Section 6. Empennage - 61 Section 7. Propeller --- 66 Section 8. Radio 71 Section 9. Miscellaneous 75 Section 10. Preffight Inspection 77 Section 11. After Storage 80 APPENDIX A. General Safety Precautions 81 APPENDIX B. Aviation Fuel-Identification and Fueling Procedures ---- 83 APPENDIX C. Certificate of Registration-Aircraft Eligibility and Application - 85 APPENDIX D. Certificate of Airworthiness-General Information 87 List of Illustrations PART I. Inspection Fundamentals Figure Page I-1. Five stresses acting on aircraft - 10 Part II. Inspection Techniques Section 1.
1-1. Inspection chart-fuselage 1
1-2. Cracked fuselage structure 16
1-3. Cracked former ------
1-4. Distorted fuselage skin 16
1-5. Deteriorated fuselage fabric 16 ili
Figure Page
1-6. External wing bracing attachment checkpoints - 16
1-7. Proper cable routing ---
1-8. Improper cable routing -.
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 fuselage (light twin) 20 Section 2.
2-1. Inspection chart-cockpit .
2-2. Inspection chart-cabin -..
2-3. Operational check-fuel tank selector valve -
2-4. Circuit breaker and fuse panel
2-5. Check quantity hydraulic fluid
2-6. Instrument panel -
2-7. Bellcrank checkpoints ---
2-8. Cable rubbing bulkhead
2-9. Gustlock -
2-10. Frayed safety belt
2-11. Safety harness -
2-12. Inspection items on seat Section 3.
3-1. Inspection chart-engine and nacelle
3-2. Inspection chart-engine
3-3. Fuel strainer checkpoints
3-4. Carburetor inspection points
3-5. Carburetor air filters ---- 30
3-6. Intake manifold checkpoints
3-7. Oil tank inspection -.
3-8. Oil quantity check -
3-9. Satisfactory oil line installation
3-10. Unsatisfactory oil line installation
3-11. Oil-cooler checkpoints ---
3-12. Checking sparkplug torque
3-13. Unsatisfactory sparkplug cigarette
3-14. Igniter plug-gas turbine engine
3-15. Exhaust manifold checkpoints
3-16. Exhaust stack damage --
3-17. Heat exchanger-shroud removed
3-18. Cowl flap checkpoints ---
3-19. Engine baffles -
3-20. Engine mount checkpoints
3-21. Cracked engine mount ---
3-22. Checking starter security -
3-23. Inspect cowling for damage
3-24. Damaged cowling - iv
Figure Page
3-25. Repaired cowling ----
3-26. Cowling installation checkpoints
3-27. Evidence of chafing --
3-28. Battery installation checkpoints Section 4.
4-1. Examples of tire defects
4-2. Tire protected by drip pan
1-3. Multiple disc-type brake'
4-1. Shoe and drum-type brake
4-5. Expander block-type brake
4-6. Disc brake inspection points -
4-7. Wheel and brake inspection points
4-8. Hydraulic brake line checkpoints -.
4-9. Simple master cylinder brake systems -
4-10. Cockpit-hydraulic brake line checkpoints
4-11. Wheel checkpoints ---
4-12. Inspection chart-fixed landing gear
4-13. Fixed nose gear checkpoints --
4-14. Oleo-type landing gear checkpoints
4-15. Steerable tailwheel inspection points
4-16. Inspection chart-retractable landing gear
4-17. Retractable main gear checkpoints
4-18. Landing gear retracting --
4-19. Retractable nose gear checkpoints
4-20. Retracting mechanism checkpoints
4-21. Typical electrical retraction installation
4-22. Electrical retracting motor and wiring
4-23. Warning microswitch installation
4-21. Gear attachment structure checkpoints
4-25. Float installation inspection points
4-26. Ski installation inspection points - 52 Section 5.
5-1. Inspection chart-wing-center section
5-2. Indication of defective fabric
5-3. Wood structure inspection points - 54
5-4. Metal structure inspection points - 55
5-5. Lighting damage-flap, lower surface 56
5-0. Control bellerank checkpoints 5ă
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
Figure 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 checkpoints ----- 63
6-5. Rudder quadrant ------. 64
6-6. Stabilizer adjuster checkpoints 65
6-7. Position hight checkpoints 65 Section 7.
7-1. Inspection chart-propeller 66
7-2. Damaged metal blade --- 66
7-3. Three-blade propeller checkpoints - 67
7-4. Propeller tip damage __------- 68
7-5. Wood propeller blade-cracked and separated lamination 68
7-6. Propeller governor checkpoints 69
7-7. Propeller spinner checkpoints - 69
7-8. Propeller liquid anti-icing system checkpoints - 70
7-9. Propeller electrical deicing system checkpoints 70 Section 8.
8-1. Inspection chart-radio 71
8-2. Communication/ navigation equipment installation checkpoints - 71
8-3. Bonding radio equipment to shock mount - 72
8-4. Communication/navigation equipment shock mount - 72
8-5. Typical communication/navigation equipment control 72
8-6. Antenna installations checkpoints 73
8-7. ADF antenna---internal loop-tail mount 73
8-8. ADF antenna-fixed loop 73
8-9. Bonding 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-preflight 77 Section 11.
11-1. Bird's nest ------------ 80 vi
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, structural strength, and resistance to vibration.
Inspection interval requirements are established 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 inspected 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 airplanes may be inspected in accordance with a progressive 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, Sections 91.169, 91.171, or Subpart D of FAR 91. The latter prescribes an inspection program for large and turbine-powered multiengine airplanes (turbojet and turboprop). If you are concerned with the inspection of a large airplane (over 12,500 pounds) or a turbojet or turbopropeller-powered multiengine airplane, 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 inspection techniques will be similar.
FAR 91-General Operating and Flight Rules.
Subpart C of Part 91 prescribes rules governing the maintenance, preventive maintenance, and alteration of 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 governing the maintenance, preventive maintenance, rebuilding, and alteration of aircratt as well as standards for their performance.
Inspection.
Inspection is the critical visual examining, testing, measuring, and functional checking required to determine the airworthiness of the items being inspected.
NOTE: As mentioned in the preface, the services of a certificated repair station, certificated mechanic, or the manufacturer must be utilized for all required inspections and whenever any inspection reveals a questionable condition.
Scope of Inspections.
Aircraft inspection may range from a casual "walk-around" to a detailed inspection involving complete disassembly and the use of complex inspection aids. The inspections described 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.
The inspection of your aircraft should become a habit. To establish the habit, begin by performing preflight inspections and work up to detailed inspections. USE the MANUFAC- TURER'S RECOMMENDATIONS and this handbook as a guide. Develop a system of 1 319-470 0 - 80 - 2
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 inspection of aircraft at specific intervals and that they be approved for return to service by certificated and appropriately rated personnel.
The purpose of this handbook is to familiarize interested persons with general inspection techniques and to assist pilots and owners in establishing 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 inspect 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 establishing these intervals.
Historically, inspection intervals have been established on the basis of flying hours. However, 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 hours Fuselage interior-every 100 hours, etc.
By calendar weeks (eight-week cycle) :
Daily preffight inspection (including propeller and engine controls) Powerplant-first and fifth weekend Flight control system-second and sixth weekend Landing gear-third and seventh weekend Cabin or cockpit--fourth and eighth weekend 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. Regardless 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 periods of inactivity, and type of storage facili- 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 necessary 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 supplemental in nature, you should specify exactly what inspection is to be accomplished and require the person conducting the inspection to furnish a written statement of the results.
Aircraft Logs.
"Logs," as commonly used, is an inclusive term which applies to the aircraft record "books," and to all supplemental records concerning the aircraft. These logs and records provide a history of maintenance and operation, a control for inspection schedules, data needed to properly accomplish time replacements 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.
Section 2. PREVENTIVE MAINTENANCE Preventive maintenance means simple preservation and the replacement of small standard parts not involving complex assemblies. It is corrective action taken before it becomes necessary to make more complex repairs.
following preventive maintenance may be accomplished by a certificated pilot, who is the owner or operator of an aircraft, not used in air carrier service.
This list comes from FAR 43, Appendix A, Major Alterations, Major Repairs, and Preventive Maintenance, paragraph (c). It reads as follows:
i (c) Preventive maintenance. Work 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 requiring rib stitching or the removal of structural parts or control surtaces.
(8) Replenishing hydraulic fluid in the hydraulic reservoir.
(9) Refinishing decorative coating of fuselage, wings, tail group surfaces (excluding balanced control surfaces), fairings, cowling, landing gear, cabin, or cockpit interior when removal or disassembly of any primary structure or operating system is not required.
(10) Applying preservative or protective material to components where no disassembly 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 interior when the repairing does not require disassembly of any primary structure or operating system or interfere with an operating system or affect primary structure of the aircraft.
(12) Making small simple repairs to fairings, nonstructural cover plates, cowlings, and small patches and reinforcements not changing the contour so as to interfere with proper airflow.
(13) Replacing side windows where that work does not interfere with the structure or any operating system such as controls, electrical equipment, etc.
(14) Replacing safety belts.
(15) Replacing seats or seat parts with replacement parts approved for the aircraft, 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-
(19) Replacing any cowling not requiring removal of the propeller or disconnection of flight controls.
(20) Replacing or cleaning spark plugs and setting of spark plug gap clearance.
(21) Replacing any hose connection except hydraulic connections.
(22) Replacing prefabricated fuel lines.
(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 installation and when such removal and installation can be accomplished by the pilot."
Technical data for use in performing preventive maintenance may be found in the manufacturers' manuals. General data on aircraft maintenance may be obtained from the following Advisory Circulars (AC) published by the FAA. All are available from the Superintendent of Documents (Supt. Docs.) and should be ordered by the stock numbers (SN) listed after each AC.
AC 65-9A, Airframe and Powerplant Mechanies General Handbook, is designed as a study manual for persons preparing for a mechanic certificate with airframe or powerplant ratings.
Emphasis in this volume is on theory and methods of application. It is intended to provide basic information about principles and fundamentals common to both the airframe and powerplant ratings. (S.V 050-007-00379-
o.)
AC 65-12A, Airframe and Powerplant Mechanics Powerplant Handbook, is designed to familiarize student mechanics with the construction, theory of repair, operation, and maintenance of aircraft powerplants and propellers. (SN 050-007-00373-1.)
AC 65-15A, Airframe and Powerplant Mechanics Airframe Handbook, is designed to tamiliarize student mechanics with construction, theory of repair, operations, and maintenance of airframe and airframe systems.
050-007-00391-9.)
Advisory circulars are available either free from FAA or sold by the Superintendent of and current prices are listed in the FAA Advisory Circular Checklist, AC 00-2. The checklist should be consulted for current information before placing any orders. (A reference copy is available at any FAA office or GPO Bookstore.)
The checklist is published three times a year and is available free from Department of Transportation, Publications Section, M-143.1, Washington, D.C. 20590.
The Status of Federal Aviation Regulations, AC 00-41, is issued as changes require and is also available free from the above address.
Malfunction or Defect Reports (FAA Form 8330-2) are provided free of charge and with return postage paid by the FAA. They are normally preaddressed when provided, and are a convenient means of ensuring that data, required to make the report meaningful, is included.
These reports are a means by which the aviation community may interchange service information since the data received on the reports is published in numerous FAA publications, available free or on a subscription basis.
Malfunction or Defect Reports are also a data source used by the FAA in monitoring the service reliability of aeronautical products.
When trends are noted which indicate possible problem areas, the FAA may alert the aviation community or initiate studies to determine the extent and exact nature of the problem.
All aircraft owners, pilots, mechanics, and non-certificated maintenance facilities are invited to participate in the program by submitting 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, maintenance facilities, or any FAA District Office.
If you have had an experience you wish to share, include in the report all information available; how the occurrence became apparent, describe the malfunction, and include model numbers, part numbers, and serial numbers.
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. If you have any questions, or need any help, your local FAA District Office will gladly assist you.
The success of the program depends entirely on participation by the aviation public. If you have comments about the program or have a special experience or a "would you believe this" situation, send them to Federal Aviation Administration, Flight Standards Vational Field Office, Safety Data Branch, 1FS-580, P.O.
Box 23082, Oklahoma City, Oklahoma 73125, 6