AC NO: 20-82 DATE: 5 Dec 72
ADVISORY
CIRCULAR
DEPARTMENT OF TRANSPORTATION
FEDERAL AVIATION ADMINISTRATION SUBJECT: MAINTENANCE INSPECTION NOTES FOR FAIRCHILD HILLER F-27/FH-227 SERIES AIRCRAFT
1. PURPOSE. This advisory circular provides maintenance inspection notes which can be used for the maintenance support program for certain structural parts of Fairchild Hiller F-27/FH-227 series aircraft.
2. REFERENCES.
a. Advisory Circular 20-9, Personal Aircraft Inspection Handbook.
b. Advisory Circular 20-61, Nondestructive Testing Techniques For Aircraft.
c. Advisory Circular 65-9, Airframe and Powerplant Mechanics General Handbook.
d. Advisory Circular 43.13-1, Acceptable Methods, Techniques and Practices - Aircraft Inspection and Repairs.
3. DESCRIPTION. Maintenance inspection matters on the wing, fuselage, empennage, flight controls and landing gear are reviewed, supplementing information currently available.
4. HOW TO GET THIS PUBLICATION.
a. Order additional copies of this publication from:
Department of Transportation Federal Aviation Administration Distribution Unit, IAD-484.3 Washington, D.C. 20591 Initiated by: AFS-230
AC 20- 82 5 Dec 72
b. Identify this publication as: Advisory Circular No. 20-82 Maintenance Inspection Notes for Fairchild Hiller F-27/FH-227 Series Aircraft.
C. R. MELUGIN, JR. Cameluging.
Acting Director, Flight Standards Service Page 2 Par 4
5 Dec 72 AC 20-82
TABLE OF CONTENTS Page No.
CHAPTER MAINTENANCE INSPECTION NOTES 1
1. Preface.
2. Description.
3. Background.
4• General Information.
General Visual Inspection Tips.
6. Nondestructive Testing (NDI).
Definitions.
8. Abbreviations Used In This Document.
CHAFTER 2. WINGS 5 F-27/FH-227 Aircraft Maintenance Information, 5 CHAPTER 3. FUSE LAGE 7
10. FH-227 Aircraft Maintenance Information. 7 CHAPTER 4• FLIGHT CONTROLS 9
11. F-27/FH-227 Aircraft Maintenance Information. 9 CHAPTER 5• LANDING GEAR 11
12. F-27/FH-227 Aircraft Maintenance Information. 11 CHAPTER 6. NACELLES 13
13. F-27/FH-227 Aircraft Maintenance Information. 13 CHAPTER 7. CORROSION-PRONE AREAS 15
14. General 15 .
16. Engine Frontal Areas and Cooling Air Vents.
17. Battery Areas and Vents.
18 • Lavatories, Galleys, and Cabin Floors.
19. Wheel Wells and Landing Gears. 16
20. Control Surface Recesses. 16
21. Spot-Welded Skins. 16
22. Hinges. 16
23. Lap Joints Between Aluminum Alloy Extruded Sections. 17 Page i
Page No•
24. Fluid Entrapment Areas. 17
25. Electronic Package Compartments. 17
26. Control Cables. 18
27. Microbiological Fuel Contamination and Corrosion. 18 CHAPTER 8. MAINTENANCE INFORMATION 19
28. F-27/FH-227 Aircraft Maintenance Information. 19 CHAPTER 9. FH-227 AIRCRAFT WINDSHIELD FRAME 23
29. Magnetization Characteristics. 23 *APPENDIX 1. Outer Wing Panel Fuel Access Door Land. (2 pages) Page ii
5 Dec 72 AC 20-82 CHAPTER 1. MAINTENANCE INSPECTION NOTES PREFACE. This advisory circular provides maintenance information which can be used by mechanics, repair agencies, owners, and operators in developing maintenance programs, making improvements in existing programs, and conducting inspections and repairs on certain structural parts of the Fairchild Hiller F-27/FH-227 series of airplanes. The material is based, in part, upon information made available through discussions with personnel who have maintained these types of airplanes for thousands of hours of time in service.
The intent of the circular is to impart some of this knowledge to other interested persons so that it is not lost.
2. DESCRIPTION. The circular contains guidance material for performing inspection and maintenance on wing, fuselage, empennage, and landing gear structures. The information has been derived from service experience and maintenance publications. Also, there is a listing of selected maintenance difficulties reported during 1970 and 1971.
3. BACKGROUND®
a. Aircraft Use. The agency has realized that several different types of transport aircraft are being phased out of service by some airlines because of the availability of newer equipment.
Such older aircraft are being purchased by other operators who may not be familiar with the scope of required maintenance and the means which have been used to keep the aircraft in a safe and airworthy condition.
Maintenance "Know How." Since maintenance "know how" is not transferred with the aircraft, the new operator generally goes through a learning cycle before he is able to rapidly pinpoint the critical problem areas of the aircraft. In this respect, identification of known areas where structural problems have been experienced will help in the preparation of an initial maintenance inspection program by a new operator. It can also serve as a guide to other operators who have not accumulated sufficient experience to have knowledge of all the problem areas of the aircraft.
4• GENERAL INFORMATION.
a. Manufacturer's Bulletins. It must be emphasized that the manufacturer has published several service bulletins and service letters concerning the inspection, repair, and modification of Fairchild Hiller F-27/FH-227 series aircraft. Service bulletins highlight the importance of maintaining structural integrity on aircraft with particular reference to areas known to have experienced crack and corrosion damage. Service letters may provide maintenance information and will Chap 1 Par 1 Page 1
AC 20-82 5 Dec 72 reference a service bulletin if the information published is serious enough to warrant additional action requiring engineering approval. Operators are urged to become conversant with the manufacturer's recommendations and make certain that responsible maintenance personnel are knowledgeable on this subject.
b• Airworthiness Directive. It is emphasized that the material in this circular does not supersede any of the requirement of airworthiness directives issued under Part 39 of the Federal Aviation Regulations.
GENERAL VISUAL INSPECTION TIPS. The primary structure of the aircraft is designed to provide resistance to variable forces imposed while in operation by dispensing the forces through a structural pattern of 'force flow" to the primary structural members of the wing and fuselage.
External indications of failure, such as distorted skin, tilted or sheared rivets, and torn, dented, cracked, or corroded skin, are usually obvious. Wrinkled skin, "oil cans," and tilted rivets, adjacent to the obviously failed area, often indicate secondary damage caused by transmission of stress from the failed area.
Misalignment of doors and panels may indicate distortion of internal structure. Internal structural damage, although not always apparent, may be found by closely examining the exterior surface. For example:
Buckled skin between rivets at the end of a stiffener or stringer could mean that the last attaching rivet has failed, or that the stiffener or stringer is buckled in the area of the skin buckle.
When a detailed inspection of the failed area is to be performed, functional parts should be actuated to determine if the failure has caused binding.
Deep diagonal skin buckles, located over a frame, former, or rib, could mean the member is distorted. When doubt exists concerning internal condition, the area in question should be opened and carefully inspected.
6. NONDESTRUCTIVE TESTING (NDI). Simply stated, nondestructive testing is preventive maintenance. This includes utilization of such maintenance tools as X-ray, ultrasonic, magnetic particles, eddy current, dye penetrant, and others.
a. Maintenance Inspection. NDI permits maintenance inspections without removing components from aircraft or tearing down complex assemblies.
Training Required. Special NDI training is desirable to make sure that the operator is capable of operating the equipment and interpreting the results. Also, many States require that an X-ray operator have an approved certificate for use of X-ray in industrial applications.
Chap 1 Page 2 Par 4
5 Dec 72 AC 20-82 DEFINITIONS.
Fatigue. The progressive fracture of a metal by means of a fault which develops and spreads under repeated cycles of stress.
b. Stress. The force per unit area of a body that tends to produce a deformation.
c. Stress Raiser. A scratch, groove, rivet hole, forging defect, or other structural discontinuity giving rise to a focal point for a local concentration of stress.
d. Corrosion. Gradual destruction of a material by chemical action which is often evidenced by oxide huild-up on the surface.
8. ABBREVIATIONS USED IN THIS DOCUMENT.
AD Airworthiness Directive F/S Fuselage Station MLG Main Landing Gear NLG Nose Landing Gear P/N Part Number S/B Service Bulletin W/S Wing Station I/B Inboard O/B Outboard N/S Nacelle Station S/N Serial Number Chap 1 Par Page 3 (and 4)
5 Dec 72 AC 20-82 CHAPTER 2. WINGS
9. F-27/FH-227 AIRCRAFT MAINTENANCE INFORMATION. Following is a listing of significant maintenance difficulties that have been reported by air carriers. In addition, a number of check and inspection items are listed. This information may be useful in identifying structural inspection areas. Except where noted, wing structural references apply to both left and right wings.
a. Center Wing.
(1) Skin. Lower wing skin cracks have been detected at stringers No. 4 and No. 8 in area of stringer joggles near W/S 68.
(2) Skin. Cracks have been found in the lower wing skin O/B of the center wing to fuselage fitting at the rear spar near W/S 24.
Rib. Cracks have occurred in lower rib flange to stringer attachments at stringers No. 1 through No. 11 near W/S 79.
Stringers. Lower stringers No. 1 through No. 11 have been found cracked on both sides of rib at W/S 20.
Stringers. Lower stringers No. 4 and No. 6 have been found cracked on both sides of rib at W/S zero.
Skin and Stringers. Lower wing skin and stringers No. 5, No. 6, and No. 7 have been found cracked near W/S 64.
Skin. Lower wing skin and external finger strip splice cracks have occurred between the front and rear spar near W/S 55.
Stringer. Cracks have been found in stringer No. 5 at the end of the angle splice near W/S 67.
(9) Skin and Spar. Cracks have occurred in the lower wing skin and in horizontal leg of the front spar cap and splice strip, and the lower skin at the rear spar near W/S 37.
(10) Access Doors. Lower skin access doors have been found cracked.
These doors are located between W/S 80 and 100.
Spar Web. Verticle cracks have occurred in the front spar web at the lower spar cap just 0/B of the stiffener near W/S 89.
(12) Skin. Check for cracks in skin emanating from under the fuselage-to-wing attach fittings and extending forward and aft at W/S 20.
Chap 2 Par 9 Page 5
(13) Spars. Check for cracks in the radius of the lower connecting strip at the front and rear spar near W/S 24.
Cracks in these areas will probably extend I/B then turn forward.
(14) Spar Webs. Check for vertical cracks in front and rear spar webs at the lower spar caps at W/S 22.
(15) Spar. Check for cracks in the rear spar and doubler near W/S Zero.
Engine Mount Support. Cracks have occurred in engine mount upper tube P/N 27-503105-11, -31, -41 and 01-503105-11 or -31; lower tube P/N 27-503101-11, -41, -51, -61, -71, -81, -91, -101 or -111; and upper bracket P/N 27-110105-11, -12, -31, -32, -41, -42, -51, -52, -61, -71, -72, -81, or -82.
Ref. Fairchild Hiller S/B F-27 54-14 revision No. 2 dated February 1969, and FH-227 54-4 revision No. 1 dated February 1969) * b. Outer Wing Panels. (See Appendix l.) *
(1) Doors. Cracks have been found at the attach screw holes of No. 1 inspection door opening near W/S 195 and 205.
(2) Do 2 inspection Check for cracks at the attach screw holes of the No. 2 inspection door opening near W/S 240 and 250.
(3) Doors. Check for cracks at the attach screw holes of the No. 3 inspection door opening near W/S 292 and 302.
(4) Doors. Check for cracks at the attach screw holes of the No. 4 inspection door opening near W/S 335 and 345.
(5) Door and Stringers. Check for cracks in lower skin, access door land, and stringers, at W/S 194, 197, and 204.
Chap 2 Page 6 Par 9
5 Dec 72 AC 20-82 CHAPTER 3. FUSELAGE
10. FH-227 AIRCRAFT MAINTENANCE INFORMATION. Following is a listing of significant maintenance difficulties that have been reported by air carriers. In addition, a number of check and inspection items are listed. This information may be useful in identifying structural inspection areas. Except where noted, fuselage structural references apply to both left and right sides of the fuselage.
a. Windshield Post Fitting. Check windshield post attach fitting and aft side of bulkhead web at F/S 55 for cracks.
b. Forward Bulkhead. Check front bulkhead web through nose wheel well in areas of fittings for evidence of cracks.
Fuselage Tail Section. Cracks have been reported in the skin around the louvers of the aft fuselage tail section. (Ref.
Fairchild Hiller S/B FS-227 53-9 dated 8 June 1967.)
d. Top Fuselage - Cables. Operators have reported a chafing condition between control cables and fuel crossfeed-water methanol lines at F/S 298. (Ref. Fairchild Hiller S/B FH-227 53-8 revision No. 2 dated 23 October 1969.) Applies to aircraft serial numbers 501 through 549.
e. Lower Fuselage Skin. Cracks have been found in the lower fuselage skin between stringers No. 7 and No. 8 left, and stringers No. 44 and No. 45 right, from F/S 198 to 510. (Ref. Fairchild Hiller S/B F-27 53-48 dated 21 March 1967.) Aircraft with serial numbers 20 and above were modified by the manufacturer prior to delivery.
Chap 3 Par 10 Page 7 (and 8)