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)
5 Dec 72 AC 20-82 CHAPTER 4. FLIGHT CONTROLS F-27/FH-227 AIRCRAFT MAINTENANCE INFORMATION. The following is a listing of significant maintenance difficulties that have been reported by air carriers. This information may be useful in identifying structural inspection areas. Except where otherwise indicated, flight control structural references apply to left and right sides.
For details and inspection requirements, each item references pertinent service bulletins, and/or service letters.
a. Rudder and Elevator Tension Regulator. Loose rivets have been found in the rudder and elevator tension regulator. P/N 0501101-0 or 051101-1. (Ref. Fairchild Hiller S/B F-27 27-16 revision No. 2 dated 20 April 1960). Applies to aircraft with serial numbers 1 through 64.
b. Wing Flap Jackscrew Gimbal Nuts. Failure of the gimbal nuts, P/N 27-165012-3, -4, -5, -6, and 27-175023-3, -4, have occurred which render the gimbal nuts unsafe for further use. (Ref.
Fairchild Hiller S/B F-27 27-18A dated 27 October 1959 and 27-28 revision No. 3 dated 22 August 1961).
c. Aileron Control Sectors. Corrosion has been found on magnesium aileron control sectors, P/N 27-727207-21, 27-727208-21, 27-727209-21, 27-727300-21, and 27-727381-21, with two or more years' time since installation. (Ref. Fairchild Hiller Service letters F-27 306 dated 22 August 1963, 307 dated 17 September 1963, and 311 dated 12 April 1965).
d. Horizontal Stabilizer - Upper and Lower Surfaces. Cracks have been found in the skin, stringers, and rib caps. (Ref. Fairchild Hiller S/B F-27 55-6 revision No. 7 dated 1 May 1970, 55-7 dated 20 July and FH-227 55-9 dated 7 July 1969).
e. Horizontal Stabilizer Front Spar. Operators have reported cracks in the front spar web and the upper and lower spar caps between stabilizer stations 95.45 and 125.98. (Ref. Fairchild Hiller S/B F-27 55-7 dated 20 July 1965.
f. Rudder Horn. Cracks have been detected in the rudder horn, P/N 27-243018-11.
g. Horizontal Stabilizer Upper I/B Surface. Cracks have been found in the upper skin between stabilizer stations 0 to 30 from the front spar aft to stringer No. 10. (Ref. Fairchild Hiller S/B FH-227 55-1 revision No. 1 dated 17 November 1966, and F-27 55-11 revision No. 1 dated 17 November 1966).
Chap 4 Par 11 Page 9
AC 20-82 5 Dec 72 Horizontal Stabilizer Rear Spar Fittings. Operators reported cracks in the rear spar fittings, P/N 27-210501-3, -4, -5, -6.
(Ref. Fairchild Hiller S/B FH-227 55-17 dated 10 February 1969).
Rudder Skin, Stiffeners, and Rear Spar. Cracks have been found in the rudder skin and stiffeners and cracks may occur in the rear spar flange. Skin should be inspected from rudder stations 10 to 71 between the center and rear spars. The stiffeners at rudder stations 16, 28, 40, 52, and 64 between the center and rear spars should also be checked for cracks. (Ref. Fairchild Hiller S/B's FH-227 27-4 revision No. 1 and F-27 27-42 revision No. 1, both dated 28 February 1967).
j. Elevator Trim Tab. Failures of elevator trim tab, P/N 01-223008-1, have been reported on at least two occasions. (Ref. Fairchild Hiller Alert S/B FH-227 27-17A dated 8 Jamuary 1968).
Chap 4 Page 10 Par 11
5 Dec 72 AC 20-82 CHAPTER 5. LANDING GEAR F-27/FH-227 AIRCRAFT MAINTENANCE INFORMATION. The following is a listing of significant maintenance difficulties reported by air carriers. This information may be useful in identifying structural and other inspection areas. Except where noted, the items listed refer to left and right sides. For details and inspection requirements, each item references pertinent service bulletins, and/or service letters.
Main Landing Gear Drag Strut Bolts. Several failures of drag strut attach bolts, P/N 9017Y11 and 9027X7, have occurred on aircraft that have accumulated 300 or more landings. (Ref.
Fairchild Hiller S/B F-27 32-44 revision No. 2 dated 19 January 1962).
b. Main Landing Gear Outer Cylinder Torque Link Attach Lugs.
Failures of attach lugs, to which upper torque link, P/N C9027Y3, is attached, have occurred on aircraft that have accumulated 8000 or more landings. (Ref. Fairchild Hiller S/B F-27 32-41A dated 5 April 1961, Dowty Service Bulletins 32-11 dated August 1961, revised December 1962; and 32-15 dated October 1961).
c. Main Landing Gear Drag Strut. Cracks have been detected in main landing gear drag strut assemblies, P/N 2-00259-002, with 500 hours or more time in service.
do Nose Steering Actuator Mount Bolts. Failures of mounting bolts, P/N 244241 and 245804, in the NLG pivot bracket have been reported. (Ref, Walter Kidde Service Bulletin No. 143 dated October 1962)
e. Nose Gear Door Rods. Operators have reported binding of the nose gear door actuating swivel rods. Aircraft with serial numbers 251 and later have been modified by the manufacturer to improve lubrication. (Ref. Fairchild Hiller S/B FH-227 32-3 dated 20 December 1966).
Unselected Gear Retraction. Reports of unselected landing gear retraction on the ground resulted in a change of wiring in the landing gear system. The change was incorporated during the manufacture of aircraft with serial numbers 541 and later.
(Ref. Fairchild Hiller S/B FH-227 32-5 dated 13 March 1967).
Chap 5 Par 12 Page 11 (and 12)