# AC 20-64: [Large AC] Maintenance Inspection Notes for Lockheed L-188 Series Aircraft - Type: Advisory circular (guidance, not mandatory unless a rule or AD requires it) - Status: Historical - Approved: August 1, 1969 - Last reviewed: October 27, 2016 - Family: AC 20-64 - 14 CFR parts: Unknown Part - Pages: 97 - PDF: https://openairdocs.org/files/sha256/6f/43/6f434c978fe936ba8d2d2c28a7b3e418e29accc39d497275df77ec8c50aa60c4 - FAA DRS: https://drs.faa.gov/browse/excelExternalWindow/0363792AEB3C06F1862569D600786B93.0001 - DRS record last changed: October 27, 2016 - Page: https://openairdocs.org/ac/20-64 ## Versions - [AC 20-64](https://openairdocs.org/ac/20-64) (Historical), approved Aug 1, 1969, 97 pages ## Text Each page's text from the PDF; open the PDF at a page with #page=N. This is OCR from the scanned FAA advisory circular. OCR can misread letters and numbers. ### Page 1 (OCR) 0014073 AC NO: AC 20-64 DATE: 8/1/69 EDERAL AVIATION ADVISORY * MINISTRATIO CIRCULAR **DEPARTMENT OF TRANSPORTATION** FEDERAL AVIATION ADMINISTRATION SUBJECT: MAINTENANCE INSPECTION NOTES FOR LOCKHEED L-188 **SERIES AIRCRAFT** 1. PURPOSE. This handbook describes maintenance inspection notes which can be used for the maintenance support of certain structural parts of Lockheed L-188 series aircraft. This is one of a series of Advisory Circulars to be published on existing aircraft to assist maintenance personnel in directing their attention to those areas which, in addition to normal maintenance practices, have been shown to require special attention. 2. DESCRIPTION. Maintenance on the wing, fuselage, empennage, flight controls, and landing gear structure is reviewed with a view toward supplementing information currently available. **3. 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. 20590 b. Identify this publication as: Advisory Circular 20-64 Maintenance Inspection Notes for Lockheed L-188 Series Aircraft. adung Flight Standards Service Director, Initiated by: AC-230/FS-320 ### Page 2 (OCR) AC 20-64 8/1/69 TABLE OF CONTENTS Page No. **CHAPTER 1. MAINTENANCE INSPECTION NOTES. 1** 1. Introduction. 2. Description. 3- Background. 4. General Information. Type of Construction. General Visual Inspection Tips. Nondestructive Testing (NDI). 8. Aircraft Station Diagrams. 9. Definitions. 10. Abbreviations Used In This Document. 4 CHAPTER 2. WING. 5 11. I-188 Aircraft Maintenance Information. 5 CHAPTER 3. FUSELAGE. 9 12. I-188 Aircraft Maintenance Informatim. 9 CHAPTER 4. FLIGHT CONTROLS. 11 13. L-188 Aircraft Maintenance Information. 11 CHAPTER 5. LANDING GEAR. 14. I-188 Aircraft Maintenance Information. 13 CHAPTER 6. CORROSION PRONE AREAS. 15 15. General. 16. Exhaust Trail Areas. 17. Engine Frontal Areas and Cooling Air Vents. 18. Battery Areas and Vents. 19. Lavatories, Galleys, and Cabin Floors. 20. Wheel Wells and Landing Gears. 21. Control Surface Recesses. 22. Spot-Welded Skins. 23. Hinges 24. Lap Joints Between Aluminum Alloy Extruded Sections. 16 25. Fluid Entrapment Areas. 17 26. Electronic Package Compartments. 17 27. Control Cables. 17 28. Microbiological Fuel Contamination and Corrosion. 18 ### Page 3 (OCR) AC 20-64 CHG 1 10/26/73 Page No. **CHAPTER 1. MAINTENANCE INFORMATION. 19** 29. L-188 Aircraft Maintenance Information. 19 APPENDIX 1. STATION CHARTS. (1 page) Figure A-l. Basic Dimensions. APPENDIX 2. WING STATION CHARTS. (3 pages) Figure B-l. Wing Station Diagram. Figure B-2. Wing Skin Planks and Material Index. Figure B-3. Wing Access and Inspection Provision. APPENDIX 3. NACELLE STATION CHARTS. (1 page) Figure C-1. Nacelle Station Diagram. 1 APPENDIX 4. FUSELAGE STATION CHARTS. (4 pages) Figure D-l. Fuselage Stations Diagram (Serial Nos. 1001 and Up). 1 Figure D-2. Fuselage Stations Diagram (Serial Nos. 2001 and Up). Figure D-3. Fuselage Contour Coordinates. Figure D-4. Fuselage Canted Section. 4 APPENDIX 5. STABILIZER STATION CHARTS. (3 pages) Figure E-l. Stabilizers Stations Diagram. Figure E-2. Horizontal Stabilizer Stringer Identification. Figure E-3. Horizontal Stabilizer Stringer Identification. 3 * APPENDIX 6. MAINTENANCE NOTES FOR WING STRUCTURAL AREAS. (57 pages) 1 Figure F-1. Wing Section Upper Surface. Figure F-2. Wing Section Lower Surface. Figure F-3. Service Problem Areas. Figure F-4. Wing Upper Surface• 29 Figure F-5. Wing Upper Surface. Figure F-6. Wing Lower Surface. Figure F-7. Wing Lower Surface. 32 Figure F-8. Wing External Structure. 33 Figure F-9. Wing Internal Structure. Figure F-10. Wing Lower Surface. Figure F-ll. Wing Upper Surface. 36 Figure F-12. Wing Upper Surface. 37 Figure F-13. Wing Upper Surface. 38 Figure F-14. Wing Upper Surface. 39 Figure F-15. Wing Upper Surface. 40 Figure F-16. Wing Upper Surface. 41 Figure F-17. Wing Upper & Lower Surface. 42 ### Page 4 (OCR) AC 20-64 CHG 1 10/26/73 Page No. Figure F-18. Wing Upper and Lower Surface. 43 Figure F-19. Wing Lower Surface. 44 Figure F-20. Wing Lower Surface. 45 Figure F-21. Wing Internal Structure. 46 Figure F-22. Wing Lower Surface. 47 Figure F-23. Wing Lower Surface. 48 Figure F-24. Wing Internal Structure. 49 Figure F-25. Wing External Structure. 50 Figure F-26. Wing External Structure. 51 Figure F-27. Wing Internal Structure. 52 Figure F-28. Wing Upper Surface. 53 Figure F-29. Wing Lower Surface. 54 Figure F-30. Wing Lower Surface. 55 Figure F-21. Wing Upper Surface. 56 Figure F-32. Wing Upper & Lower Surface. 57 ### Page 5 (OCR) AC 20-64 Page 1 8/1/69 CHAPTER 1. MAINTENANCE INSPECTION NOTES 1. INTRODUCTION. 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 Lockheed I-188 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. DESCRIPITON• The circular contains guidance material for performing inspection and maintenance on wing, fuselage, empennage, flight controls, and landing gear structures. The information has been derived from service experience. It does not comprise a full and complete maintenance program for the subject aircraft but should be considered as supplemental maintenance data. Included in the circular are diagrammatic sketches and station identifications of the wing, fuselage, and flight controls. In addition, there is a listing of selected maintenance difficulties which have been reported during 1967 and 1968. **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. b. 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 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 concerning the inspection, repair, and modification of Lockheed I-108 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. Operators are urged to become conversant with the manufacturer's recommendations and make certain that responsible maintenance personnel are knowledgeable on this subject. Chap 1 Par 1 ### Page 6 (OCR) Page 2 AC 20-64 8/1/69 b. Airworthiness Directive. It is emphasized that the material in this circular does not supersede any of the requirements of airworthiness directives issued under Part 39 of the Federal Aviation Regulations. TYPE OF CONSTRUCTION. The major structural components of the aircraft are the wing group, the fuselage group, and tail group. The primary structure, shown in detail in this manual, consists of the fuselage, nacelles and the box beam sections of the wing and the vertical and horizontal stabilizers. These components have been designed in accordance with the "fail safe" policy. This policy provides multiple load paths and reduced stress levels, such that a single failure of any structural element will not result in the loss of the complete structural component. a. The wing is an all-metal, full cantilever-type structure and consists of a center section, an outer section, flaps, fillets and ailerons. The primary structure of the wing incorporates two main beams, upper and lower extruded surface panels, and ribs to stabilize the structure and maintain surface contour. Wing flaps are actuated by ball-bearing screw jacks and travel on steel tracks. The internal structure and skins are fabricated of aluminum alloy. Ailerons and trim tabs are of conventional design and constructed of aluminum alloy. Leading edges are attached to the front beam by hinges and incorporate provisions for ice elimination. Trailing edges are fabricated by the use of the metal-bond process, an outside skin bonded to an inner beaded skin. A major portion of the lower trailing edge is sectioned into hinged doors for inspection and maintenance. b. The fuselage is of conventional semimonocoque construction, using skin, stringer, and circumferential-irame combinations. The skin Large doublers, made of the same materials and usually chem-milled'¿p panels, for the most part, are made of 2024-T3 or -T4 material. are used around doors, windows, and, generally, around all cutouts the skin. The frames from station 200 to 1110 are mainly 19 inches apart with reinforced structure in the propeller and door areas. Stringers are made, for the most part, oi formed sheet-metal sections, except near openings where heavier extruded sections are used. The floor support structure consists mainly of extruded vertical and transverse members attached to the fuselage frames. In the center section (over the wings) and in the nose section, longitudinal beams support the floor. Floor panels are of plywood in the aisles and vestibules, and metal-honeycomb-sandwich elsewhere. The latter contains electric-heating elements in passenger seating areas. The entire fuselage is pressurized between the forward pressure bulkhead (forward of and below the flight station) and the rear pressure bulkhead (rear of the lounge or aft lavatory). The main manufacturing joints are at stations 200 and 1117. Along the main passenger compartment from station 219 to approximately 968, the fuselage is a constant section. Par 4 Chap 1 ### Page 7 (OCR) AC 20-64 Page 3 8/1/69 The stabilizers consist of the horizontal stabilizer and tips, elevator and tabs, vertical stabilizer and tip, rudder and tab, fillets, and dorsal. Each member has an all-metal aluminum frame covered with aluminum skin. The horizontal stabilizer 1s attached to the fuselage tail section by four continuous beam caps and four continuous stringers. The vertical stabilizer is attached to the fuselage tail section by the extension of four beam caps and four stringers. The dorsal is connected to the fuselage by means of an attaching angle. There is a shear pin that connects the top of the dorsal to the vertical stabiiizer at fuselage station 1117. 6. GENERAL VISUAL INSPECHION TIPS. The primary structure of the aircraft 18 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 obvious. Wrinkled skin, shelous. Veiled in, ole, and tited vets, 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. b. 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. 7. NONDESTRUCTIVE TESTING (NDI). Simply stated, nondestructive testing 18 preventive maintenance. This includes utilization of such maintenance tools as X-ray, ultrasonic, magnetic particles, eddy current, dye penetrant, and others. Maintenance Inspection. NDT permits maintenance inspections without removing components from aircraft or tearing down complex assemblies. Defects in various aircraft systems which would escape detection through normal visual inspection can be identified by NDI. b. Training Required. Special NDI training 1s desireable 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 Chap 1 Par 5 ### Page 8 (OCR) Page 4 AC 20-64 8/1/69 have an approved certificate for use of X-ray in industrial applications. This is to minimize improper use with attendant health hazard of X-ray equipment. 8. AIRCRAFT STATION DIAGRAMS. The wing, fuselage, and empennage station diagrams included in this document were developed for the I-188 aircraft and are used as a general reference only. Several models of these aircraft were manufactured and have different station locator numbers based on the particular configuration. Since the defective areas generally apply to all models of aircraft, the referenced area can be compared with a similar area and locator on the appropriate station diagram for the particular model of aircraft. (See Appendices 1 through 5.) **9. 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. 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. Often evidenced by oxide buildup on the surface. **10. ABBREVIATIONS USED IN THIS DOCUMENT.** AD Airworthiness Directive F'BC Fixed base check FCD Fleet campaign directive FS Fuselage station HSS Horizontal stabilizer station LAC Lockheed aircraft MBC Main base check MLG Main landing gear NIG Nose landing gear P/N Part number SB Service Bulletin SIL Service Information Letter Total time TAT Total aircraft time TSN Time since new TSO Time since overhaul T ST Total ship time VSS Vertical stabilizer station WS Wing station Par 7 Chap 1 ### Page 9 (OCR) AC 20-64 Page 5 8/1/69 CHAPTER 2. WING 11. L-188 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 noted, wing structural references apply to both left and right wings. Lockheed Reference a. Lower Wing Skin Planks. For Details (1) Lower wing skin plank damage was caused SIL-61 by integral engine start system compressor 10/17/62 line rubbing in #2 and #3 nacelles. (2) Cracks occurred in the lower #3 wing skin SB 601 plank forward of the MG fulcrum fitting. 6/24/63 (Over 900 hours TSN.) (3) SB 587 alert wire was issued to inspect #4 SB 587A lower wing plank drain hole for cracks at 4/10/64 station 159. Plus AD 65-15-4 (4) Cracks have been found at the fastener holes SB 631 around the fuel sight gage and fuel overflow 9/6/65 openings on the left- and right-hand lower wing planks. The cracks occur at wing station 128.0 and in the wing reinforcing doubler at station 266.0. (5) Cracks have been found in lower wing plank #1 SB 653 between WS 205 and WS 275. 7/3/68 b. Upper Wing Skin Planks. (1) Cracks have been found which appear to be SB 565 static fractures originating on the #l 4/27/62 upper wing plank inner surface. (2) Cracks have been found in the upper surface SB 619A in the area of the main landing gear rib 5/21/65 forgings. These areas were previously rein- Plus AD forced by doublers in accordance with SB 65-9-4 306 and 337 except aircraft, LAC serial #1145 thru 1148 and 2020-2022, which were delivered with internal reinforcements. Chap 2 Par 11 ### Page 10 (OCR) Page 6 AC 20-64 8/1/69 (3) Cracks have been found at screw holes 1n the SB 632 wing upper plank #2, at the plank #1 and #2 6/29/65 splice between WS 212.0 and 230.0. Cracks have been found in the trailing edge of SB 634A wing planks #6, #7, and #8 at wing station 143 10/8/65 LEFT and RIGHT upper surface. In two cases, the backup fitting, P/N 803900, for the flap track attachment was also cracked. (5) This reference applies to the inspection of SB 6250 wing plank splices aft of the main landing 5/16/66 gear fulcrum fitting and provides additional Plus AD repair 1nstructions for the WS 209 area (see 66-11-2 d(2) page 7). This revision provides instructions to reduce SB 600A the possibility of cracks developing in the 2/21/68 upper wing planks under the nacelle skate Plus AD The original bulletin pertained only 64-11-3 to the inboard nacelle skate angles, but this revision supplies reinforcement for ALL (7) A considerable number of cracks have been found SB 649 in the #l upper wing plank at the nacelle 2/29/68 fillet attachments. Cracks have been found at SB 665 the inboard side of all four nacelles at the Plus AD's attachment of the nacelle fillet with the 68-11-2 upper #1 plank. 68-23-5 (8) Cracks have been found in the #3 upper wing SB 652 plank along the first row of fasteners 4/30/68 adjacent to the skate angle of the outboard nacelle at WS 346.0. c. Outer Wing to Center Wing Attach Fittings. This SB revisionwas issued to identify SB 633A/633B requirements for the outer wing front cap fittings, 9/3/65 8 P/N 807352 and P/N 807354; specifically, corrosion 9/24/65 of fittings, attachment bolts, and boltholes. Plus AD 66-5-3 d. Wing - MG Ribs. These service bulletins instruct operators as follows: (1) To inspect the MG ribs in each wing for SB 630 fatigue cracks in the web fillets at the 7/20/65 junctures of the rib truss members with the rib upper chord member. Similar cracks Par 11 Chap 2 ### Page 11 (OCR) AC 20-64 Page 7 (and 8) 8/1/69 have also been found in the web fillet between the forward truss member and the upper chord member beneath the #? wing plank. (2) To inspect the vertical legs of the upper and SB 639 lower caps of the wing ribs for cracks at 11/7/66 wing stations 167 and 209. Wing-to-Nacelle Attachment Plate. Cracks have been SB 638 found in the wings-to-nacelle attachment plate, 10/17/66 P/N 810054-1, which is located inside the inboard nacelle on the lower front beam of the LEFT WS 209. (Propeller torque loads on the #2 nacelle augment the normal stresses on this plate.) f. Wing Rear Beam Clips. Cracks have been found in P/N SB 654 805483-1 (WS 179), and P/N 805491-1 (WS 197) rib 4/8/68 attach clips location (dry bay area), at the rear beam forward face upper attachment. Cracks occur in the 0.16 radius of the flange relief cutout and extend toward the nearest fastener hole. & - Wing Upper and Lower Access Door Lands. Corrosion SB 606 found on the lower wing plank access door lands 11/18/63 appears to be caused by condensation. (Door lands are the area surrounding the access opening in the wing plank.) Chap 2 Par 11 ### Page 12 (OCR) AC 20-64 Page 9 8/1/69 CHAPTER 3. FUSELAGE 12. I-188 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 noted, fuselage structural references apply to both left and right sides. Lockheed Reference a. Fuselage Stringers Station #1117. This For Details service bulletin provides for inspection SB 574 of the underfloor stringers at the aft 10/3/62 pressure bulkhead for cracks. The Revised 12/26/62 bulletin was later revised to cover all underfloor stringers, 1 thru 72. b. Flight Station Pressure Deck. Cracks have SB 609A been found in the flight station pressure 11/2/63 deck structure, butt line 40 right beam, Revised 3/30/65 lower beam cap flange. Cracks in this location could result in a loss of cabin pressure. Reported cracks have occurred on aircraft with over 13,000 total flight hours. Forward and Aft Cargo Door Frame Corners. SB 608A Cracks have been found in the lower forward 2/5/65 and aft cargo door frames. Revised SB 608B 2/18/65 d. Fuselage Main Frame Fittings. A considerable SB 644 number of cracked main frame fittings have 2/10/67 been found at FS 570 and FS 695 Revised SB 644A 12/5/67 Plus AD " 67-11-4 Fuselage Bulkhead Ring Intersection with Center SB 646 Wing. Cracks have been found at the intersection 4/12/68 between the wing center section lower surface and the fuselage rings at fuselage stations 571 and 694. f. Cabin Window Support Structure. Cracks have SB 647 been found in fuselage station 853.5, (cabin 5/6/68 window support structure.) Chap 3 Par 12 ### Page 13 (OCR) Page 10 AC 20-64 8/1/69 g. Canted Fuselage Frame Upper Web. Cracks have been SB 579 round in the canted frame upper web, station 1167.7. 1/31/63 (See figure D-4 in appendix 4, page 4.) Revised SB 579A 6/17/68 Plus AD 63-17-3 Par 12 Chap 3 ### Page 14 (OCR) AC 20-64 Page 11 8/1/69 CHAPTER 4. FLIGHI CONTROLS 13. I-188 AIRCRAFT MAINTENANCE INFORMATION. The following 18 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 noted, flight control structural references apply to both left and right sides. Lockheed Reference For Details a . impennage. (1) Elevator Counterweight Installation. SB 457 Excessive cumulative free play has been 7/15/60 found in the joints of the elevator counterweight balance arm linkages. (2) Empennage Drain Hole. This service bulletin SB 573 was issued to prevent moisture accumulation 9/26/62 in the empennage by providing improved drainage. (3) Canted Fuselage Station 1167.7 Frame Upper SIL-62 Web. Cracks have been found on both sides 11/17/62 of horizontal stabilizer station 29 at the lower cap in the 0.62-1nch radius. (4) Rudder Trailing Edge. Cracks have been found SB 602 in the outer skin and beaded inner skin of the 7/3/63 rudder trailing edge. Cracks starting from holes at the aft end of the beads weaken the structure and cause additional cracks to develop in the outer skin at the spotwelds. Spotwelds that may crack are located 1½ to 2 inches forward of the rudder trailing edge. (5) Vertical Stabilizer to Fuselage Attach Channel. SB 616 Cracks have been found in the vertical 7/24/64 stabilizer to fuselage attach channel, P/N Revised SB 616A 803179-5, located at fuselage station 1117.6. 4/5/65 Plus AD 65-21-5 (6) Elevator Balance Weight Arms and Ribs. This SB 567 modification will eliminate repeated inspec- Revised 5/9/62 tion of the elevator balance weight arms SB 567C (for cracks), required by the original SB 7/30/65 567, revision 1, dated 12/3/62. Chap 4 Par 13 ### Page 15 (OCR) Page 12 AC 20-64 8/1/69 b. Ailerons. Aileron Skin Doublers. Cracks have been SB 444 found in the lower aileron skin between 5/27/60 the trim tab actuating rod access door and the rear beam, notably in the area where the forward and aft flanges of the internal beaded doublers mate with the skin. (2) Aileron Counterbalance Attaching Angles. SB 451 Cracks have been found in the aileron 5/10/60 counterweight attaching angles. Revised 7/25/60 Plus AD 60-25-2 (3) Aileron Push-Pull Tubes. Cracks have been SB 607 found in the aileron push-pull tubes, a.so 10/17/63 wear, and misalignment of the support Plus AD assemblies and rollers. 64-16-4 c. Flaps. (1) Wing Flap Torque Tubes. Operators have SB 570 reported flap torque tube support bearings 6/20/62 binding and/or rubber sleeves deteriorated or missing. This results in torque tube wear caused by this tube turning in the inner race of the P/N KP16BS bearing. (2) Wing Flap Track Attaching Bolts. Operators SB 591 have reported extensive damage to a flap 4/3/63 due to the failure of the outboard lower Revised SB 591A flap track attach bolts. 1/7/64 Par 13 Chap 4 ### Page 16 (OCR) AC 20-64 Page 13 (and 14) 8/1/69 CHAPTER 5. LANDING GEAR 14. I-188 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 noted, structural references on the main landing gear (MIG) refer to both left and right gears. Lockheed Reference For Details a. Main Landing Gear Actuator Support Fittings, SB 599A Cracks have been found in the MIG actuator 10/22/63 support fittings, P/N 800618. b. Main Landing Gear Actuating Cylinder Attach SB 593A Fitting Intercostal. During accomplishment of 7/12/63 SB 538, a crack was found in the wing plank SB 593B surface of one aircraft and a crack in the wing 1/24/64 plank riser of another aircraft. Both cracks Plus AD were located under the MG actuator cylinder 64-14-5 attach fitting. Nose Landing Gear Steering Housing. Cracks have SB 576 been found in the nose landing gear steering 10/29/62 housing. These housing cracks originate at the Revised 4/8/63 inboard end of the 4-1/8" - 12 UNS-3A screw thread SB 576B that receives the retaining nut of the steering 3/17/64 cylinder. The cause is attributed to fatigue Plus AD failure of the thread root. 66-28-4 d. Nose Landing Gear Assembly Trunnion Locking SB 604 Slots. Cracks have been found in the fulcrum 10/18/63 bearing spacer locking slots in the NIG LEFT Revised SB 604B trunnion arm. 6/29/65 e. MIG High Heat Treat Steel Plating and Stripping SIL-88 Practices. Landing gear shock strut components 7/25/66 have failed in service after passing through major overhaul and replating procedures. f. Main Landing Gear Lubrication. This SIL outlines SIL-32 revised maintenance procedures and improved 5/23/62 lubricants for landing gear static and dynamic joint corrosion protection. Chap 5 Par 14 ### Page 17 (OCR) AC 20-64 Page 15 8/1/69 CHAPTER 6. CORROSION PRONE AREAS GENERAL. Corrosion is most likely to strike at the joints or attachment points in metallic structure because they provide entrapment areas for corrosive agents and moisture to accumulate. However, the problem can be compounded if metallic surfaces are exposed to an extremely corrosive environment, or if the surfaces are difficult to inspect and clean. The most important corrosion preventive measure is to keep them clean and dry. 16. EXHAUST TRAIL AREAS. Both jet and reciprocating engine exhaust deposits contain compounds that are very corrosive, and the structure in the path of exhaust gas is more likely to suffer from corrosion than is any other structure. It is customary to coat structure exposed to exhaust gases with protective finishes to prevent these gases from coming in direct contact with the metal. However, the deposits which collect on top of the protective finishes must be removed before they permeate the film and attack the metal. Most troublesome are those areas where exhaust gas deposits may become entrapped and cannot be reached by normal cleaning methods. Typical of these areas are seams, gaps, hinges, or fairings located in the exhaust gas path. 17. ENGINE FRONTAL AREAS AND COOLING AIR VENTS. These areas are subject to erosion by airborne contaminants, rain, and from foreign objects on the runways. Erosion will remove the protective finishes or oxide film from the metal surfaces, leaving them vulnerable to corrosive attack. In addition, much of the equipment installed within these recesses is also vulnerable to corrosion. When an aircraft is operated in a marine environment, salt deposits may accumulate in these areas and the ensuing corrosive attack can be rapid and destructive. It is imperative that these areas be frequently inspected and cleaned, and protective finishes be maintained. BATTERY AREAS AND VENIS. Due to the highly corrosive nature of battery acid (sulfuric acid) and its fumes, battery areas and their vents are protected by special acid-resistant paints. Generally this is enough to stem the tide of corrosion if scrupulous attention is devoted to keeping LAVATORIES, GALLEYS, AND CABIN FLOORS. The usual spillage, condensation, and other contamination of these areas are extremely corrosive to aircraft metals. The most common corrosive agents are acidic foods and beverages, and human excreta. Also, most chlorinated disinfectants are acidic and corrosive, and cannot be recommended for use in aircraft. It is impractical to assume that these areas can be kept clean and dry at all times, but it is important to inspect the structure carefully at suitable intervals, cleaning and renewing the finish as necessary. Areas behind lavatories, sinks, or ranges where waste may collect are potential trouble spots, as are personnel relief and waste disposal vents or openings on the exterior of the aircraft. Chap 6 Par 15 ### Page 18 (OCR) Page 16 AC 20-64 8/1/69 20. WHEEL WELLS AND LANDING GEARS. Equipment installations in the wheel well areas probably absorb more punishment than any other portion of an aircraft because they are exposed to moisture of flying debris during takeoffs and landings, and when the aircraft is parked they are exposed to atmospheric moisture. After an airplane has entered service, it is difficult to maintain protective paint film on landing gears, equipment installations, and wheel well surfaces because the many complicated shapes, assemblies, and fittings in these areas obscure other surfaces. Items that should receive special attention during wheel well inspections are: a. Magnesium wheels (especially the areas around the bolt heads, lugs, and wheel webs). b. Portions or rigid tubing obscured by clamps and identification tapes. c. Exposed electrical equipment. d. Crevices between ribs, stiffeners, and lower skin surfaces which can serve as water or debris entrapment areas. Corrosion control in wheel well areas may best be attained by frequent cleaning, lubrication, paint touch-up and judicious use of wheel covers. CONTROL SURFACE RECESSES. Control surface recesses are potential problem areas because normally they are difficult to inspect. If corrosive agents gain entry and accumulate in these areas, they may go unnoticed for some time. Frequent inspection and cleaning of the surfaces and installations located in these recesses will prevent corrosion from gaining a foothold. 22. SPOI-WELDED SKINS. c'orrosive agents may become entrapped between the layers of metal adjacent to the spot-weld beads. If moisture enters the area, an electrolytic cell can be set up between the dissimilar metal phases in the spot-weld area, and one or more of these phases will be subject to preferential corrosive attack. Whenever practical, structural areas with spot-welded assemblies should be sealed to prevent the ingress of contaminants and moisture. 23. HINGES. Hinges are natural traps for corrosive agents. Often they are susceptible to galvanic corrosion when the hinges and pins are made of dissimilar metals. The most practical means of corrosion control is to inspect and lubricate hinges frequently. After lubrication, actuation of the door through several cycles is necessary to ensure complete penetration of the lubricant. LAP JOINTS BEIWEEN ALUMINUM ALLOY EXTRUDED SECTIONS. Extruded sections of high-strength materials such as 7075 or 7178 aluminum alloys are more susceptible to intergranular corrosion than are other aluminum alloys. Application and maintenance of chemical processes, sealants, paints, or Par 20 Chap 6 ### Page 19 (OCR) AC 20-64 Page 17 8/1/69 combinations of these protective measures have proven most effective in controlling corrosive attack on these materials. If intergranular corrosion occurs, it is usually found around fastener: r in lap joints. It is evidenced by raised areas or lumps under the paint film, and there have been instances where the attack has progressed to such an extent that there were actually bulges in the faying suriaces. lhese raised areas, lumps, and bulges are due to the accumulation of corrosion products, which take up more volume than did the affected material before it corroded. 25. FLUID ENTRAPMENT AREAS. Design specifications require that aircraft nave drains installed in areas where water may collect. However, li rains are rendered ineffective because they are clogged by debris, sealant, etc., or because the level of the aircraft is changed from that of a normal ground attitude, corrosive agents can collect in a localized area. low-point areas and drains should be inspected frequently to prevent the inception of corrosive attack. Low points of integral fuel tanks are areas where water condensate can collect. This water and condensate is of doubtful purity, and if permitted to stand it can permeate the protective coating of the tank and bring many corrosive agents held in suspension in contact with the vulnerable metallic surfaces. Water condensate should be drained regularly from fuel tanks and the integrity of the tank sealant maintained to prevent corrosion of integral tank surfaces. When considering fluid entrapment areas, one inevitably thinks of aircraft drinking water and wash water systems. Corrosion in these systems is rare because they are fabricated from nonmetallic materials and/or stainless steel. Water stagnation should pose no problems so long as sanitation regulations are heeded. 26. ELECTRONIC PACKAGE COMPARTMENTS. Often the safety of those on board an aircraft rests on the proper function of a little black box. The environment of electronic package compartments is carefully controlled to provide the most ideal conditions that can be achieved. The degree to which such sensitive equipment is exposed to corrosive agents is very small, but even small quantities of moisture and contaminants can adversely affect equipment reliability. Components in these ar as should be inspected for corrosive attack as thoroughly as possib? during routine checks, and advantage should also be taken of nonscheduled component removals for further inspection. 27. CONTROL CABLES. Control cables have preservative coatings which, when intact, prevent corrosive attack. Due to their vital function it is necessary to inspect these cables frequently to ensure that they are adequately protected. During these inspections incipient failures due to other causes also ma be detected. It is recommended that control cables be inspected periodically, then cieaned and treated as necessary before reapplication of the preservatives. Chap 6 Par 24 ### Page 20 (OCR) Page 18 AC 20-64 8/1/69 28. MICROBIOLOGICAL FUEL CONTAMINATION AND CORROSION. Microbiological contamination in turbine fuel is caused by bacteria and fungi which feed on the constituents of the turbine fuel. The result is a sludge, or mat deposit, which has'been found in some aircraft fuel tanks and is often loosely referred to as green slime. However, some deposits have been found in various shades of grey, brown, red, and white. If allowed to develop and grow in the aircraft fuel tanks, microbiological contamination can cause a myriad of problems not the least of which is severe aluminum alloy corrosion in the aircraft integral fuel tanks. Since the subject is large and complex, we recommend Lockheed's "Field Service Digest issue of March-April 1961, Volume 7, Number 5, which is devoted to a full explanation of microbiological contamination, corrosion, treatment and prevention. Likewise, we recommend Lockheed's "Field Service Digest" issue Number 49, dated December 1965, which 1s devoted to general corrosion detection, removal, and control. Par 28 Chap 6 ### Page 21 (OCR) AC 20-64 Page 19 8/1/69 CHAPTER 7. MAINTENANCE INFORMATION 29. I-188 AIRCRAFT MAINTENANCE INFORMATION. The following 18 a listing of significant maintenance difficulties that have been reported by air carriers as mechanical reliabil1ty reports from 1967 and 1968 ADP records. This information may be useful in identifying additional structural inspection problem areas. In all cases, check the corresponding trouble area, left right, top bottom, forward aft, etc. Wing (1) During a routine visual inspection, two cracks were found in the lower right forward front beam cap wing stub fitting, P/N 819229. Each crack was 1 inch long at butt 11ne 65. Another crack 1 inch long was found at the top vertical support I- angle at station 49 below No. 6 wing plank. The aircraft total time was 19,451 flight hours. (2) During a visual inspection, the lower left inboard forward wing-to-box-beam fitting, P/N 819229-1, was found cracked. (3) An 18-1nch spanwise crack progressing outboard from WS 155 at the splice between #3 and #4 upper right wing planks was found during a visual inspection. (4) During a fleet campaign using visual, magnifying glass, dye penetrant, and boroscope inspection methods, the forward top beam cap inboard of No. 2 nacelle at station 165 was found cracked. The cracks were one-eighth inch long and emanated from a screw hole towards the aft end of the beam cap. The aircraft total time was 21,953 flight hours. (5) During maintenance, the left wing truss rib was found cracked at station 167. The total airframe time was 20,378 flight hours. (6) During a visual inspection a 4-inch crack was found in the left rear beam wing stiffener at station 204.7. The aircraft total time was 20,254 flight hours. (7) A routine maintenance inspection revealed a 3/4-inch crack in the left wing forward lower spar cap tang at station 331. The airframe total time was 22,311 flight hours. (8) During a scheduled ultrasonic inspection, the following cracks were found: Chap 7 Par 29 ### Page 22 (OCR) Page 20 AC 20-64 8/1/69 (a) A 36-inch crack was detected at the forward end of No. 2 fuel tank access plate at the forward end of No. 4 wing plank. The crack extended from a point midway in the access plate to a point 36 inches inboard of the access plate. The crack depth varied from six thousandths of an inch to complete fracture over a 2-inch span. (b) The same type crack (as (a) above) was found at No. 3 fuel tank access plate. The crack extended from a point midway in the access plate to a point outboard of the access plate. During a fleet campaign inspection, 1/4-inch cracks were found emanating from the inboard No. 3 nacelle fillet fairing first and third attaching screw holes in No. 1 wing plank. The aircraft total time was 21,563 flight hours. (9) On a routine inspection, the No. 4 sight gage aft mounting screw hole was found with a 1-inch crack in the leap doubler. The airframe total time was 20,708 flight hours. (10) During inspection wing skin cracks were found at two screw holes around fuel gages between No. 3 and No. 4 nacelles. The aircraft total time was 22,287 flight hours. (11) Inspection disclosed a 3-inch crack in the inboard side of the No. 4 fuel tank surge box. The total airframe time was 21,528 flight hours. (12) Maintenance inspection revealed a crack 5 inches aft of the hinge on the access panel at the trailing edge of the wing, 5 feet outboard of No. 4 engine. The aircraft total time was 24,074 flight hours. (13) A 1/2-inch crack was found in the left wing tip upper aft former. Total airframe time was 21,520 flight hours. (14) During a scheduled inspection a 3 1/2-inch crack was found in the left outboard wing-to-nacelle attach plate, P/N 818854-1. The crack occurred 1 5/8 inches from the bottom edge of the plate. Total aircraft time was 21,686 flight hours. (15) Overhaul inspection revealed random cracking of the wing and nacelle skin former webs and stiffeners at the following locations: (a) No. 1 nacelle former flange outboard side station 0.0. Par 29 Chap T ### Page 23 (OCR) AC 20-64 Page 21 8/1/69 No. 2 nacelle former attach angle at lower outboard longeron at aft hinge for No. 1 main landing gear door. (c). No. 3 nacelle attach angle at lower aft edge of No. 3 forward main landing gear door. Total airframe time was 17,700 flight hours. b. Fuselage. Inspection revealed fuselage skin crack on the left side above the aft power receptacle. The airframe total time was 22,603 flight hours. (2) During a fleet campaign, three 1/2-inch skin cracks were found at the lower aft baggage door frame. Cracks occurred at the lower forward frame radius. Total aircraft time was 18,752 flight hours. (3) Inspection disclosed cracked corners above and below the No. 9 left and right emergency exit windows. Crack lengths were 1/8 to 1 1/4 inches. The total airframe time was 17,797 flight hours. During a routine visual inspection, a 2-inch crack was detected in the lower rear corner of the passenger door frame. Total time on the aircraft was 19,733 flight hours. (5) During a visual inspection, a complete fracture of a fuselage web former was found at fuselage station 107.4. The crack was on the right side below the rudder pedals. Total time on the During a walkaround visual inspection, confirmed by dye penetrant inspection, a 2-inch crack was found in a fuselage cap strip at station 118.8. The affected cap strip is on the right side of the nose gear wheel well, below the cockpit flooring. Total time on the aircraft was 22,547 flight hours. (7) An overhaul inspection revealed two fuselage skin cracks. One was found on the left side of the fuselage at the nose wheel well cutout at fuselage station 186. The other crack was found below and to the right of the No. 2 hydraulic pump, between stringers 28 and 29 at fuselage station 738. Time on the aircraft was 17,700 flight hours. (8) During a dye penetrant inspection, a 3/8-inch crack was found in the right rear fuselage-to-wing attaching ring, P/N 801031-102, located just above the floor line. Total time on the aircraft was 20,310 flight hours. Chap 7 Par 29 ### Page 24 (OCR) Page 22 AC 20-64 8/1/69 (9) A crack was found in a pressure web at butt line 40, fuselage station 195. The pressure web affected is located on the right side. Total time on the aircraft was 22,781 flight hours. (10) A 1 1/2-1nch crack was found in a former r1b on the right side at station 550. The crack was located 6 inches below the floor level. Total time on the aircraft was 20,568 flight hours. (11) During overhaul inspection, several fuselage structure cracke were detected as follows: (a) Former flange cracked on left and right sides of fuselage at stringers 30 and 31, station 570.97. (b) Former flange cracked at fuselage station 1150 at stringers 7, 10, and 12 in the tail compartment. (c) Former flange cracked at station 1133 at stringers 70 and 71 in the tail compartment. (d) Former flange cracked at station 768 at stringer 23 located above floor level in the hydraulic compartment. (e) Former flange cracked at upper aft end of forward cargo pit door. (f) Right side cabin floor beam flange cracked at station 652. (g) Right and left side cabin floor beam flange cracked at fuselage station 580 above the forward spar. (12) During structural modification to a cargo configuration, the contractor found the left aft main fuselage frame fitting cracked at station 695. Total time on the aircraft was 19,276 (13) During routine visual inspection, a 3-inch crack was detected across the belt frame at fuselage station 715.50. The crack was on the left side at the floor line. Total time on aircraft was 14,945 flight hours. (14) During inspection, the belt frame on the right side of the fuselage at stringer 19, station 730, was found cracked through. (15) During a scheduled inspection, stringer No. 37 was found cracked at fuselage station 1113. The crack occurred at the forward clip fastener hole. Total time on aircrart was 19,778 flight hours. Par 29 Chap 7 ### Page 25 (OCR) AC 20-64 Page 23 8/1/69 Fuselage stringer No. 49 was found cracked at fuselage station 1117. The crack occurred at the No. 5 fastener on the forward side at the rear pressure bulkhead. Total time on the aircraft was 20,842 flight hours. (17) Fuselage formers were found cracked at the 12 o'clock position at fuselage station 1133, and at the 9 and 2 o'clock positions at fuselage station 1158. Total time on the aircraft was 21,898 flight hours. (18) Fuselage formers were found cracked at 9, 10, 11, 11:30 and 2 o'clock positions at fuselage station 1150, and at the 9 o'clock position at fuselage station 1167. Total time on the aircraft was 21,932 flight hours. (19) Right and left reinforcing angles, P/N 803185-47 and -48, were found cracked at station 1185. One crack was found in the former-to-skin attachment at fuselage station 1167, and another crack was found at station 1133. Total time on the aircraft was 21,151 flight hours. (20) Fuselage former attach tab was found cracked at the 10 o'clock position at fuselage station 1193. Total time on the aircraft was 22,207 flight hours. c. Flight Controls. (1) A 1 1/2-foot fatigue, crack was found at the trailing edge of the wing flap. The crack was located aft of the Mylar strip at the rear of the No. 2 engine. (2) A 9 1/2-inch crack was found on the right horizontal stabilizer front beam web near stabilizer station 29. Total time on the aircraft was 19,853 flight hours. (3) During inspection, the No. 8 balance weight open type arm, P/N 816900-4, on the left elevator was found cracked. Total time on the aircraft was 19,452 flight hours. (4) During main base check, a 1 1/2-inch crack was found in the vertical stabilizer right attach angle at station 1l17. The crack had progressed three-fourths inch forward and aft through the Hi-Lok fastener hole. Total time on the aircraft was 19,437 flight hours. Chap T • Par 29 ### Page 26 (OCR) Page 24 AC 20-64 8/1/69 Pilot reported No. 3 engine vibration indication at and above 220 knots. The vibration was also noticeable by slight buzzing of the power lever on the ground. During cruise, a definite vibration was experienced in the ailerons, elevators, and rudder. The engine vibration was pronounced above 800 degrees engine tailpipe temperature. Inspection of the control surfaces revealed rudder rib damage requiring reinforcement. The rudder was replaced. Total time on the airframe was 15,949 flight hours. d. Main Landing Gears, (1) During overhaul inspection two 3/4-inch cracks were found at the top of the left main landing gear inboard truss rib tabs at wing station 167. The cracks originated from the tab cutouts extending downward and aft toward the truss cap between risers Nos. 16, 17, 18, and 19 of the No. 3 upper wing plank. Total time on the aircraft was 21,734 flight hours. During inspection, the left main landing gear door actuator fitting, P/N 802058-1, was found broken. The mounting bolt was holding the fitting in place. There were 857 landings since the last removal of the door actuator. Total time on the aircraft was 20,268 flight hours. During a dye penetrant inspection, a 1/2-inch crack was detected on the left main landing gear actuator support fitting, P/N 841275-101. The crack was located aft of the outboard hole. Total time on the aircraft was 14,356 flight hours. e • Corrosion. During inspection, exfoliation corrosion was found on the left fuselage longeron, P/N 897596-1, between fuselage stations 474.5 and 484.5. Total time on the aircraft was 20,740 flight hours. During a main base check inspection, corrosion was found in several spots on the aft cargo door fuselage doubler. The bottom edge of the aft cargo door sill is covered by a stainless steel striker plate. Total time on the aircraft was 17,721 flight hours. (3) Heavy corrosion was found on the floor beams at fuselage stations 333 and 371. Total time on the aircraft was 21,520 flight hours. Par 29 Chap T ### Page 27 (OCR) AC 20-64 Page 25 (and 26) 8/1/69 (4) Three separately corroded areas were found on the left upper wing at station 65. The corroded areas were .030 inch deep and 1/2 inch in diameter around the fuselage-fillet-to-wing attach fasteners at wing planks Nos. 1, 6, and 7. Total time on the aircraft was 23,315 flight hours. During scheduled inspection, corrosion was found on the lower wing surface. The corrosion occurred under the fuselage-towing fillet chafe strip at numbers 4, 5, and 6 wing planks. Four spots of corrosion were found measuring .011 inch, .024 inch, .024 inch, and .013 inch. The areas were treated and and filled with epoxy filler before installing repaired doublers. Total time on the aircraft was 21,715 flight hours. (6) Corrosion was found on the lower section of the captain's sliding window frame. Total time on the aircraft was 21,620 flight hours. (7) During inspection, an area of approximately 12 inches by 6 inches on the outside skin at stringer No. 30 and fuselage stations 500 to 549 was found to be corroded beyond limits. Also, two small areas approximately 1 inch square were found corroded at stringer 22, fuselage stations 685 and 690. Total time on the aircraft was 24,649 flight hours. Miscellaneous. (1) An unscheduled landing was made as a precautionary measure due to in-flight cracking of the first officer's windshield. The windshield heat was in the low position. The aircraft was ferried to Buffalo, where the windshield was replaced. Flight time since the last inspection was 17 hours. Total time on the aircraft was 19,644 flight hours. (2) The No. 4 oil cooler flap door was found cracked at the door actuator attach bracket. The crack was approximately one-half inch in length and progressed out of a screw hole toward the door hinge. The oil cooler flap door, P/N 836505-9, was replaced. Total time on the aircraft was 14,286 flight hours. (3) During ground inspection, the No. 4 propeller oil access door, /N 811567-11, was found excessively worn. The wear allowed the upper hinge end of the door to protrude sufficiently to be caught by the propeller blade cuff and be torn free. The aircraft was ferried to its main base, where the propeller cowl panel, P/N 813395-27, was replaced and the propeller cuff repaired. Chap T Par 29 ### Page 28 (OCR) AC 20-64 Appendix 1 8/1/69 Page 1 FIGURE A-1. BASIC DIMENSIONS ELEVATOR HINGE O% CHORI BUTT LINE 357.03 29 FT 1 IN. SUIT FWD FACE FRONT LINE BEAM: 19.11% CHORD • 186.97 42 FT 10 IN. 29 FT 7 IN. • 4 FT 7 5 IN AFT FACE FRONT BEAM: 15% CHORD 7 FT 7 IN. FWD FACE REAR BEAM: 58,56% CHORD & RUDDER HINGE: & AILERON HINGE: 72.5% CHORD 70% CHORD **WATER LINE FUS - 415.0 STA** 571.19 17 FT 4 IN 32 FT .10.5 IN. WATER LINE 150.00 .000 g000 000. 000 10° 5F5 IN 8FT 5 IN - FLOOR 8 FT 1 IN WATER LINE - 5 FT 1 IN. 1 FT 9 IN. 123.94 37 FT O IN 104 FT 8 IN 42.00 STA FUS 177.00 FUS STA 621.00 FUS STA STATIC GROUND 195,000 LBS WITH C.G. @ 25% M. A.C.) **11 FT 4 IN. MAX DIA** - 3 FT 3.7 IN. CLEARANCE 13 FT 6 IN • WING REFERENCE PLANE - &7 IN. **31 FT 2 IN CLEARANCE 99 FT 0 IN. -** ### Page 29 (OCR) AC 20-64 Appendix 2 8/1/69 Page 1 FIGURE B-1. WING STATION DIAGRAM **ACTUATOR TRACK TRACK ACHERIOR** **FLAP STATIONS** **SEE NOTE A** **FLAP STATIONS** 27.8 / 45.8 34-6 TRACK SCREW (TRAILING EDGE STRUCTURE) SEE NOTE A sd.I 94.I E / B21/ TRACK / 143.6 106.9 161.9/186.4 223.1 / 258.2 / TRACK 204.7 TRACK DRIVE SCREW TRACK AILERON STATIONS (174.2) / 251.4 / 263.21 / 331.1 278.1 / 313.7/ | 00|309|65|2|133|675|2017 SEE NOTE B **FUS STA** 694. **FUS STA.** 571.2 15% CHORD (AFT FACE FRONT BEAMY 1291) 1282420 322 397/106/128 413) 159: 73|188/515|526:1541 |556:576 239 197 221 257 293 398 431 **WING STATIONS** WING REFERENCE PLANE 6° 0° **NACELLE** **NACELLE** **CENTER OUTER SECTION AND TIP** SECTION NOTE A. FLAP STATION AND TRAILING EDGE STATION PLANES ARE PERPENDICULAR TO THE WING REAR BEAM. **B. AILERON STATION PLANES ARE PERPENDICULAR** **TO HINGE CENTERLINE AND WING REFERENCE PLANE** ### Page 30 (OCR) Pagendix 2 AC 20-64 Page 8/1/69 FIGURE B-2. WING SKIN SKIN PLANKS AND MATERIAL INDEX FUS STA 694,9 FUS PANEL NO. 4 PANEL NO. 5 PANEL NO. 6 PANEL NO. 7 PANEL NO. 8 PANEL NO. 9 STA PANEL NO. 3 571.2 PANEL NO, 2 STIFF. NO. 61 PANEL NO. 1 STIFF. NO. 57 STIFF. NO. 50 STIFF. NO. 43 STIFF. NO. 36 STIFF. NO. 29 UPPER SURFACE STIFF. NO. 22 STIFF. NO. 15 B. L. 65.0 STIFF. NO. 8 STIFF. NO. 1 NOTE SYMMETRICAL ABOUT B.L. O.O. PANEL NO. 4 PANEL NO. 5 PANEL NO. 6 PANEL NO. 7 PANEL NO. 8 PANEL NO. 9 STIFF. NO. 61 | STIFF. NO. 57 PANEL NO. 3 STIFF. NO. 50 PANEL NO. 2 STIFF. NO. 36 pariara STIFF. NO. 43 PANEL NO. 1 STUFF. NO. 29 LOWER SURFACE B.L. O.0 STIFF. NO. 22 (ROTATED 1800) STIFF. NO. 25 5 TEE - LS4113 (TYP 2 PLACES), SEE 51-3-6, FIGURE 1 (SHEET 2) STIFF. NO. 8 6 ATTACH ANGLE - LS6681, SEE 51-3-6, FIGURE 1 (SHEET 2) B: L. 65.0 STIFF. NO. 1 INTERCOSTAL ASSEMBLY: INTERCOSTAL - LS6258, SEE 51-3-6, PANEL (TYP) - LS7255, SEE 57-2-1, FIGURE 3 FIGURE 1 (SHEET 2) PANEL (TYP) - LS7256, SEE 57-2-1, FIGURE 3 FITTING - LS6300-2-36-557 TUBE - 2024-T3 AL ALLOY SPLICE PLATES - .150 7075-T6 AL ALLOY 4 TEE - LS4929 (TYP 4 PLACES ), SEE • SPLICE PLATE - .190 7075-T6 CLAD 51-3-6, FIGURE 1 I SHEET 2) ### Page 31 (OCR) AC 20-64 Appendix 2 8/1/69 Page 3 FIGURE B-3. WING ACCESS AND INSPECTION PROVISION **FUS STA** - 694. 9 **FUS STA** - 571.2 **BOTTOM VIEW DECAL** **NO INSPECTION OR ACCESS ITEM DENTIFICATION FUEL TANK W106** LOWER TRAILING EDGE 3 FUEL TANK W107 TOP VIEW 4 AILERON TRAILING EDGE 5 FUEL TANK W108 6 AILERON **FLAP TRAILING EDGE** **FILLETS** ENGINE START LINE (RIGHT SIDE ONLY) 10 LEADING EDGE * 11 LEADING EDGE LIGHTS AILERON TIP VIEW B 22 15 14 FUEL PUMP OVERWING FUEL FILLERS NOTE (ROTATED FOR CLARITY ) 16 FUEL TANK W105 A. LEFT SIDE SHOWN. ALL ACCESS OPENINGS 17 FUEL SYSTEM W103 ARE FOR RIGHT AND LEFT SIDES EXCEPT 18 FLAP LEADING EDGE WHERE NOTED. 19 FUEL TANK W102 B. REFER TO 54-0, FIGURE 3 FOR ACCESS TO 20 FUEL TANK W101 WING IN VICINITY OF NACELLES. 21 DRY BAY C. REFER TO 53-0, FIGURES 3 AND 4 FOR 22 CENTER SECTION ACCESS TO WING IN THE CENTER SECTION. * INDICATES A HINGED ACCESS DOOR. ALL OTHERS ARE REMOVABLE ### Page 32 (OCR) AC 20-64 Appendix 3 8/1/69 Page 1 FIGURE C-1. NACELLE STATION DIAGRAM NACELLE STATIONS • 30.4 33.6 54.4 90.6 120.0 53. 1 1-19.1 0.0 24.4 48. 8 77.6 110.0 & THRUST 41.75 1 - 9.5 12.0 | 140.01. | 64.0 104.0/ 130.0 145.0 NAC W.L **0.0 NAC W.L.** -86 NAC STA INBOARD NACELLE - 76. 1 **NACELLE STATIONS** - 9.5 & THRUST -44.2 -31.5 -19.0 0.0 110.0 / 18.0 25.0 70.0 43.96 81.5 91.3 103.2 | 109.0 NAC • W.L. 0.0 **NAC OUTBOARD NACELLE W. L. NAC -&4 STA** - 67.2 P.P. P.P. **STA 81. 1 STA P.P. 49.5 STA STA P.P.** 63.2 29.7 & SIDE COWL HINGES A. POWERPLANT STATIONING IS SAME FOR INBOARD AND OUTBOARD NACELLES. **B. POWERPLANT STATIONS ARE PERPENDICULAR TO THRUST CENTERLINE.** - E THRUST C. NACELLE STATIONS ARE PERPENDICULAR TO NACELLE WATER LINE. **COWLING PROP BLADES P.P. P.P. P.P. P.P. P.P.** **STA STA STA STA STA** 120.6 95 52.0 21.2 0.0 ### Page 33 (OCR) 716.4 8/1/69 AC 20-64 742 754.0 765.7 758.5 < 770.35 768 FIGURE D-1. 789.3- 796.5 129.8 130.4 - 140.1 107.4- 118. 8 - -825 853.5 844 863 837 176. 7- 176.8-5 8 m **872.5 882 875 200 208. 5- - 202.6 FUSELAGE STATIONS DIAGRAM (SERIAL NOS. 1001 AND UP)** 907.8 901 920 ( SEE SHEET 2 FOR LAC SERIALS 2001 AND UP) 2645274 245.5- 255 - 253.4 -236 -272.9 - 958 LAC SERIALS 1001 AND UP 283.5 275.6 - 977 302.5 - - 293 309.3 1005.5 996 VIN 326.3 1024.5 - 1031.4-1031.6 1015 350- 337.5- 354· -333 - 329.3 1037.5 1034 366.5- - 352 -1053 -371 1063.7 - 1072 404. 4397.5 400 -1091 416.5- -407 1122. CANTED CANTED) 1117- 1110 439.7- 426 1133.7 ( CANTED) 454,5- Z447.3 -445 1150. 7( CANTED). $73.5- — 464 1159.2( CANTED ) 1167.71 CANTD- 486.9- 1185.7 ( CANTED) 511.5- 1203. CANTED CANTED) 530.5- -521 1221. CANTED CANTED). 1240. 5( CANTED) 549.5- 559 _565.3 1259( CANTED) 1295.5( CANTED) 1283( CANTED) REFERENCE LINE- TAIL SECTION -571 597 -578 - 613.7 Appendix 4 625.5- 633. 9 637.4 654 Page 1 _673 683. 9 ### Page 34 (OCR) Appendix 4 AC 20-64 Page 2 8/1/69 FIGURE D-2. FUSELAGE STATIONS DIAGRAM (SERIAL NOS. 2001 AND UP) U LEVEL FLOOR W.L. 123.5 NI un 731223 LAC SERIALS 2001 AND UP 1117 **TAIL SECTION** REFERENCE LINE 1005.5- 1024, 5- 1037.5 1063.7- 1122. 3( CANTED) - 1133.7 ( CANTED )- 1150. 7 (CANTED) 1187 4 CANTED 1185. 7( CANTED )- 1203.7( CANTED). 1221. CANTED CANTED) 1240. 5( CANTED)- 1259( CANTED). 1283( CANTED) 1295,5( CANTED) ### Page 35 (OCR) AC 20-64 Appendix 4 8/1/69 Page 3 FIGURE D-3. FUSELAGE CONTOUR COORDINATES FUS STA 42 TO FUS STA 217 - BETWEEN THESE STATIONS THE FUSELAGE IS A FAIRED SECTION. THE CONTOUR SHOULD CONFORM TO THE SURROUNDING STRUCTURE. ONTOUR IS GIVEN: SUBTRACT SKIN THICKNESS (SEE 53-2-1, OBTAIN FRAME, FORMER OR BULKHEAD CONTOUR. 68.00 RAD - W.L. 150 **I SYMMETRICAL FUS STA 901 TO FUS STA 1117 - SEE TABLE ABOUT** **FOR VALUES OF DIMENSIONS AT APPROPRIATE FUSELAGE STATION.** POINT "A" • W. L. 150 POINT "B" POINT "C" POINT "A" POINT IB" POINT 'C" FUS STA Ru B.L. W.L. B.L. W.L. B.L. W.L. 907.8 25 . 13 149.96 64,94 129.83 28.23 88.19 68.00 67.86 68.18 920 1.34 - 96 149.78 66.32 134.96 36.11 92.73 68. 00 67.01 58.85 939 3,75 3.15 149.73 67.76 144.24 45,14 98,09 68,00 64,04 09-94 958 _04 6.57 5,.61 150.20 67.93 152.01 46. 86 103.45 67.96 62.35 70.83 977 .82 9.62 -7.04 150.75 67.18 150.17 44.42 103.63 67.19 60.14 71.47 996 2.26 12.84 7.21 151.58 65.45 140.08 38.75 102.30 65.74 58.50 71. 88 1005.5 3.15 14.50 6.92 152.17 64.21 144. 06 35.23 101.71 64. 85 57.86 72.00 1015 4.06 15.99 6.43 152.94 62.91 143.09 31.76 101.51 63.86 57.33 71.89 1024.5 4.97 17.16 5.87 153.82 61.62 142.96 28.75 101.83 62.78 56.80 71.31 1034 5.88 17.99 5.25 154.81 60.40 143.60 26.07 102.53 61.63 56.28 70.46 1037.5 6.22 18.20 5.00 155.19 59.92 143.80 25.10 102.84 61.18 56.08 70.02 1053 7.70 18.55 3.92 156.97 58.11 146.83 21.58 104.74 59.12 55.14 67.36 1063.7 8.73 18.18 3.19 158.19 56.79 149.15 19.71 106.41 57.59 54.36 64.84 1072 9.52 17.53 2.73 159.08 55.64 150.47 19.21 108.07 56. 37 53.60 62.48 m17 13.83 13.83 163.83 48.96 48.96 48.96 NOTE DATA GIVEN FOR OUTER-SURFACE CONTOUR. SUBTRACT SKIN THICKNESS (SEE 53-2-1, FIGURE 1) TO OBTAIN FRAME, FORMER OR BULKHEAD CONTOUR. **2. BETWEEN FUS STA 1072 AND 1117 THE FUSELAGE IS A FAIRED SECTION.** **THE CONTOUR SHOULD CONFORM TO THE SURROUNDING STRUCTURE.** FUS STA 1117 TO FUS STA 1295 - BETWEEN THESE STATIONS THE FUSELAGE IS A FAIRED SECTION. THE CONTOUR SHOULD CONFORM TO THE SURROUNDING ### Page 36 (OCR) Appendix 4 AC 20-64 Page 4 8/1/69 FIGURE D-4. FUSELAGE CANTED SECTION - W. L.207 -W. L.184 **TAIL SECTION** REFERENCE LINE W. L. 150 1117 1122.3 (CANTED) 1133,7 (CANTED) 1150.7 (CANTED) 1159.2 (CANTED) 1167.7 (CANTED) 1185.7 (CANTED) 1203.7 (CANTED) 1221.7 (CANTED) 1240.5 (CANTED) 1259 (CANTED) - 1283 (CANTED) 1295.5 (CANTED) NOTE **FRAME OR FORMER SEGMENTS** ARE LOCATED APPROXIMATELY FUS STA FRAME OR FORMER REINFORCEMENT AS SHOWN: - (CANTED) 1117 SEE 53-2-3,FIGURE FIGURE I (SHEET 5) 68 - STRINGER NOS 1122.3 (6) THRU (11) - .040 7075-16 CLAD| (8) (9) - LS3255 * 63 (15) (16) (1) (2) 1133.7 (1) THRU (16) -1•032 7075-T6 CLAD FWD FACE - (3) THRU (5), (12) THRU (14) - LS3572-40 (7) THRU (10) - .040 7075-T6 CLAD • 59 (14) 14 1LS3572-4* AFT FACE - (1) THRU (16) - LS6844• 1150.7 SEE SHEET 2 (13) (4) 1159.2 (7) THRU (10) - .040 2024-T4 CLAD. 54 012) 1167.7 SEE SHEET 2 1185.7 SEE SHEET 2 50 1203.7 SEE SHEET 1221.7 SEE SHEET 3 45 (10) (9) 1259 1240.5 .032 2024-T4 CLAD 1283 032 6061-T4 AL ALLOY VIEW LOOKING FORWARD AT A TYPICAL FRAME 1295.5 SEE 53-3-1, FIGURE 1 (SHEET 2) B. PORTION OF FRAME OR FORMER SEGMENT IS INDICATED WHERE NECESSARY AS FOLLOWS: * INNER FLANGE • OUTER FLANGE • WEB C. REFER TO 53-2-3, FIGURE 2 FOR REPAIRS AND NEGLIGIBLE DAMAGE. **IF NOT APPLICABLE, REFER TO 51-3-6, FIGURE 1 (SHEETS 1 AND 2).** ### Page 37 (OCR) AC 20-64 Appendix 5 8/1/69 Page 1 FIGURE E-1. STABILIZERS STATIONS DIAGRAM HORIZONTAL STABILIZER STATIONS 235.5 200.5 218.0 241.3 *ALLIONS NE CANTED 183.0 107.5 134.5 155.5 80 (H.S.S) * 148.0 94.0 80.5 67.0 VERTICAL STABILIZER STATIONS (V.S.S) * - W. L 184 - 00 30° 18.28 1204.0 11 50 FUSELAGE STATIONS (F.S.) 183.5 176.7 106.5 99.0 1072.0 1110.0 1024.0 1091.0 1117.0 1015.0 1053.0 996.0 958.0 920.0 ### Page 38 (OCR) Appendix 5 AC 20-64 Page 2 8/1/69 FIGURE E-2. HORIZONTAL STABILIZER STRINGER IDENTIFICATION STA 28.0 STA STA STA STA STA STA STA (CANTED) STA 53.5 80. 5 107.5 134.5 165.5 200. 5 235.5 AIRPLANE EDGE 40. 0 STA STA STA STA STA STA STA OF ( CANTED) 67.0 94.0 121.0 148. 0 18.0 218. 0 253.0 **REAR FILLET BEAM -** **STRINGER NC. XI** **UPPER SURFACE** **FRONT BLAM** **REAR BEAM 5650 9000000000** LOWER SURFACE FRONT BEAM! FOR REPAIRS: IN AREA MARKED THUS AN. NOTE ITEMS INDICATED THUS * IN CALLOUTS BELOW. IN AREA MARKED THUS . NOTE ITEMS INDICATED THUS * IN CALLOUTS BELOW IN AREAS MARKED THUS EZZA, NOTE ITEMS INDICATED THUS • IN CALLOUTS BELOW. **IN AREAS MARKED THUS B229 SEE SHEET 2** **THIS TYPE REPAIR MAY BE MADE ONLY IN THE LOCATIONS INDICATED ABOVE, ON LEF** AND RIGHT STABILIZERS NOTE: NO REPAIR SHOULD BE ADJACENT TO, NOR DIRECTLY OPPOSITE (IN THE OTHER SURFACE ANOTHER REPAIR OF THIS TYPE. 1 ACCESS DOOR - MAKE FROM .050 7075-T6 CLAD. SHAPE TO SUIT CUT-OUT IN SKIN WITH MINIMUM GAP. ATTACH WITH NASS17-3 SCREWS. 2 DOUBLER - WAKE FROM .050 7075-T6 CLAD. DIMENSIONS NOT SHOWN ARE TO BE TAKEN FROM AIRPLANE. MAKE ACCESS HOLE ENDS SEMI-CIRCULAR. TRIM FLANGE AS SHOWN FOR ANGLE. JOGGLE SIDES ON TO STRINGER FLANGES. 3 ANGLE - MAKE FROM ,040 7075-T6 CLAD, SAME LENGTH AS DOUBLER. TRIM ENDS AS SHOWN IN MAIN VIEW, OR WHERE APPLICABLE, AS IN VIEW "A" 4 FILLER - MAKE FROM .032 7075-T6 CLAD. TRIM ENDS AS SHOWN. 5 SKIN ATTACHMENTS: **ROW O-FOR LENGTH OF DOUBLER, ADD MS20426ADS RIVETS MIDWAY BETWEEN EXISTING RIVETS.** *FOR LENGTH OF DOUBLER, REPLACE EXISTING MS20426ADS RIVETS WTH MS20426DD6 RIVETS. ROWS) AND - IN AREA OF CUT-OUT IN SKIN ADD ANCHOR NUTS (SAME TYPE AS ITEM 7) MIDWAY BETWEEN MS20426AD5 RIVETS RE- PLACED IN EXISTING HOLES ( COUNTERSUNK IN STRINGER OUTSIDE AREA OF CUT-OUT IN SKIN, REPLACE 3 EXISTING RIVETS WITH MS20426DD6 RIVETS. **ROWS AND 1 - MS20426DD6. USE 3 IN EACH ROW, SPACED 1.00 APART EACH** SIDE OF DAMAGE ROWS AND - MS20426DD6. USE 3 IN EACH ROW, SPACED 1.10 APART EACH SIDE OF DAMAGE. **RETAIN ORIGINAL RIVETS. •FOR LENGTH OF DOUBLER ADD MS20426ADS RIVETS MIDWAY BETWEEN EXISTING RIVETS. **STEM ATTACHMENTS - AN470AD5. SPACE 1.00 APART.** ANCHOR NUTS (NIMBER AS REQ) - NAS680A3. POSITION AROUND PERIPHERY OF CUT- CUT-OUT IN S' MAKE ENDS SEMI-CIRCULAR. 9 ADJACENT RIB 10 ORIGINAL SKIN 11 ADJACENT STRINGERS 12 EXISTING STRAP ON ADJACENT STRINGER (WHERE APPLICABLE). ### Page 39 (OCR) 0 8/1/69 AC 20-64 ЛИАНАНАНИ FIGURE E-3. **UPPER SURFACE HORIZONTAL STABILIZER STRINGER IDENTIFICATION** STRINGER NUMBER STA * U. S. GOVERNMENT PRINTING OFFICE: 1980 O - 360-655 STRINGER LOWER SURFACE NUMBER E SYMMETRICAL 1 STRINGER - .071 7075-76 CLAD, SEE 51-3-6, FIGURE 1 (SHEET 1) AND 51-3-7 ABOUT € OF AIRPLANE FIGURE 1 (SHEET 2 2 STRINGER - .050 7075-T6 CLAD, SEE 51-3-6, FIGURE 1 (SHEET 1) AND 51-3-7, FIGURE 1 (SHEET 2) 3 STRINGER - LS6658, SEE FIGURE 2 STRINGER - LS6778, SEE FIGURE 2 NOTE STRINGER - LS6777, SEE FIGURE 2 A. FOR LOCATION OF ALL RIBS, STRINGER - LS6659. SEE FIGURE 2 Appendix 5 SEE 55-0, FIGURE L. STRINGER - LS6796, SEE FIGURE 2 B. LETTERS INDICATE APPLICABLE REPAIR TYPE AS SHOWN ON 8 STIFFENER - .040 2024-4 CLAD, SEE 51-3-6, FIGURE 1 (SHEET 1) STIFFENER - LS6881 (TYPICAL EXCEPT AS SHOWN), SEE 51-3-6, FIGURE 1 Page 3 FIGURE 2. (SHEET 2) 10 STIFFENER - LS3505, SEE 51-3-6. FIGURE 1 (SHEET 2) ### Page 40 (OCR) AC 20-64 CHG 1 10/26/73 Appendix 6 APPENDIX 6. MAINTENANCE NOTES FOR WING STRUCTURAL AREAS 1. INTRODUCTION. These maintenance notes have been compiled to assist L-188 series aircraft owners/operators in maintaining the wing of their airplanes for a long and useful service life. Summarized herein are structural areas of the wing which have shown need for special inspections and/or maintenance during the service history of the L-188 fleet. Types of discrepancies which may be found, the locations, and corrective action measures are listed. The purpose of this information is to acquaint maintenance planning personnel with specific areas of the wing which should be included in an overall wing inspection/ maintenance program. This documentation has been assembled for reference usage and is not intended to replace nor be used in lieu of any maintenance/ inspection material or manual. Detail methods for inspections, maintenanc. and repairs/reinforcements are contained in these existing documents and in the service bulletins referenced herein. Direct assistance for your maintenance/inspection activities can be obtained by contacting the aircraft manufacturer. **2. SERIAL NUMBER (S/N) CODING FOR AIRCRAFT.** 1001, 1002, 1004, thru 1148, 2001 thru 2022. b. 1002, 1004 thru 1043, 1045 thru 1120, 2001 thru 2012. c. 1001, 1002, 1004 thru 1056, 1058, (Right Wing Only), and 1059 thru 1069. 3. LOCKHEED STRUCTURAL SERVICE BULLETIN INDEX• 88/SB-334 - Wing - Wing Leading Edge Attaching Screws - Replacement Of 88/SB-564 - Wing - Inspection of Wing Plank Depressions 88/SB-587 - Wing - No. 4 Wing Plank - Inspection Of 88/SB-591 - Wing - Flap Track Attaching Bolts - Inspection Of 88/SB-593 - Wing - Main Landing Gear Actuating Cylinder Attach Fitting Intercostal - Inspection Of 88/SB-599 - Wing - Main Landing Gear Actuator Support Fittings - Inspection Of 88/ SB - 600 - Wing - Upper Skin Planks - Inspection and Repair Of 88/SB-616 - Wing - Upper & Lower Access Door Lands - Inspection Of 88/SB-619 - Wing - Upper Surface at W.S. 167 and W.S. 209 - Reinforcement 88/SB-620 - Wing - Wing Plank Splices Corrosion and Stress Corrosion Cracks - Inspection and Repair Of 88/SB-625 - Wing - Wing Plank Splices Aft of Main Landing Gear Fulcrum Fittings - Inspection Of 88/SB-628 - Wing - Corrosion of Wing Panels at Centroid Risers - Prevention Of 88/SB-631 - Wing - MLG Ribs - Inspection and Rework Of Par 1 ### Page 41 (OCR) Appendix 6 AC 20-64 CHG 1 Page 2 10/26/73 88/SB-632 - Wing - Upper Surface Cracks at Fastener Holes - Inspection and Repair Of 88/SB-633 - Wing - Outer Wing to Center Wing Attach Fittings - Inspection 88/SB-634 - Wing - Upper Surface Cracks at Trailing Edge - Inspection and Repair - W.S. 143 88/SB-638 - Wing - Wing to Nacelle Attachment Plates - Inspection and Repair Of 88/SB-639 - Wing - Main Landing Gear Rib Caps - Inspection and Rework Of 88/SB-649 - Wing - No. 1 and No. 2 Upper Plank Surface Cracks at Nacelle Fillet Attachment - Inspection and Repair Of 88/SB-652 - Wing - Cracks in No. 3 Upper Wing Panel at W.S. 346 - Preventive and Repair Of 88/SB-653 - Wing - Plank No. 1, Lower Attachment to Spar Cap, W.S. 205-275 - Repair or Reinforcement Of 88/SB-654 - Wing - Rear Beam C11p Inspection - W.S. 179/197 88/SB-655 - Wing - Trailing Edge Rib Panels - Repair and Preventive Reinforcement 88/SB-665 - Wing - Upper Plank No.1, W.S. 168 to W.S. 174, and Upper Forward Spar Cap, W.S. 156 to 178 - Preventive Reinforcement and Repair Of 88/SB-669 - Wing - Repair for Cracks in Wing Lower Surface, Planks Nos. 1 thru 8, W.S. 157 to 219 88/SB-670 - Wing - Crack in Upper Forward Spar Cap Vertical Leg at W.S. 168 - Repair and Preventive Reinforcement 88/SB-675 - Wing - Upper Surface - Repair of Wing Plank Nos. 2 to 4 on Each Side of Inboard Nacelles 88/SB-676 - Wing - Preventive Reinforcement of Upper Planks 1 thru 5 at Inboard Side of Outboard Nacelle 88/SB-678 - Wing - Center Section - Corrosion Repair at B.L. 65 L/R 88/SB-682 - Wing - Upper Surface - Repair for crack in Upper Forward Spar Cap and Web at W.S. 209 88/SB-685 - Wing - Corrosion Around Splice Fasteners, Rework and Repair **4. SERVICE INFORMATION LETTERS (SILS).** a . 88/SIL- 58 Inspection of Wing Planks Under Wing to Fuselage Fillets and Lavatory Drain Valve b. 88/SIL-61 Inspection and Repair of Wing Lower Skin Planks c. 88/SIL-87 General Structures - Sealants for Fuel Sealing, Pressurization Sealing, and Corrosion Protection Par 3 ### Page 42 (OCR) **1C 20-64 CHG 1 10/26/73** **FUEL PROBES** **FUEL TANK FILLER** **ACCESS DOOR** - VERTICAL CRACK - HORIZONTAL CRACK 5 SECTION A-A 3 2 PLANK#1 **FUEL PROBE** ### Page 43 (OCR) **FUEL PUMP ACCESS DOOR PROBES** **FUEL PROBES** **REAR SPAR WS 516 380 359 329 INBD** **ACCESS DOOR** • INBOARD NACELLE **SKATE ANGLES FWD** **ACCESS DOORS WS 380** **UPPER PANEL LH** **LOOKING DOWN INBD** ### Page 44 (OCR) Appendix 6 Page 3 (and 4) **FUEL PUMP ACCESS DOOR-** **FUEL TANK FILLER 6 5** • 4 • 2 209)( 188 65.3. **UPPER PANEL RH** **LOOKING DOWN** **CENTROID RISERS - PLANK** **IDENTIFICATION NUMBER** **FRONT SPAR** **OUTBOARD NACELLE** SKATE ANGLES NOTE: LH AND RH WING **FUEL PROBE IDENTIFICATIONS** **ARE THE SAME** • **WING SECTION** UPPER SURFACE FWD FIGURE F-1. Wing Section Upper Surface ### Page 45 (OCR) **AC 20-64 CHG 1 10/26/73** **LEAP DOUBLER -** ACCESS DOORS WS WS 584 567 550 533 516 499 482 9 DRAI 8 7 5 4 3 2 PLANK #1 WS 55.35 155 ### Page 46 (OCR) **CENTROID RISERS** **LEAP DOUBLER** WS WS W'S 516 499 359 293 **FRONT SPAR** • INBD **DRAIN HOLE** **INBOARD NACELLE FWD** **SKATE ANGLES** - FUEL QUANTITY GAGE OUTI SKAT WS 359 **LOWER PANEL RH** **VIEW LOOKING UP** ### Page 47 (OCR) Appendix 6 Page 5 (and 6) QUANTITY GAGE 7 3 2 →A WS 83 **FUEL OVERFLOW** - PLANK **JPPER PANEL LH IDENTIFICATION -OOKING DOWN HORIZONTAL NUMBER CRACK** **RD NACELLE VERTICAL** **VGLES CRACK** **SECTION A-A** • REAR SPAR TYPICAL PLANK SPLICE CRACK ORIENTATION NOTE: LH AND RH WING **IDENTIFICATIONS** **ARE THE SAME** **WING SECTION** WS LOWER SURFACE 499 50 567 D FWD FIGURE F-2. Wing Section Lower Surface. ### Page 48 (OCR) AC 20-64 CHG 1 Appendix 6 10/26/73 Page 7 FIGURE F-3. SERVICE PROBLEM AREAS Pages 8 through 27 (and 28) refer to various service problem areas and are cross-referenced to the photographs in figures Figures F-4 through F-32. ### Page 49 (OCR) Appendix 6 AC 20-64 CHG 1 Page 8 10/26/73 2 4 5 6 PAGE REF. MAJOR FOR S/N NO. ASSEMBLY ITEM SERVICE HISTORY ILLUST. CODE W-1 Outer Wing Leading Attach Loosening has occurred of the 29 Edge inboard, Screws screws attaching the leading 30 Middle, & Outboard Upper and edge skins to the front spar Sections Lower caps. W-2 Outer Wing Lower No. 1 and 3 Surface depressions have been 31 Surface Planks reported in planks between Wing Stations 478 and 528. W-3 Outer Wing Lower No. 4 Plank Cracks have occurred at the 32 Surface, W.S. 159.6 lower No. 4 wing plank drain hole adjacent to Wing Station 159.6. W-4 Outer Wing Lower Rear Spar Loose and failed flap track 33 Surface | attachment bolts have been found. ### Page 50 (OCR) AC 20-64 CHG 1 Appendix 6 10/26/73 Page 9 7 8 9 10 **RECOMMENDATIONS** **METHOD FREQUENCY TYPE OR METHOD** OF OF OF PREVENTIVE INSP. INSPECTION REPAIR ACTION Visual Inspect at 50 flight hours intervals Remove existing screws and Accomplish and retighten all screws each 300 replace with new type fasteners 88/SB-334. hours until LAC 88/SB-334 is per 88/SB-334. incorporated. Visual Inspect within next 300 hour interval. If depressions exceed limits reinspect each 100 hours until corrective action is taken. Replace H-clips per instructions Same as Column 9. of LAC Service Bulletin 88/SB-564. Externa I Visual Repeat inspections at 1000 hour intervals until permanent repair is incorporated. Interim repairs have special inspection requirements. Visual Inspect within 850 hours and reinspect at 5000 hour intervals. (1) Preventive/temporary Same as Column 9, repair may be effected by Item (2). installing 5/16 Hi-Lok fasteners in drain holes per 88/SB-587C with continued 1000 hr. repeat inspections. (2) Permanent repair/reinforcement can be made by incorporating either SED/63-9015-101 or SED/63-9015-135 shown on Dwg. SED/63-9015B. Replace and/or tighten bolts Same as Column 9. and rework bolt holes per LAC 88/SB-591A. ### Page 51 (OCR) Appendix 6 AC 20-64 CHG 1 Page 10 10/26/73 2 3 4 5 6 PAGE REF. MAJOR FOR S/N NO. ASSEMBLY ITEM SERVICE HISTORY ILLUST. CODE W-5 Outer Wing Lower Wing Plank Cracks have occurred in the 34 Surface, W.S. No. 7 wing plank surface and plank 35 179-197 riser located under the main landing gear actuating cylinder attach fitting angles, P/N 802699. W-6 Outer Wing Lower support Fatigue cracks have occurred at 35 Surface, W.S. 187 Fitting, MLG the aft end of the MLG actuator 36 Actuator support fittings in the radius P/N 800618-1 of the vertical legs. P/N 800618-2 P/N 800618-3 P/N 800618-4 ### Page 52 (OCR) AC 20-64 CHG 1 10/26/73 Appendix 6 7 8 9 10 **RECOMMENDATIONS** **METHOD FREQUENCY TYPE OR METHOD** OF OF OF PREVENTIVE INSP. INSPECTION REPAIR ACTION Visual Within next 2500 flight hours on A/C which have 88/SB-538 Requires incorporated. Otherwise, inspect removal of at 88/SB-538 incorporation, or 801266-1 within next 2500 fIt. hours, door (Dry whichever occurs first. Repair wing plank skin and Same as Column 9. riser cracks per Electra Structural Repair Manual, Section 57-2-1, Fig. 3, Sheets 41 thru 44, LAC Dwg. 841880, and LAC Bay A/C) 88/SB-593C. Repair & 800917 Repeat inspections at 2500 flt. out-of-round holes per LAC Door (Wet hour intervals are recommended. Service Bulletin 88/SB-593C. Bay A/C) Visual, Dye Dye penetrant inspect original Penetrant 800618-3 & -4 fittings within 215 flight hours, Repeat at 425 flt. hrs. Visual dye penetrant inspect aft 4 in. of fittings at each 850 flt. hrs. Visual inspect reworked fittings (radius on aft edge) at each 850 flt. hrs. and dye penetrant inspect at each 1700 flt. hrs. No repeat inspections for new 841275-101, -102 fittings. Install new 800618-3 or Install new fittings, 841275-101 (LH) and P/N 841275. 800618-4 or 841275-102 (RH) support fittings to replace damaged parts per LAC 88/SB-599A. ### Page 53 (OCR) AC 20-64 CHG 1 Appendix 6 Page 12 10/26/73 2 3 4 5 6 PAGE REF. MAJOR FOR S/N NO. ASSEMBLY ITEM SERVICE HISTORY ILLUST. CODE W-7 Outer Wing Upper Wing Planks Cracks up to three inches in 37 Surface under length have occurred under the nacelle inboard and outboard skate skate angles angles of the inboard nacelle. W-8 Outer Wing Upper Fuel Tank Corrosion has been reported on 38 and Lower Surfaces Access lower wing plank access door Door Lands lands due to condensation. ### Page 54 (OCR) AC 20-64 CHG 1 10/26/73 Appendix 6 7 8 9 10 **RECOMMENDATIONS** **METHOD FREQUENCY TYPE OR METHOD** OF OF OF PREVENTIVE INSP. INSPECTION REPAIR ACTION Visual (External, Initial external inspection at 450 Internal) flt. hrs. with repeat at next 450. X-Ray Initial internal inspection at 900 fIt. hrs. with repeat at 3000 hr. intervals. Discontinue inspections after 6000 hrs. if no cracks found. (1) Repair cracks in planks per Same as Column 9, Electra Structural Repair I tem (2). Manual, Section 57-2-1. (2) Install skate angle attachment reinforcement at inbd. and outbd. nacelles per LAC Alert Service Bulletin 88/SB-600A (Ref: LAC Dwg. 841481). Visual Within next 850 flt. hrs. Reinspect at each overhaul period. Remove corrosion per Electra Add protection per Structural Repair Manual 88/SB-606. Refer Section 51-2-14 and add to 88/SB-620G for protective coating per LAC access door gap Service Bulletin 88/SB-606. sealing Repair per LAC Drawing instructions. 841295 when damage exceeds .010 inch depth. NOTE: Contact LAC for repair of damage which exceeds allowable limits of Dwg. 841295. (Refer to 88/SB-620G for access door gap sealing instructions.) ### Page 55 (OCR) Appendix 6 Page 14 AC 20-64 CHG 1 10/26/73 2 3 4 5 6 PAGE REF. MAJOR FOR S/N NO. ASSEMBLY ITEM SERVICE HISTORY ILLUST. CODE W-9 Outer Wing Upper Wing Planks Cracks have occurred in the 39 Surface, W.S. 167 & at MLG Rib wing upper surface in the area 40 W.S. 209 Forgings of the MLG rib forgings. W-10 Center Section Wing, Wing Planks Corrosion and cracks have 30 Outer Wing Upper and occurred at various locations in 37 Lower the upper and lower wing plank 38 Surfaces splices. 41 42 43 W-11 Outer Wing Lower Wing Plank Cracks have occurred in the 44 Surface, W.S. 167 & Nos. 3,4,5, lower wing No. 5 plank of the W.S. 209 & 6. LH inboard MLG fulcrum fitting at the No. 4 and No. 5 splice; also, at a fastener hole in plank No. 6 at approx. W.S. 211. ### Page 56 (OCR) AC 20-64 CHG 1 10/26/73 Appendix 6 7 8 9 10 **RECOMMENDATIONS** **METHOD FREQUENCY TYPE OR METHOD** OF OF OF PREVENTIVE INSP. INSPECTION REPAIR ACTION Visua Initial inspection Install 0.063 inch thick Same as Column 9. and dy e within 700 landings doublers under existing penetrant. with repeat inspections at 1400 external doublers and install Ultrasonic landing intervals. No repeat angle stiffeners on the wing and X-Ray inspections required after internal surface at the Plank may be used incorporation of reinforcements No. 3 & No. 4 splice on A/C in local described in LAC Service Bulletin S/N 1001, 1002, 1004 thru areas. 88/SB-619. 1144, and 2001 thru 2019. Install new external doublers only on A/C S/N 1145 thru 1148 and 2020 thru 2022. Accomplish rework per LAC Service Bulletin 88/SB-619A. Ref. LAC Drawings 841314C, 841315C, 841345, 841346, SED/64-9010, SED/64-9011. V is u al, Repeat inspection intervals As specified in LAC Service Accomplish Ultrasonic based on action taken. Bulletin 88/SB-620G. Service Bulletin 88/SB-620G. Dy e Initial inspection As specified in LAC Service Same as Column 9. Penetrant, within 700 landings Bulletin 88/SB-625D. Ultrasonic with repeat inspections at 1400 landing intervals. Repetitive Seal plank splices under repairs inspections may be discontinued per 88/SB-620G. after incorporation of LAC Service Bulletin 88/SB-625 reinforcements. ### Page 57 (OCR) Appendix 6 AC 20-64 CHG 1 Page 16 10/26/73 2 3 4 5 PAGE REF. MAJOR FOR S/N NO. ASSEMBLY ITEM SERVICE HISTORY ILLUST. CODE W-12 Outer Wing Upper & Centroid Corrosion has occurred in the 32 Lower Surfaces Riser centroid riser cavities under the 45 W.S. 155 Cavities plastic fillers. W.S. 221 W-13 Outer Wing Upper MLG Rib Cracks have occurred in web 34 Surface, W.S. 167 & Web Fillets fillets at rib truss and upper 46 W.S. 209 chord member junctures. W-14 Outer Wing Lower Wing Plank Cracks have occurred at the 47 Surface Nos. 2,3, 4. fastener holes around the fuel 48 W.S. 128 sight gage and fuel overflow W.S. 193 openings on LH and RH lower W.S. 266 wing planks. W-15 Outer Wing Upper Wing Plank Cracks have occurred at screw 39 Surface No. 2 holes in the No. 2 plank at the W.S. 212-230 plank No. 1 and No. 2 splice between W.S. 212 and 230. ### Page 58 (OCR) AC 20-64 CHG 1 10/26/73 Appendix 6 Page I/ 7 8 9 10 **RECOMMENDATIONS** **METHOD FREQUENCY TYPE OR METHOD** OF OF OF PREVENTIVE INSP. INSPECTION REPAIR ACTION Visual At normal maintenance inspection Remove plastic fillers and Install aluminum interval. metallic washers, and remove fillers per any corrosion present in 88/SB-628B. accordance with instructions contained in LAC Drawing 841444. Repair per Dwg. 841443, if required. Install new aluminum fillers as shown on Dwg. 841332, and washers, P/N 841326-101, per LAC Service Bulletin 88/SB-628B. Dye Accomplish within next 1000 Inspect, rework and repair per Per LAC Dwg. P e netrant landings. LAC Service Bulletin 841374 88/SB-630 and Dwg. 841374. : Ref: 88/SB-630. Visual, Dye Initially at 500 hrs. Penetrant Repeat at 1000 hours. No repeat after incorporation of preventive repair. Type A repair where cracks Per LAC Dwg. have not entered risers. Type B 8413718 repairs where cracks extend Ref: 88/SB-631B. thru risers. Ref: LAC Dwg. 841336C and 88/SB-631B. Visual, Dye Initially at 500 hrs. Install appropriate doubler per Install 841364-109 Penetrant Repeat at 1000 hours. LAC Dwg. 841364A. Ref: LAC spacer and Hi-Lok No repeat after incor- 88/SB-632A. fasteners per LAC poration of preventive 88/SB-632A. repair. ### Page 59 (OCR) Appendix 6 AC 20-64 CHG 1 Page 18 10/26/73 2 3 4 5 6 PAGE REF. MAJOR FOR S/N NO. ASSEMBLY ITEM SERVICE HISTORY ILLUST. CODE W-16 Wing Joint-Center Attachment Fatigue cracks have occurred, 49 Sec. to Outer Wing Fittings P/N emanating from the barrel-nut 807352 and access holes of the outer wing P/N 807354 front cap fittings at B.L. 65. W-17 Outer Wing-Trailing Upper Cracks have occurred in the 34 Edge Upper Surtace Plank Nos. trailing edge of Wing Planks W.S. 143 6,7,88. Nos. 6, 7, & 8 at W.S. 143, left and right upper surfaces, and in backup fitting, P/N 803900, for the flap track attachment. W- 18 Outer Wing Lower Wing-to- Cracks have occurred in the 50 Surface Nacelle attachment plate which is 51 W.S. 167 & Attachment located in the inboard nacelle W.S. 209 Plate, on the lower front beam of the P/N 810053-1 left wing assembly. P/N810053-3 P/N810054-1 P/N810054-3 W-19 Outer Wing Upper M a i n Cracks have occurred in the 52 and Lower Surface Landing vertical legs of the MLG rib W.S. 167 & Gear Rib caps. W.S. 209 Caps ### Page 60 (OCR) AC 20-64 CHG 1 10/26/73 Appendix 6 7 8 9 10 **RECOMMENDATIONS** **METHOD FREQUENCY TYPE OR METHOD** OF OF OF PREVENTIVE INSP. INSPECTION REPAIR ACTION Visual, Dye Initial inspection Penetrant within 1100 flight hours for cracks in lower fittings. Within next 3000 flt. hours inspect for cracks and burrs in both upper and lower fittings. Deburr all fittings within the 4100 fIt. hours limit. (1) Replace any cracked Same as Column 9, fittings before further flight, Item (2). with new fittings deburred per LAC 88/SB-633B. (2) Deburr all uncracked fittings having burrs, per LAC 88/SB-633B. Visual Initial inspection within 500 Repair cracks per LAC Dwg. Incorporate landings. No special repeat 841390, or the Electra preventive inspection required after Structural Repair Manual, in reintorcement per incorporation of repair or accordance with LAC Service LAC Dwg. preventive reinforcement. Bulletin 88/SB-634B. 841505. Ref: 88/SB-634B. Visual Inspect within next 700 landings. Replace attachment plate in Install new Repeat inspections every 2000 accordance with LAC attachment plates, landings until plate is replaced. 88/SB-638B. P/N 841656-101 or 841438-101. Internal Inspection recommended within Visual 700 landings and repeat inspections at overhaul periods. Interim action requires inspection at each 120 landings for maximum of 500 landings. Interim action consists of stop Accomplish intent drilling crack in accordance of repair per with LAC Service Bulletin 88/SB-639, 88/SB-639 and Electra drawings Structural Repair Manual. SED/66-9101 and SED/66-9107. Accomplish repair in accordance with 88/SB-639. Ref: Dwgs. SED/66-9101 and SED/66-9107. ### Page 61 (OCR) AC 20-64 CHG 1 Appendix 6 10/26/73 2 4 5 6 PAGE REF. MAJOR FOR S/N NO. ASSEMBLY ITEM SERVICE HISTORY ILLUST. CODE W-20 Outer Wing Upper Wing Planks Cracks have occurred in the No. 29 Surface Nos. 1 & 2 1 Plank at the nacelle fillet 30 attachments at the inboard side 53 of all four nacelles. W-21 Outer Wing Upper Wing Plank Cracks have occurred in No. 3 53 Surface No. 3. upper wing panel along the first W.S. 101-137, row of fasteners adjacent to the 257-275, skate angle of the outboard 275-329, nacelle. and 346 W-22 Outer Wing Lower Wing Plank Cracks have occurred in Plank 54 Surface No. 1 No. 1 from forward edge W.S. 75-153, attachment holes. 223-329, and 385 Outbd. W-23 Outer Wing Upper Rib Attach Cracks have occurred in the rib 46 and Lower Surfaces Clips clips located at the rear beam W.S. 179 P/Nos: forward face upper attachment. W.S. 197 805483-1/-2 805491-1/-2 805482-3/-4 805492-1/-2 ### Page 62 (OCR) AC 20-64 CHG 1 Appendix 6 10/26/73 Page 21 7 8 9 10 **RECOMMENDATIONS** **METHOD FREQUENCY TYPE OR METHOD** OF OF OF PREVENTIVE INSP. INSPECTION REPAIR ACTION Visual, Eddy Initial inspection Current, Dye within 400 flight hours. Penetrant Repeat inspections at intervals not to exceed 1400 flt. hours until preventive reinforcements are incorporated. Type A, Type B, Type C and Type D repair, as appropriate, or Type C repairs in accordance with LAC and reinforcements Service Bulletin 88/SB-649B. or 88/SB-675 reinforcement. Visual Initial inspection within 700 fIt. (1) Repair cracks in wing panel Service Bulletin inspection hrs. unless previously inspected per Dwg. 841507B. 88/SB-652C, for cracks. within 350 hrs. Repeat at normal paragraph 2E. Eddy structural maint. inspection (2) Repair cracks around Ref: Dwg. current or intervals until preventive access doors per Dwg. 841507B. x-ray reinforcement is incorporated. 841655A. optional. Visual Initial inspection within 1000 and D y e flight hours of Service: etin Penetrant issue unless previously inspected Repair in accordance with LAC Service Bulletin Service Bulletin 88/SB-653A 88/SB-653A, and Dwg. No. 841441B Repair | paragraph 2C. (1). within 500 hours. Installation Nos. 841441-175, Installation No. - 176, 177, 178, - 179, -180, 841516-137. Repeat inspections at 4000 hour - 193, -195, and 196. intervals until preventive reinforcement is installed. Visual Dye n aircraft having 10,000 flight Penetrant hours or more, inspect in next 700 hours. Repeat inspection at standard structural inspection interval. (1) Rework existing clips in Same as Column 9, accordance with Dwg. 841509. Item (2). (2) Install replacement clips per Dwg. 841509 in accordance with LAC Service Bulletin 88/SB-654. ### Page 63 (OCR) AC 20-64 CHG 1 Appendix 6 10/26/73 2 3 4 5 6 PAGE REF. MAJOR FOR S/N NO. ASSEMBLY ITEM SERVICE HISTORY ILLUST. CODE W-24 Outer Wing Trailing Trailing Loose fasteners and cracks have 36 Edge, Flap Stations Edge Skin occurred in the wing trailing 125 to 331 Panels, edge skin panels and trailing Trailing edge rib webs and flanges. Edge Ribs. W-25 Outer Wing Upper Upper Cracks emanating from the 37 Surface Plank No. 1 leading edge have occurred in 40 W.S. 156-178 W.S. 168-174 the No. 1 upper planks inboard of the No. 2 and No. 3 nacelles. Upper Forward Cracks have occurred in the aft Spar Cap tang of the upper front spar cap W.S. 156-178 emanating from the first attachment hole in area of the inboard skate angle of the inboard nacelles. ### Page 64 (OCR) AC 20-64 CHG 1 Appendix 6 10/26/73 Page 23 7 8 9 10 **RECOMMENDATIONS** **METHOD FREQUENCY TYPE OR METHOD** OF OF OF PREVENTIVE INSP. INSPECTION REPAIR ACTION Visual (from Conveniently scheduled inspection Electra Structural Repair Service Bulletin access holes period. Manual, Sections 57-4-1, 88/SB-655, to Inter- 51-2-14, and 51-3-9. paragraph 2.C. costal) and Repeat at normal inspection Ref: Dwg. X-ray (trom intervals. 841512 Intercostal to T.E.). Verify cracks using D y e Penetrant (Requires skin removal). Visual, As specified in Per Repair Index Dwg. 841628 Per Drawing X-Ray LAC 88/SB-665D. No. 1 plank: in accordance with Service 841628 in initial inspection within next 50 Bulletin 88/SB-665D: accordance with fIt. hours with repeat inspections 88/SB-665D at intervals not to exceed 625 hours. Spar Cap: 1250 fIt. hour Wing Upper Surface Ref: Dwg. repeat inspection intervals increasing to 2500 flt. hour Dwg. 841580D 841576A intervals after No. 1 plank is 841581B 841577B reinforced or repaired. 841582B 841578A 841579A Special repeat inspections may be Wing Upper Front Spar Cap discontinued for No. 1 plank and spar cap when their respective Dwg. 841623B repairs or reinforcements are 841624B incorporated. ### Page 65 (OCR) Appendix 6 AC 20-64 CHG 1 Page 24 10/26/73 2 3 4 5 6 PAGE REF. MAJOR FOR S/N NO. ASSEMBLY ITEM SERVICE HISTORY ILLUST. CODE W-26 Outer Wing Lower Wing Planks Cracks have occurred in the 35 Surface Nos. 1 thru lower wing planks in the 44 W.S. 157 to 8 vicinity of the Main Landing 54 W.S. 219 Gear ribs at W.S. 167 and 209. 55 W-27 Outer Wing Front Upper Cap Cracks have occurred in upper 50 Spar and Spar spar cap vertical leg and in web 51 W.S. 168 Web at rib attach bolts at W.S. 168. W-28 Outer Wing Upper Wing Planks Cracks have occurred in upper 56 Surface Nos. 2 to 4 wing planks 2, 3, and 4 in skate on each side angle area. of inboard nacelles W-29 Outer Wing Upper Wing Planks Cracks have occurred in upper 30 Surface No. 1 thru wing planks No. 1 thru 5 at W.S. 346 5 at inboard W.S. 346. side of outboard nacelles ### Page 66 (OCR) AC 20-64 CHG 1 10/26/73 Appendix 6 7 8 9 10 **RECOMMENDATIONS** **METHOD FREQUENCY TYPE OR METHOD** OF OF OF PREVENTIVE INSP. INSPECTION REPAIR ACTION Visual Initial inspection within the next Per listed repair installations in Same as Column 9. and Dye 400 hours time in service unless accordance with LAC Service Penetrant previously accomplished. Bulletin 88/SB-669A. LAC Service Bulletin 88/SB-669A for detailed INSTALLATION PLANK instructions. No. 841634 No. 1 & 2 Repeat inspections within 2500 841635 No. 1 fIt. hours or 2500 landings 841636 No. 3, 4,5 whichever comes first. 841642 No. 5&6 841865 MLG Drag Strut Area Visual, Eddy On aircraft having 20,000 flt. Repair in accordance with LAC Service Bulletin current hours or more inspect within 625 Service Bulletin 88/SB-670D, 88/SB-670D, fIt. hours. Repeat inspection at paragraph 2.E. paragraph 2.D. 1250 flt. hour intervals until Ref: Dwg. preventive reinforcement or repair DRAWINGS 841717E which eliminates repeat 841624B inspections is installed. 841738A 841743B 841806B Visual Inspect within 700 flt. hours with Repair in accordance with LAC Same as Column 9 and Dye follow-up inspections at normal Service Bulletin 88/SB-675 and Penetrant structural maintenance inspection Dwg. Nos. 841758 and intervals. 841770A. Visual Normal structural maintenance Preventive reinforcement - See | n s t a | I (accomplish inspection interval, but in no case column 10 for in s tallat i on reinforcements per in conjunc- shall interval exceed that required instructions LAC Service tion with by LAC Service Bulletin Bulletin 88/SB-649 88/SB-649. 88/SB-676. inspection) Ref: Dwg. 841760 ### Page 67 (OCR) AC 20-64 CHG 1 Appendix 6 10/26/73 - 2 3 4 5 6 PAGE REF. MAJOR FOR S/N NO. ASSEMBLY ITEM SERVICE HISTORY ILLUST. CODE W-30 Wing Center Section Upper and Corrosion damage has been 42 B.L. 65 L/R Lower Wing reported in upper and lower 57 Surfaces at wing surfaces at B.L. 65 where B.L. 65 center section joins outer Splice Area sections. W-31 Outer Wing Front Upper cap Cracks have occurred in the 51 Spar W.S. 209 and spar spar web at the MLG rib attach web bolts thru the rib tee, spar web, upper spar cap and nacelle attach fitting. W-32 Outer Wing and Upper and Corrosion damage around plank 43 Center Section B.L. Lower Wing splice fasteners has occurred on O to W.S. 584 Surfaces, both the upper and lower wing B.L. O to surfaces. W.S. 584 ### Page 68 (OCR) AC 20-64 CHG 1 Appendix 6 10/26/73 Page 27 (and 28) 7 8 9 10 **RECOMMENDATIONS** **METHOD FREQUENCY TYPE OR METHOD** OF OF OF PREVENTIVE INSP. INSPECTION REPAIR ACTION Visual Inspect at next periodic with repeat inspections at every major Repair in accordance with LAC Periodic Service Bulletin 88/SB-678A. inspections and structural inspection interval. application of corrosion protection coatings. Visual, Eddy On aircraft having 20,000 hours or Repair in accordance with LAC Service Bulletin current more inspect within 625 flt. Service Bulletin 88/SB-682B, 88/SB - 682B, hours. Repeat inspection at 1250 paragraph 2.F. paragraph 2.E. fIt. hour intervals until preventive Ref: Drawing reinforcement or repair which DRAWINGS 841800C eliminates repeat inspections is 841802 installed. 841804C Visual Normal wing structural maintenance inspection interval, but in no case shall interval exceed Repair in accordance with LAC Periodic Service Bulletin 88/SB-685, inspections and paragraphs 2.C and 2.D. application of that required by LAC Service corrosion Bulletin 88/SB-620. DRAWINGS protection 841867 coatings. 841872 ### Page 69 (OCR) AC 20-64 CHG 1 Appendix 6 10/26/73 Page 29 FIGURE F-4. WING UPPER SURFACE Reference W-1, page 8 W-20, page 20 ### Page 70 (OCR) Appendix 6 AC 20-64 CHG 1 Page 30 10/26/73 88/SB-676 REINFORCEMENT FOR PLANK CRACKS 88:58-620 SPLICE SEALING **NACELLE PILLET DOUBLER** - 36 58-334 LEADING EDGE SCREW TIOHTNESS FIGURE F-5. WING UPPER SURFACE Reference W-1, page 8 W- 10, page 14 W-20, page 20 W-29, page 24 ### Page 71 (OCR) AC 20-64 CHG 1 Appendix 6 10/26/73 Page 31 NI PLANK DEPRESSION Figure E-6. WING LOWER SURFACE Reference W-2, page & ### Page 72 (OCR) AC 20-64 CHG 1 Appendix o 10/26/73 88/SB-628 - CENTROID RISER REMOVE PLASTIC FILLERS, RÉMOVE CORROSION, INSTALL METAL FILLERS 88: 58-587 1/4" DRAIN HOLE PLUGGED NEW HOLE DRILLED PLANK Figure F-7 WING LOWER SURFACE Reference W-3, page 8 W-12, page 16 ### Page 73 (OCR) AC 20-64 CHG 1 Appendix 6 10/26/73 Page 33 88/58-591 INSPECTION OF FLAP TRACK ATTACHMENTS Figure F-8. WING EXTERNAL STRUCTURE Reference W-4, page 8 ### Page 74 (OCR) Appendix 6 AC 20-64 CHG 1 Page 34 10/26/73 WING INTERNAL STRUCTURE 88/5B 630 TYPICAL FILLET AREAS TO BE INSPECTED AND REWORKED W-5, page 10 W-13, page 16 W-17, page 18 MLO RIB-W.S. 167 FIGURE F-9. RIB WS137 Reference 88/SB 634 INSPECT FOR CRACKS AT ATTACHMENTS TO PLANKS 88/58-593 INTERCOSTAL ABOVE P/N 800618 ACTUATOR BITTING ON PLANK 47 **UPPER SURFACE** ### Page 75 (OCR) AC 20-64 CHG 1 Appendix 6 10/26/73 Page 35 WING FLAP FLAP DEL ALA PLANK #7 (REF) INBOARD NACELLE 88/58-593 INSPECT MLG FITTING INTERCOSTAL LOCATED INSIDE BOX BEAM ABOVE FITTING 88/SB-509 INSPECT MLG ACTUATOR CYLINDER ATTACH FITTING 88 SB-669 INSPECTION LOWER SURFACE BETWEEN WS157 AND WS219. FIGURE F-10.WING LOWER SURFACE Reference W-5, page 10 W-6, page 10 W-26, page 24 ### Page 76 (OCR) Appendix 6 AC 20-64 CHG 1 Page 36 10/26/73 NISD STRU © EDGE 88/S8-655 INSPECT FOR CRACKS N SKIN AND RIBS FIGURE F-11. WING UPPER SURFACE Reference W-6, page 10 W- 24, page 22 ### Page 77 (OCR) AC 20-64 CHG 1 Appendix 6 10/26/73 Page 37 88/S8600 CRACKS UNDER SKATE ANGLE AT ATTACHMENTS • 88/58-620 REPAIR 88/S8-665 PREVENTIVE DOUBLER INSTALL NACELLE FILLET ATTACHMENTS WING UPPER SURFACE Reference W-7, page 12 W-10, page 14 W-25, page 22 FIGURE F-12. ### Page 78 (OCR) Appendix 6 Page 38 AC 20-64 CHG 1 10/26/73 88/ S8-620 **PLANK SPLICE SEALING 88/58-606** **FUEL ACCESS DOOR** LAND CORROSION FIGURE F-13. WING UPPER SURFACE Reference W-8, page 12 W- 10, page 14 ### Page 79 (OCR) AC 20-64 CHG 1 Appendix 6 10/26/73 Page 39 50C24i0 DOUBLER INSTALLATION WITH FYTENSION AT PLANK 3 - 4 BECAUSE OF DANT 6 FIGURE F-14. WING UPPER SURFACE Reference W-9, page 14 W- 15, page 16 ### Page 80 (OCR) Appendix 6 AC 20-64 CHG Page 40 10/26/73 00/CR_61G DOUBLER INSTALLATION FILLET REMOVED 885B-665 DOUBLER INSTALLATION (IN PROGRESS) FIGURE F-15. WING UPPER SURFACE tererence W-9, page 14 N- 25, page 22 ### Page 81 (OCR) AC 20-64 CHG. 1 Appendix 6 10/26/73 Page 41 88/52-62 WING PLANK SPLICE REPAIR AND SPLICE GAP SEALING ·8D FIGURE F-16. WING UPPER SURFACE Reference W-10, page 14 ### Page 82 (OCR) Appendix 6 AC 20-64 CHG 1 Page 42 10/26/73 **TILLET ATI** HOLES (REF FIGURE F-17. WING UPPER & LOWER SURFACE Reference W-10, page 14 w-30, page 26 ### Page 83 (OCR) AC 20-64 CHG 1 Appendix 6 10/26/73 Page 43 88/SB-620 88/SB-685 INSPECT FOR CORROSION AROUND FASTENER HEADS AT PLANK SPLICES - FIGURE F-18. WING UPPER & LOWER SURFACE Reference W-10, page 14 W- 32, page 26 ### Page 84 (OCR) Appendix 6 AC 20-64 CHG 1 Page 44 10/26/73 88/SB-625 DOUBLER INSTALLATION LOWER SURFACE INBOARD NACELLE INSPECT THE LOWER SURFACE AT INBOARD NACELLES. IN PARTICULAR LOOK FOR CRACKS AT M. L. G. RIBFEET 98/58-669 FASTENERS PLANK + 5 FIGURE F-19. WING LOWER SURFACE Reference W-11, page 14 W- 26, page 24 ### Page 85 (OCR) AC 20-64 CHG 1 Appendix 6 10/26/73 Page 45 PLANK * 8 LOOK FOR EXTERNAL AND INTERNAL CORROSION AROUND HOLE. INTERNAL EXFOLIATION TYPE CORROSION EXPERIENCED ON WETBAY 88/SB-628 CENTROID RISER CAVITY JACKPAD HOLE AIRCRAFT. PLANK # 7 OUTBO - FIGURE F-20. WING LOWER SURFACE Reference W-12, page 16 ### Page 86 (OCR) Appendix 6 Page 46 AC 20-64 CHG 1 10/26/73 J INBD REAR BEAM CLIP W. S. 17? AND 197 UPPER SURFACE 88/58-654 INSPECTION (TYPICAL) **CRACK TYP** REAR SPAR 88/SB-630 MLG RIB INSPECTION FIGURE F-21. WING INTERNAL STRUCTURE Reference W-13, page 16 W- 23, page 20 ### Page 87 (OCR) AC 20-64 CHG 1 Appendix 6 10/26/73 88/SB-631 CRACKS AT FUEL SIGHT GAGE (TYPICAL MLG DRAG STRUT FITTING DRY BAY AIRCRAFT HAVE COVER INSTALLED INSTEAD OF SIGHT GAGE. SAME POSSIBILI- TY OF CRACK (S) EXIST WS 193 NOTE, PLANK FIGURE F-22. WING LOWER SURFACE Reference W- 14, page 16 ### Page 88 (OCR) Appendix 6 AC 20-64 CHG 1 Page 48 10/26/73 WS 266 SIGHT GAGE 100 TO 1000 GALS **FUEL QUANTITY RANGI PULL OUT UNTIL BRIGHTNESS IN END OF STICK SUDDENLY DARKENS 88/SB-631** **FUEL SIGHT GAGE OPENING** **CRACK IN LEAP DOUBLER** FWD TO REPLACE EXTEND, FULLY BEFORE REMOVAL SLIP TUBE PLANK # 4 OUTBD G 0g0. FIGURE F-23. WING LOWER SURFACE Reference W-14, page 16 ### Page 89 (OCR) AC 20-64 CHG 1 10/26/73 Appendix 6 OUTBO 88/58-633 WING ATTACH FITTING INSPECTION DE-BURR ACCESS HOLES CRACK FIGURE F-24. WING INTERNAL STRUCTURE Reference W-16, page 18 ### Page 90 (OCR) AC 20-64 CHG 1 Appendix 6 10/26/73 FRON 88/SB-638 NACELLE ATTACH, PLATE INSPECTION. PLATES, LOWER SURFACE, INB. AND OUTS. INBOARD NACELLE 167 88/SB-670 REMOVE BOLTS FOR WEB AND SPAR CAP CRACK INSPECTION . FIGURE F-25. WING EXTERNAL STRUCTURE Reference W-18, page 18 W- 27, page 24 ### Page 91 (OCR) AC 20-64 CHG 1 Appendix 6 10/26/73 Page 51 88/SB-670 REMOVE BOLTS FOR WEB AND SPAR CAP CRACK INSPECTION NACELLE ATTACH PLATE INBD 88 / 58-638 NSPECTION 88/5B-682 REMOVE BOLTS WEB AND SPAR FRONT SPAR CK FIGURE F-26. WING EXTERNAL STRUCTURE Reference W-18, page 18 W-27, page 24 W- 31, page 26 ### Page 92 (OCR) AC 20-64 CHG 1 Appendix 6 10/26/73 88/58-639 **MLG RIB FOOT CRACK (TYPICAL CRACK IN RADIUS) 88/SB-503 (REFERENCE)** **MIG RIB FOOT ANGLE REINFORCEMENT** **FACTORY INSTALLED** **MAIN LANDING GEAR RIB** UPPER SURFACE PLANK *4 **DOME RIB W. S. 155** COSTILLA E DOMO FIGURE F-27. WING INTERNAL STRUCTURE Reference W-19, page 18 ### Page 93 (OCR) AC 20-64 CHG 1 Appendix 6 10/26/73 Page 53 88/SB-652 INSPECT THESE AREAS FOR CRACKS FROM RIVET HOLES **OUTBOARD NACELLE PLANT** ATFACHMENTS AT NACELLE FILLET INBOARD NACELLE 88/SB-649 FIGURE F-28. WING UPPER SURFACE Reference W-20, page 20 W- 21, page 21 ### Page 94 (OCR) Appendix 6 AC 20-64 CHG 1 Page 54 10/26/73 INBD NACELLE AREA 88/58-669 PORTION OF INSPECTION AREA 88/S8-653 CRACKS AT ATTACHMENTS THRU THIS AREA PLANK 12 FWD FIGURE F-29. WING LOWER SURFACE Reference W-22, page 20 W- 26, page 24 ### Page 95 (OCR) AC 20-64 CHG 1 10/26/73 Appendix 6 CENTROID RISERS (REF) SKATE ANGLE (REF) 88/58-669 CLEAN AND INSPECT LOWER SURFACE BETWEEN WS 157 AND WS 219 PLANK * 4 PLANK / 3 PLANK 71 FIGURE F-30. WING LOWER SURFACE Reference W-26, page 24 ### Page 96 (OCR) Appendix 6 AC 20-64 CHG 1 Page 56 10/26/73 88/SB-675 INSPECT FOR CRACKS INBOARD AND OUTBOARD OF SKATE ANGLES ACROSS PLANKS 2, 3, AND 4 **SKATE ANGLES INBORAD NACELLE** INBOARD, FIGURE F-31. WING UPPER SURFACE Reference W-28, page 24 ### Page 97 (OCR) AC 20-64 CHG 1 10/26/73 Appendix 6 PLANK 49 FWD PLANK 48 ne 15008 1304 THROWE PLANK 47 • FILLET ATTACH HOLES CORROSION INSPECT BOTH SIDES OF SPLICE FROM PLANK #1 THRU FUSELAGE · 3 FIGURE F-32. WING UPPER & LOWER SURFACE Reference W-30, page 26 --- OpenAirDocs.org is an independent research project of [Contrail Labs](https://contraillabs.com/). It is not affiliated with the FAA or the NTSB. Source documents are U.S. government works in the public domain.