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:
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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.
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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.
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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.
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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.
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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.
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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.
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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. -
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
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)
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
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