Appendix F BOEING SERVICE BULLETIN 747-53-2307
CODE VARIABLE NUMBER (CONTINUED) ELA RA781-RA782 RB043 EVR RA003-RA004 RA022 RA113 FTL RA026 RA029 RA033 RA632 RA634-RA635 RA741 RA916 RB041 IBE RA585 IRN RA101-RA103 RA112 RA161-RA163 JAL RA521-RA527 RA532-RA534 RA537-RA540 KAL RA216 RA245 RA201 KLM RA671-RA675 RA677 MNR RA701 NAS RA908 NWA RA351-RA360 RA369-RA373 RA601-RA602 ORI RA020 PAA RA002 RA005-RA007 RA009 RA012-RA019 RA027-RA028 RA030-RA032 RA034 RA631 RA633 RA910 RA914 PEX RA559 RA561 RB003-RB005 QAN RA909 RB001-RB002 SAA RB071-RB075 SAB RB101-RB102 TWO RA024 RA201 RA761 RB042 TWA RA104-RA110 RA311 RA581-RA582 RA651-RA652 RD001-RD002 RA114-RA115 RA164 RA309 VAL RA406-RA414 RA903-RA907 UPS RA901-RA902 RA911-RA913 RA915 VAA RA560 WDA RA742 RA762 RB044 Dec 21/89 747-53-2307 Page 6
Appendix F BOEING SERVICE BULLETIN 747-53-2307
CODE VARIABLE NUMBER (CONTINUED)
LISTING BY VARIABLE NUMBER RA002-RA034 RA101-RA115 RA161-RA164 RA201-RA203 RA216-RA217 RA245-RA246 RA251-RA259 RA301-RA312 RA351-RA360 RA369-RA373 RA401-RA414 RA501-RA502 RA521-RA527 RA532-RA540 RA551-RA552 RA559-RA561 RA581-RA582 RA585 RA601-RA602 RA631-RA635 RA651-RA652 RA671-RA677 RA701-RA702 RA721-RA724 RA741-RA743 RA761-RA762 RA781-RA782 RA901-RA916 RB001-RB005 RB041-RB044 RB071-RB075 RB101-RB102 RD001-RD002 RR201
2. Spares Affected None B. Reason This inspection will detect corrosion or cracking in upper body skin longitudinal lap joints caused by disbonding of the cold bond at the lap joint. Continued operation of an airplane that has corrosion or cracking in lap joints could lead to separation of the skin at the lap joint causing rapid decompression of the airplane.
Several operators have reported corrosion, and associated bulging of skin at upper body lap joints on airplanes with 26,733 to 70,000 flight-hours.
One operator reported corrosion of one to three lap joint rivets and bulging of the skin at Stringer 12 near Station 1694 on an airplane with 34,827 flight-hours. This operator also reported cracked and corroded fuselage skin with separation at the lap joint at Stringer 12 L and R at six locations each side from Station 1515 to 1735 and Stringer 4L at Station 1710 on the same airplane with 35,134 flight-hours.
Another operator reported a one-inch skin crack emanating from the lap joint at Stringer 0 near Station 738 on an airplane with 49,800 flight-hours which was suspected to have been caused by corrosion from disbonding at the cold-bonded lap joint (Ref. SILA 747-71). This operator also reported two airplanes with skin corrosion of lap joint at Stringer 4L. On one airplane, with 35,985 flight-hours, this corrosion was found at four locations between Stations 1482 and 1676. On the other airplane, corrosion was found near Stations 1510 and 1615 on an airplane with 36,461 flight-hours.
Also an operator has reported skin corrosion in the lap joint at Stringer 23R near Station 1400 on an airplane with 26,733 flight-hours and skin corrosion with bulging skin involving the lap joint at Stringer 23L between Station 1720 and 1820 There have been numerous additional instances of corrosion reported at the Stringer 23 lap joint.
Dec 21/89 747-53-2307 Page 7
Appendix F BOEING SERVICE BULLETIN 747-53-2307 B. (Continued) This bulletin supersedes that portion of Service Bulletin 747-53-2157 which addresses the upper body skin longitudinal lap joints.
Airplanes previously inspected per Service Bulletin 747-53-2157 require additional inspection of lap joint areas as described herein.
Any lap joint areas repaired per Service Bulletin 747-53-2157 do not require further repair or inspection.
This bulletin does not supersede Service Bulletin 747-53-2253 or Service Bulletin 747-53A2303 which address the upper body skin longitudinal lap joints at Stringer 6 in Section 41.
This service bulletin is the subject of Federal Aviation Administration (FAA) Notice of Proposed Rulemaking 88-NM-1954-AD dated February 9, 1989.
Description Within 1,000 flight-cycles after receipt of this bulletin, conduct a detailed external visual inspection of the upper body longitudinal lap joints at Stringers 23 and above from Station 340 to 520). Visually inspect all lap joints for evidence of corrosion or cracking. Evidence of corrosion includes missing or distressed fasteners, white powder protruding from the lap joint, or bulging or pillowing of the lap joint between fasteners. Repair any corrosion beyond allowable limits or cracking, as specified herein, prior to further flight. Repeat these visual inspections at intervals not to exceed 1,000 flight-cycles for the lap joints in Sections 41 (Station 140-520), 42 (Station 520-1000), and 46 (Station 1480-2360). Repeat the visual inspections at 2,000 flight-cycle intervals for the lap joints in Section 44 (Station 1000-1480).
In lieu of continued reinspections, terminating action may be accomplished.
Terminating action is accomplished when an uncorroded lap joint area is separated between adjacent circumferential splices, adhesive removed, faying surface sealant is applied, and joint is refastened per 747 Structural Repair Manual Subject 53-30-
03. Terminating action in a corroded or cracked lap joint area may be accomplished when the area is repaired per 747 Structural Repair Manual Subject 53-30-03.
It is recommended that this service bulletin be accomplished concurrently with service bulletins 747-53A2265 and 747-53A2279 due to common access.
This service bulletin is the subject of Federal Aviation Administration (FAA) Notice of Proposed Rule Making, FAA Docket Number 88-NM-194-AD. issued February 9, D. Approval This service bulletin has been reviewed by the Federal Aviation Administration (FAA) and the repairs and modifications herein comply with the applicable Federal Aviation Regulations (FAR's) and are FAA approved.
Dec 21/89 747-53-2307 Page 8
Appendix F BOEING SERVICE BULLETIN 747-53-2307 D. (Continued) The deferral of repair described in Accomplishment Instructions, has FAA approval contingent on accomplishment of the inspections at the intervals specified in the Accomplishment Instructions.
Manpower The following breakdown of manpower requirements is suggested as a guide to assist operators in planning and accomplishing this modification. This estimate is for direct labor performed by an experienced crew. It does not include setup, planning, familiarization, cure time, part fabrication, tool acquisition, or lost time.
Factor this estimate as necessary based on your own experience.
Elapsed Time Operation Crew size Man-Hours (Hours) Visual Inspection 152 38 of Lap Joints TOTAL PER AIRPLANE (a) 152 38
(a) Crew size, man-hour and elapsed time shown does not include time for lap joint repair or access to accomplish such repair since it is dependent on the extent of repairs required. It is assumed that operators will not perform terminating action on all lap joint areas at one time. Therefore, crew size, man-hours and elapsed time should be based on operator's experience and on the length and location of the lap joint for which terminating action is accomplished. Accomplishment of terminating action is estimated to be 96 man-hours for each 200-inch length of uncracked and uncorroded lap joint.
Material - Price and Availability None G. Tooling - Price and Availability None H. Weight and Balance No change Dec 21/89 747-53-2307 Tor Page 9
Appendix F BOEING SERVICE BULLETIN 747-53-2307 III. ACCOMPLISHMENT INSTRUCTIONS NOTES: 1. The following paragraphs outline the general accomplishment instructions. The suggested sequence of operations and detailed accomplishment instructions are indicated by circle notes on the figures.
Observe all warning and caution notes in the referenced manual sections.
3. Figure 1 contains the Logic Diagram presentations of the following general accomplishment instructions.
A For all lap joints affected by this bulletin as identifed by Figure 2, perform inspection of the lap splices using the method outlined in the logic diagrams of Figure 1.
Method I Within 1,000 flight-cycles after receipt of this bulletin, perform a detailed external visual inspection of the affected lap splices per Figure 2 circle notes 1 and 3.
Repair any corrosion beyond limits or cracking as specified in Figure 2 circle note 3.
Repeat the detailed external visual inspection at intervals not to exceed 1,000 flight-cycles for the affected lap splices in Section 41, 42, and 46. Repeat the detailed external visual inspection at intervals not to exceed 2,000 flight-cycles in Section 44.
B. In lieu of continued reinspections, terminating action may be accomplished.
Terminating action is accomplished when an uncorroded lap joint area is separated between adjacent circumferential splices, adbesive removed, faying surface sealant is applied, and joint is refastened per 747 Structural Repair Manual Subject 53-30- 03 Figure 9 or 10. Terminating action in a corroded or cracked lap joint area may be accomplished when the area is repaired per 747 Structural Repair Manual Subject 53-30-03. Internal lap joint access to accomplish terminating action can be NOTES: 1. When accomplishing terminating action either with airplane in a specific jacked position or without jacking the airplane, contact Boeing for allowable length of lap joint which may be reworked (specify details of airplane configuration including weight and CG, jacking configuration, and any other work being performed concurrently on the airplane).
2. When accomplishing terminating action on a specific lap joint length, contact Boeing for jacking requirements (specify lap joint being reworked, details of airplane configuration including weight and CG, and any other work being performed concurrently on the airplane›.
Dec 21/89 747-53-2307 Page 12
Appendix F BOEING SERVICE BULLETIN 747-53-2307 When refastening lap joint per Structural Repair Manual Subject 53-30-03 Figure 9 or 10, perform open hole HFEC inspection per 747 Non-Destructive Test Manual D6-7170, Part 6, 53-30-00, Figure 1, 3 or 4 to ensure the lap joint is crack free prior to resizing hole for installation oversize protruding head fasteners.
C. Restore airplane to normal configuration.
Dec 21/89 747-53-2307 Page 13
AC43-204 8/14/97 Appendix F BOEING SERVICE BULLETIN 747-53-2307 Illustration Table of Contents Title Page Figure 1. External Lap Joint Inspection Logic Diagram 12 Figure 2. External Lap Joint Corrosion Inspection and Repair 16 Figure 3. Flight Deck Lap Joint Internal Access 26 Figure 4. Upper Deck Lap Joint Internal Access 30
Figure 5. Main Deck Lap Joint Internal Access32
Dec 21/89 747-53-2307 Page 14
Appendix F BOEING SERVICE BULLETIN 747-53-2307 Inspection Method I Within 1,600 Flight-Cycles After Receipt of this Bulletin Perform the Following 1 Conduct a Detailed External Visual Inspection to Determine if Corrosion or Cracking Exists at Cold-Bonded Longitudinal Body Skin Lap Joints at S-23 and Above From Station 140 to 2360 (Ref Fig. 2) Areas of Cracks No Cracks or Corrosion or Corrosion Conduct Terminating Action on Affected Lap Joints Corrosion but Cracks No Cracks Conduct Terminating Action on Conduct Terminating Action Corroded Lap Joint Between on Remainder of Lap Joint Circumferential Splices Within Within 15 Months 3 30 Months Repeat Inspection of All Nonterminated Lap Joints In Sections 41, 42, 44 and 46 at 1,000 Flight Cycle Intervals FIGURE 1. EXTERNAL LAP JOINT INSPECTION LOGIC DIAGRAM Dec 21/89 747-53-2307 Page 15
AC 43-204 8/14/97 Appendix F BOEING SERVICE BULLETIN 747-53-2307
DISHING OF FASTENER HEAD / EXCESSIVE COUNTERSUNK DEPTH
CRACKS AT
FASTENER SHANK
2. Measuring of pillowing is accomplished by using a suitable straight edge and thickness gage. Minimum length of straight edge should be 4.50 inches. See below:
STRAIGHT EDGE
4.50 -
MIN OUTER SKIN
AT JOINT INBD
INNER SKIN AT JOINT
SKIN PILLOWING
DIMENSION (PILLOWING SHOWN EXAGGERATED FOR CLARITY) FIGURE 1. EXTERNAL LAP JOINT INSPECTION (CONTINUED) Dec 21/89 747-53-2307 Page 16
Appendix F BOEING SERVICE BULLETIN 747-53-2307 Intentionally Left Blank Dec 21/89 747-53-2307 Page 17
AG 43-204 Appendix F 8/14/97 BOEING SERVICE BULLETIN 747-53-2307 STA 520 S-0 STA STA 400 340 STA 260 STA STA 220 S- 14 180 STA 140 A 100000 ENTRY DOOR NO. 1 S-19 0 0 S-23 Indicates area of visual inspections.
SECTION 41
LEFT SIDE FIGURE 2. EXTERNAL LAP JOINT CORROSION INSPECTION Dec 21/89 747-53-2307 Page 18
Appendix F BOLING SERVICE BULLETIN 747-53-2307
OUTER SKIN UP \INNER SKIN DINBOO
TYPICAL LAP JOINT
SECTION A-A FIGURE 2. EXTERNAL LAP JOINT CORROSION INSPECTION (CONTINUED) Dec 21/89 747-53-2307 Page 19