# Boeing Alert Service Bulletin 727-53A0124: Boeing Service Bulletin

- Rights: © The Boeing Company. Filed by the FAA in regulations.gov docket FAA-2013-0547; AD 2014-03-21 incorporates this document by reference. Not covered by OpenAirDocs’ CC0 dedication.
- Document: [Boeing Alert Service Bulletin 727-53A0124](https://openairdocs.org/service-documents/boeing/727-53a0124.md)
- Title as filed: Boeing Service Bulletin
- Pages: 39
- PDF: https://openairdocs.org/files/sha256/d9/3b/d93b8adba56666b35f60a0f92ad527e2d9f1a44f80da6d3b4f343b0cb6856b73
- Page: https://openairdocs.org/service-documents/boeing/727-53a0124/file/d93b8adba566

## Text

This text is OCR from a scan. OCR can misread letters and numbers. Each page's text from the PDF; open the PDF at a page with #page=N.

### Page 1 (OCR)

OENG  MASTER COPY
SERVICE BULLETIN  DEC LU 1989
787  SERVICE BULLETIN ENGINEERING  LIBRARY
REVISION TRANSMITTAL SHEET
BOEING COMMERCIAL AIRPLANES  POST OFFICE BOX 3707 SEATTLE, WASHINGTON 98124-2207
Boeing Service Bulletin 727-53A0124
This sheet transmits REVISION 3 dated November 30, 1989
of Service Bulletin 727-53A0124, FUSELAGE - MAIN WHEEL WELL PRESSURE FLOOR
INSPECTION, MODIFICATION AND REPAIR".
NOTE: This revision constitutes a complete reissue.
SUMMARY
This revision  is issued to recommend the modification per this service
bulletin for incorporation on aging 727 airplanes.
additional modification kit to install a 0.100 inch thick doubler between
Body Station (BS) 910 and BS 930 and between Buttock Line (BL) 0 and right
BL 10.  The incorporation threshold for this service bulletin is shown in
the Description and Accomplishment Instructions.
As a result of the FAA-sponsored Aging Fleet Conference, a 727 Structures
Working Group with Airline and Boeing members and FAA observers was formed
to review structural service bulletin modifications and recommend selected
bulletins for incorporation on aging airplanes. Based on a structural
review of the 727 airplane, the Structures Working Group has determined
that modification per this service bulletin, at or before the indicated
threshold, should be accomplished to support the continued structural
integrity of aging 727 airplanes.
Airplane effectivity is expanded, to include all 727 airplanes, and updated
to reflect current airplane ownership.
Airplanes modified per previous releases of this service bulletin require
inspection until modified to add the additional doubler between BS 910 and
BS 930 and between BL O and right BL 10.
The original issue of this bulletin was issued, as an Alert Service
Bulletin, therefore the "A", is added to the bulletin number.
This service bulletin is rewritten to comply with current service bulletin
format and therefore revision bars have been omitted because of the
extensive rewrite.
REVISION HISTORY
Original Issue:  May 3, 1974
Revision 1:  September 27, 1974
Revision 2:  May 2, 1975
Revision 3:  November 30, 1989

### Page 2 (OCR)

BOEING
SERVICE BULLETIN
_ SUMMARY
BOEING COMMERCIAL AIRPLANES POST OFFICE BOX 3707 SEATTLE, WASHINGTON 98124-2207
SUBJECT: FUSELAGE - MAIN WHEEL WELL  ATA: 5314  NUMBER: 727-53A0124
PRESSURE FLOOR INSPECTION,  DATE: May 3, 1974
MODIFICATION AND REPAIR  REVISION 3: November 30, 1989
BACKGROUND
Based on a structural review of the
727 airplane, incorporation of the
modification per this service bulletin
is recommended on aging airplanes.
Three operators reported cracks from
25 to 48 inches long in the Main
Landing Gear (MLG) wheel well pressure
floor.  resulting  in
depressurization.
operators reported 67 airplanes with
cracks up to two inches long located
in the reinforcing beads between Body
Station (BS) 910 and BS 940 on both
sides of the airplane between Buttock
Line (BL) 10 and BL 50. The airplanes
had accumulated between 12,600  and
43,300 flight cycles and 18,000  and
51,600 flight hours.
Since Revision 2 five operators
reported five airplanes with cracks
out of the area covered by  the
modification of the service bulletin.
The cracks were located  in  the
reinforcing beads between BS 910 and
BS 930 and between BL 0 and right BL
The airplanes had accumulated
between 18,200 and 42,100 flight
cycles and 21,300 and 39,900 flight
hours.
Continued operation with undetected
cracks could result in loss of cabin
pressure.  The cracks have been
attributed to fatigue.
This service bulletin is the subject
of Federal Aviation Administration
(FAA)  Airworthiness  Directive
77-13-15, Amendment 39-2944.
ACTION  (PRR 23792)
As recommended by the 727 Aging Fleet
Structures Working Group, accomplish
modification per the Accomplishment
Instructions  at  or  before  the
accumulation of 60,000 flight cycles.
Inspect pressure floor reinforcing
beads adjacent to BS 910 floor beam of
airplanes that have accumulated 15,000
flights at maintenance intervals as
described in the Description and
Accomplishment  Instructions until
accomplishing preventive modification
or repair per this service bulletin.
Group 2 and 3 airplanes and airplanes
previously modified require inspection
of unmodified areas at 2000 flight
cycles intervals until accomplishing
preventive modification or repair per
this service bulletin.
If cracks are found within specified
limits, accomplish repair per this
service bulletin. If cracks exceed
specified limits, contact Boeing.
If no cracks are found, accomplish the
preventive modification per this
service bulletin or repeat inspection
at  specified  intervals  until
accomplishing preventive modification
or repair per this service bulletin.
EFFECTIVITY
All 727 airplanes in three groups.
Group 1 - Line numbers 1 through 1102.
Group 2 - Line numbers 1103 through
1477.
Group 3 - Line numbers 1478 through
1832.
Summary Page 1 of 2

### Page 3 (OCR)

BOING SERVICE BULLETIN 727-53A0124
MANPOWER  MATERIAL INFORMATION
Elapsed
Kit  Delivery  Price
Total  Time
Applicability  Man-Hours  (Hours)  65-97861-6**  22 weeks  $2906.00
65-89360-128  12-08-89  $ 283.00
Inspection  2  2
Modification  222  35  ** Additional kits,  suitable  for
Repair  *  repair are  available.  See
* Time is subject to extent of repair.  Paragraph II.A.1.
See Paragraph I.F for applicable terms
and conditions.
STA
950
STA  910  / SEE DETAIL I
STA
870
UP
FWDÕ  LEFT SIDE MAIN WHEEL WELL
• +1
-_STA
910
TYPICAL
CRACK
STA
920
DETAIL I
(PLAN VIEW)
May 3/74
REV. 3:  Nov 30/89  Summary Page 2 of 2

### Page 4 (OCR)

BOEING COMMERCIAL AIRPLANES  BOEING  POST OFFICE BOX 3707  SEATTLE, WASHINGTON 98124-2207
SERVICE BULLETIN
727
ATA SYSTEM: 5314  NUMBER: 727-53A0124  DATE: May 3, 1974
REVISION 3: November 30, 1989
SUBJECT: FUSELAGE - MAIN WHEEL WELL PRESSURE FLOOR INSPECTION,
MODIFICATION AND REPAIR
I.  PLANNING INFORMATION
A. Effectivity
1. Airplanes Affected
See Service Bulletin Index Part 3 for cross reference of Variable
Number to Airplane Serial Number.
This change is applicable to airplanes listed below in accordance
with PRR 23792.
LISTING BY CUSTOMER CODE AND VARIABLE NUMBER
CODE GROUP VARIABLE NUMBER
AAL  E0301-E0303 E0305-E0309 E0311-E0326 E0328-E0330
E0332  E0334  E0336-E0339 E0345
E0348-E0349 E3075  E3519-E3520 QA014
QA101-QA141 QA854  QA856 -QA869
2  QA142 -QA187
QA188-QA199 QB801-QB810
AAT  1  E3029  E3032-E3033 E3062  E3286-E3289
ACE  1  E0130  E3148  E3651
ACN  1  QD205
2  QD206-QD212 QD215-QD217
3  QD218-QD239
AFA  1  QA351-QA352  QA551-QA556 QA559-QA570
3  QD761-QD769  QD781-QD782
May 3/74  727-53A0124
REV. 3:  Nov 30/89  Page 1 of 35

### Page 5 (OCR)

BOLING SERVICE BULLE IN 727-53A0124
CODE GROUP  VARIABLE NUMBER (CONTINUED)
AFG  1  E5410  E5424
ALG  1  QA574-QA576
2  QB451-QB453
QB454-QB458
AMA  1  E3681
AMJ  1  E0104  E0310  E0342  E3028
E3145  E3341  E5161  E5403
ANA  QA040
QA044-QA046
ANC  1  E0133
ANS  1  E0119
3  QD040
ARG  2  QD601 -QD603
3  QD450  200-0900
ASA  1  E3401  INSER  E5058  E5142
QA902  9060-5060
2  QA378  QA894-QA895 QD902  QD904- QD905
25600-I560Ò ZE600-1E600
3  QB619  27980  QB624  QB626 -QB628
QD555  QD909  QD953-QD954
AUS  1  QD001-QD004
2  QD007 -QD009
3  QD010-QDO12
AVG  2  QD191-QD192
3  QD518
AVI  1  E3036  E3141-E3143 E3204
E3221-E3224 E3402  E3406  E3412
E5451  QA572  QB031
2  QD553-QD554
3  QD581-QD583 QD991-QD992
AVN  1  E0034-E0036 E3024  E3072  E3244
E3246  E3511  QA036
QA039  QA041-QA043 QA853  QD121
3  QD474-QD475
AVO  E3038
May 3/14  727 - 53A0124
REV. 3:  Nov 30/89

### Page 6 (OCR)

BOEING SERVICE BULLL.IN 727-5. A0124
CODE GROUP  VARIABLE NUMBER (CONTINUED)
AVT  1  E3654  E5225  E5405
BHR  QD451
1  QB032-QB033
BLA  1  E3005
BLG  1  E5351-E5352
BNF  1  QD031 -QD032
2  QA897-QA899 QB601-QB615
3  QB616-QB617
BNR  1  E3509
BRS  E3065  E5112  E5141  E5481-E5483
CAF  1  E3506  E3512  E5409  E5435
CAL  1  E0038-E0042 E0202  E0205  E3001
E3241  E3245  E3247  E3253
E5201  E5455  QA019-QA021 QA301-QA306
QA308 -QA314  QA325-QA340
2  QA341-QA344  QA890 -QA893 QA896
3  QA345-QA349  QB901-QB904
CAY  3  QB625
CKE  E0304  E5050
CMA  1  QB034  QB036-QB040 QD085- QD088
2  QB041-QB046 QD444
3  QB047 -QB049  QB051-QB058 QB060-QB064 QD571-QD572
CMI  1  E3202  E3409  E3411  E3415-E3418
E5032  E5042-E5043 E5045
CMR  2  QD410
CRU  1  E3071  E3344-E3345 E3781-E3783
DAL  1  QA073-QA079 QA081-QA092 QA096-QA097 QA907
QA909 -QA917
2  QA098-QA099 QA919-QA926 QA929-QA933 QB501-QB552
3  QA939-QA946 QA949  QB553-QB575
DAN  E3146  E3149  QB035  QB114
QDOO5  QD033  QD123
QD903  QLO04-QLOO5 QL031-QL032
May 3/14  REV. 3:  Nov 30/89  127 - 5340124

### Page 7 (OCR)

BOEING SERVICE BULLETIN 727-53A0124
CODE GROUP  VARIABLE NUMBER (CONTINUED)
DHL  1  E0030  E0124  E3622  E5046-E5047
E5274  E5382  E5402
DLH  1  2B105-QB110 QB115-QB119 QB301-QB30!
2  OB310-QB316 QB351-QB352
DNV  1  E0351
DOC  1  E3206
DOM  1  E3755  E5404
2  QD351
DON  1  E3014
EAD  QB065  QD452
EAL  QA601-QA605  QA607 -QA620 QA622  QA624
QA627 -QA643
2  QA644-QA658
3  QA659-QA684 QA686-QA688
EKO  1  E5418
ESM  3  QD908
ETH  3  QD661-QD663
EUR  1  QA573  QA855
EVR  E3101  E3151-E3152 E3275-E3276 E3652
E5104-E5105  E5108  E5273  E5277
E5281  E5426
FAA  1  E0201  E5241
FAM  1  E5353
FBT  1  E3704
FCT  1  QA901  QA904
FED  1  E0120  E0122-E0123 E0125-E0129 E0131-E0132
E0134-E0138  E3257-E3261 E3266-E3267 E3273-E3274
E3277  E3283  E3290  E5048-E5049
E5052-E5054 E5056-E5057 E5059-E5063 E5067
E5101-E5102 E5163-E5164 E5221-E5224 E5226-E5240
E5242  E5408  E5420  E5454
QD035-QD036 QD201-QD204
2  QD037-QD039 QD213-QD214
3  QD041-QD042 QL501-QL515
May 3/74  727-53A0124
REV. 3:  Nov 30/89  4

### Page 8 (OCR)

BOEING SERVICE BULLETIN 727-53A0124
CODE GROUP  VARIABLE NUMBER (CONTINUED)
FMR  1  E3346
FRB  E3655
FTL  1  E0331  E0333  E0335  E0340-E0341
E0343-E0344  E0346-E0347 E3070  E3073-E3074
E3076  E3577
FUN  E3419
GEO  1  E0216
GLE  1  E3144
1  E0101
GTR  1  E3701-E3703 QA038  QA908  QA918
HAP  E3114  E3452
3  QD971-QD972
HAV  1  E3026  E3116
HEM  E3077
HTV  1  E3176
IAL  1  QA002  QA359
IBE  QB121-QB145 QB147-QB149
2  QB151-QB153
3  QB155-QB158
ICC  E3064  E3069
ICE  1  E5417  QDO06
3  QD791
INI  1  E3150
IRN  1  E0204  E3118  E3472-E3473 QD101-QD103
QD104-QD105
IRQ  2  QD421-QD423
3  QD424-QD426
JAM  2  QD281-QD284
JAT  1  QD142 -QD143
2  QD144-QD145
3  QD146-QD149
May 3/74  727-53A0124
REV. 3:  Nov 30/89

### Page 9 (OCR)

BOEING SERVICE BULLETIN 727-53A0124
CODE GROUP  VARIABLE NUMBER (CONTINUED)
JPA  1  E0206
JTA  1  E0213  E3407
JTE  1  E0418  E0420- E0422 E3117  E3201
E3205  E3347-E3348 E3350
KAB  1  E0103  E0107
KAL  1  QA015  QA022  QA024-QA025 QA033-QA035
QA037
KBA  1  E3574
KEL  E5001  E5428
KEY  E0029  E0033  E3027  E3243
E3250-E3252 E3571
KLA  E3604
KUW  QD801-QD804
LAA  1  QA316
2  QA317-QA324 QB651
LAB  E3102  E3522  E5421
2  QD161-QD163
LAC  3  QD701-QD702 QD907
LDE  1  E0032  E3103  E3517  E3573
E5051  E5115
LIL  QD973
INA  2  QD446
MAA  1  E3030
MEZ  1  E0211
2  QD906
MGM  1  E3504-E3505 E3510
MME  1  E0209
MXA  1  E3171-E3172 E3174-E3175 E3553
MXG  1  E3035  E3037
May 3/74  727-5340126
REV. 3: Nov 30/89

### Page 10 (OCR)

LOEING SERVICE BULLETIN 727-53A0124
CODE GROUP  VARIABLE NUMBER (CONTINUED)
NAU  1  E5501
NGA  3  QLO81
NMB  1  E3242
NOB  1  QA557 -QA558
NOM  1  E5279
NWA  E3021-E3023  E3025  E3031  E3034
E3039-E3040 E3173  QA701-QA703 QA705-QA706
QA708-QA720 QA722-QA723
QA725-QA745 QD441-QD443 QD445  QD447
QA746-QA753 QD448-QD449 QD453  QD711-QD717
OCP  1  E3004
OLY  1  QA001  QA801-QA805
OMA  E0210
ORI  1  E3003  E5002  E5004  E5006
E5031  E5036-E5037 E5039  E5041
E5044  E5280  E5381  E5401
E5411  E5423  E5433  E5502
PAA  1  QA003  QA057-QA058 QA201-QA207 QA209-QA214
QA216-QA225 QA366  QA369-QA371 QA704
QA707  QA721  QA851-QA852 QB001-QB002
QB101 -QB104
3  QD691-QD692 QD821-QD828
PAF  1  E3203
PAN  1  E3115
PCT  1  E3507  QD401
PER  1  E3503  E3621  E5278
PEX  1  QA059-QA072 QA870-QA877
2  QA878-QA889 QD501-QD510
3  QD512-QD517
PIE  1  QA005 -QA009  QA023  QA026-QA032 QA051-QA056
QA358  QA360-QA365 QA367-QA368
2  QA372-QA373 QA928
3  QA374-QA376
REV. 3: Nov 30/89  May 3/74  727 - 5340124

### Page 11 (OCR)

BOEING SERVICE BULLETIN 727-53A0124
CODE GROUP  VARIABLE NUMBER (CONTINUED)
PJE  1  E0413
QAT  2  QD403
RAM  1  QA577 -QA579
2  QA581 -QA584
3  QA585
RBA  1  E0212
3  QD407
RBH  QE002
RGI  1  E3285
RJA  3  QD124- QD126
RNA  1  E3784  E5419
RNF  1  E3420
RNZ  1  E5065  E5068
RVV  1  E5035  E5040
RYN  1  E5003  E5005  E5007-E5011 E5413
E5415
SAE  1  E0414  E3576
SAH  1  E3113
SAK  1  E0208  E3451
SAN  1  E3684
SCA  3  QB629
SEN  2  QD402
SIG  1  E0207
SKL  E3421
STR  QLO01-QL003
QD164  QD427  QD684-QD685 QL006-QL008
SYR  2  QD471-QD473
TAM  E3513  E3516  E3682
3  QD741
May 3/74  727-5340124
REV. 3:  Nov 30/89

### Page 12 (OCR)

BOLING SERVICE BULLETIN 727-53A0124
CODE GROUP  VARIABLE NUMBER (CONTINUED)
TAP  1  QA093-QA095  QD302
QD303-QD304
TBL  1  E3013  E3501  E3653
THY  1  QD321-QD322 QD324
2  QD325  QD511
QD327 -QD330
TMI  1  E3410
TNN  1  ES114
TOS  1  E3011-E3012 E3508  QA004  QA903
TOU  1  E3002
TRD  1  E3284
TRI  QD910
TSI  E0106  E0116  E0121  E0140
E3342-E3343 E3349  QA010-QA012 QA017 -QA018
QA353-QA355 QA357  QA606  QA623
QA625-QA626
TUN  1  QA571  QB401
2  QB402-QB407
TWA  E0401-E0402 E0404-E0408 E0410  E0412
E0416-E0417 E0419  E0423  QA501-QA527
QA529-QA537 QB201-QB203
2  QB204-QB210
3  QB211-QB220
UAL  1  E0001  E0003  E0005-E0028 E3254-E3256
E3262-E3265 E3268-E3272 E3278-E3282 QA401-QA428
2  QA429 -QA474
3  QA475-QA499 QB701-QB705
ULL  1  E3523
U05  1  E0203
U06  1  E3061  E3063  E3066-E3067
UPS  E5033-E5034 E5038  E5106-E5107 E5109-E5111
E5113  E5116  E5162  E5243-E5245
E5251-E5252 E5271  E5275-E5276 E5301-E5306
E5422  E5427  E5429
QA927  QA934-QA935 QD551-QD552
QA936 -QA938
May 3/74  REV. 3: Nov 30/89  727 - 53A0124

### Page 13 (OCR)

BOEING SERVICE BULLETIN 727-53A0124
CODE GROUP  VARIABLE NUMBER (CONTINUED)
USA  3  QB066-QB068 QB618  QB620-QB621 QB623
QD681-QD683
USV  1  E0215  E3059
VAC  1  E3683
VAR  1  E3572  E3575  Е3751-E3754 E5272
E5406-E5407 E5412
VSP  3  QD556-QD557
VTC  1  E3006
WEF  1  E0350
WST  3  QE001
WWC  1  E3601-E3603
YEM  QD621-QD624 QD641
ZAR  1  E0214
LISTING BY VARIABLE NUMBER
GROUP 1
E0001-E0042 E0101-E0140  E0201- E0216  E0301- E0351  E0401-E0423
E3001-E3006 E3011-E3014 E3021-E3040 E3059  E3061-E3077
E3101-E3103  E3111-E3118 E3141-E3152  E3171-E3177  E3201-E3206
E3221-E3224  E3241-E3290 Е3341-E3350  E3401-E3421  E3451-E3452
E3471-E3474  E3501-E3513 E3516-E3523  E3551-E3553  E3571-E3578
E3601-E3604  E3621-E3622  E3651-E3655 E3677  E3681-E3684
E3701-E3704  E3751-E3755  E3781-E3784 E5001-E5011  E5031-E5068
E5101-E5116  E5141-E5143  E5161-E5164 E5201-E5203  E5221-E5245
E5251-E5252  E5271-E5281  E5301-E5306 E5351-E5353  E5381-E5382
E5401-E5424 E5426-E5429  E5433  E5435  E5451-E5455
E5481-E5483 E5501-E5502 QA001-QA043 QA051-QA097 QA101-QA141
QA201-QA225 QA301-QA316  QA325-QA340 QA351-QA371 QA401-QA428
QA501-QA537 QA551-QA579  QA601-QA643 QA701-QA724 QA801-QA805
QA851-QA877 QA901-QA918  QB001-QB002 QB031-QB040 QB101-QB110
QB114-QB119 QB121-QB149 QB201-QB203 QB301-QB309 QB401
QD001-QD006 QD031-QD036  QD085-QD088 QD101-QD103 QD121-QD123
QD141-QD143 QD201-QD205  QD301-QD302 QD321-QD324 QD401
QLO01-QLO03
May 3/74  727-53A0124
REV. 3: Nov 30,89  10

### Page 14 (OCR)

BOEING SERVICE BULLETIN 727-53.10124
LISTING BY VARIABLE NUMBER (CONTINUED)
GROUP 2
QA044-QA046 QA098-QA099 QA142-QA187 QA317-QA324 QA341-QA344
QA372-QA373 QA378  QA429-QA474 QA581-QA584 QA644-QA658
QA725-QA745 QA878-QA899 QA919-QA935 QB041-QB046 QB151-QB153
QB204-QB210 QB310-QB316 QB351-QB352 QB402-QB407 QB451-QB453
QB501-QB552 QB601-QB615 QB651  QD007-QD009 QD037-QD039
QD104-QD105 QD144-QD145 QD161-QD163 QD191-QD192 QD206-QD217
QD281-QD284 QD325-QD326 QD351  QD402-QD403 QD410
QD421-QD423 QD441-QD447 QD471-QD473 QD501-QD511 QD551-QD554
QD601-QD603 QD901-QD906 QD931-QD932 QD951-QD952 QL004-QL005
QL031-QL032
GROUP 3
QA188-QA199 QA345-QA349 QA374-QA376 QA475-QA499 QA585
QA659-QA688 QA746-QA753  QA936-QA946 QA949  QB047-QB049
QB051-QB068 QB154-QB158  QB211-QB220  QB454-QB458 QB553-QB575
QB616-QB629 QB701-QB705  QB801-QB810 QB901-QB904 QD010-QD012
QD040-QD046  QD124-QD127  QD146-QD149 QD164  QD218 -QD239
QD303 -QD305  QD327-QD330  QD424-QD427 QD448-QD453
QD474-QD475  QD512 -QD518  QD555-QD558 QD571-QD572 QD581-QD583
QD604-QD607  QD621-QD624  QD661-QD663 QD681-QD685
QD691-QD692  QD701-QD702  QD711-QD717 QD741  QD761-QD769
QD781-QD782  QD791  QD801-QD804 QD821-QD828 QD907-QD910
QD953-QD954  QD971-QD973 QD991-QD992 QE001-QE002 QL006-QL008
QLO81  QL501-QL515
2.  Spares Affected
None
May 3/74  727-53A0124
REV. 3: Nov 30/89  11

### Page 15 (OCR)

BOEING SERVICE BULLETIN 727-53A0124
B. Reason
As a result of the FAA-sponsored Aging Fleet Conference, a 727
Structures Working Group with Airline and Boeing members and FAA
observers  was formed to review structural  service bulletin
modifications and recommend selected bulletins for incorporation on
aging airplanes.  This service bulletin modification has
recommended for incorporation on aging 727 airplanes.
Incorporation of the preventive modification described in this
bulletin will reduce the possibility of cracks in the nain gear wheel
well pressure floor adjacent to the floor beams at Bod; Stations (BS)
900, 910 and 920.  If cracks occur and progress undetected, they could
result in rapid loss of cabin pressurization.
Three operators reported cracks from 25 to 48 inches long in the Main
Landing Gear (MLG) wheel well pressure floor, resulting in rapid
depressurization. Twenty four operators have reported 67 airplanes
with cracking in the reinforcing beads between BS 910 and BS 940 on
both sides of the airplane between Buttock Line (BL) 10 and BL 50.
The airplanes had accumulated between 12,600 and 43,300 flight cycles
and 18,000 and 51,600 flight hours.
Since Revision 2 five operators reported five airplanes with cracks
outside of the area covered by the modification of the service
bulletin. The cracks were located in the reinforcing beads between BS
910 and BS 930 and between BL 0 and right BL 10. The airplanes had
accumulated between 18,200 and 42,100 flight cycles and 21,300 and
39,900 flight hours.
Revision l was issued to add the installation of stiffening straps at
BS 910 to the preventive modification.  Also added was a new repair
doubler that extended beyond the flanges of the floor beams.
Revision 2 was issued to add the installation of stiffening straps at
BS 910 and 920.  Also added was new repair straps that install over
the doubler at each floor beam.
Revision 3 is issued to provide the recommendation of the Aging Fleet
727 Structures Working Group.
modification kit to install a 0.100 inch thick doubler between BS 910
and BS 930 and between BL 0 and right BL 10.
May 3/14  727-53A0124
REV. 3: Nov 30/89  12

### Page 16 (OCR)

BOEING SERVICE BULLETIN 727-53A0124
C.  Description
Based on a structural review of the 727 airplane, it is recommended
that the modification per Accomplishment Instructions of this service
bulletin be  accomplished prior to, or upon accumulation of 60,000
flight cycles
Inspect pressure floor adjacent to Body Station (BS) 910 floor beam at
or prior to 15,000 flights and thereafter at maintenance intervals of
2000 flight cycles or less until accomplishing preventive modification
or repair per this service bulletin.  Airplanes exceeding this
threshold should be inspected within 800 flight cycles after receipt
of this Revision.  Group 2 and 3 airplanes and airplanes previously
modified require inspection of unmodified areas within 800 flight
cycles after receipt of this Revision and thereafter at 2000 flight
cycle intervals or less until installing the 0.100 inch thick doubler
between BS 910 and BS 930 and between Buttock Line (BL) 0 and right BL
If a visual inspection is performed and evidence of cracking or flaked
paint is detected, verify  cracked condition with eddy current or
penetrant inspection method.
If cracks are detected, perform similar inspection of pressure floor
adjacent to BS 900 and 920 floor beams and install repair doublers as
required prior to next flight. Alternately, If cracks do not exceed
limits specified in Table V, stop drill and seal cracks and install
repair doubler within 600 flights. Repeat inspection of unrepaired
areas at maintenance intervals of 2000 flight cycles or less until
accomplishing the preventive modification or repair per this service
bulletin.
If no cracks are found, accomplish the modification per this Revision
3 or repeat inspection at 2000 flight cycle intervals.
Group 2 and 3 airplanes had  reinforcement straps installed on the
pressure floor at Stations 900, 910 and 920 during production.
Group 3 airplanes had different flap control pulley installed at
Station 918 and right Buttock Line 12.
May 3/74  727-53A0124
REV. 3: Nov 30/89  13

### Page 17 (OCR)

BOLING SERVICE BULLETIN 727-53A0124
This service  bulletin is the subject of  Federal Aviation
Administration (FAA) Airworthiness Directive 77-13-15, Amendment
39-2944.
NOTE: 1. Contact Boeing for instructions if any damaged areas
exceed the specified limits. To expedite Boeing response,
be specific when defining and locating the damage.
Circumstances leading up to the damage and any secondary
effects, when known should be included in the
communication and followed up by sketches and photographs
when appropriate.  In addition, where corrosion is
involved, length, width, and great‹st depth of clean-up
are required.
CONTACT: BOEING COMMERCIAL AIRPLANES
ATTENTION: MANAGER, AIRLINE SUPPORT
2 Due to the corrosion conductive environment of the area
and since corrosion could aggravate the problem described
herein, it is suggested that the operator initiate a
program of corrosion preventive maintenance in the wheel
well, including inspection and restoration of the
protective finish and application of water displacing
corrosion inhibiting compound, with special emphasis upon
the ends of all reinforcing beads in the pressure floor.
Corrosion Prevention Manual, Part II, Subject
53-30-27, Figure 5).
3. This  service bulletin is listed in Boeing Document
D6-54860
4. Concurrent incorporation of Service Bulletin 727-53-0149
is suggested due to similar access requirements.
May 3/14  727-53A0124
FEV. 3: Nov 30/89  14

### Page 18 (OCR)

BOLING S-KVICE BULLETIN 727-53A0124
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.
The interim repair or deferral of repair described in Accomplishment
Instructions, has FAA approval contingent on accomplishment of the
inspections  at the intervals specified in the Accomplishment
Instructions.
The FAA has determined that modification, inspection, and/or repair in
accordance with Revision 3 to Service Bulletin 727-53A0124, 'FUSELAGE
- MAIN WHEEL WELL PRESSURE FLOOR INSPECTION, MODIFICATION AND REPAIRI
is an acceptable alternate means  of compliance for Airworthiness
Directive (AD) 77-13-15, Amendment 39-2944.
The FAA has determined that modification and/or repair in accordance
with Revision 3 to Service Bulletin 727-53A0124, FUSELAGE - MAIN
WHEEL WELL PRESSURE FLOOR INSPECTION, MODIFICATION AND REPAIR is an
acceptable alternate means of compliance for the modifications
specified in Boeing Document D6-54860, which is the subject of Notice
of Proposed Rule Making (NPRM) Docket Number 89-NM-60-AD.
May 3/14  727-53A0124
REV. 3: Nov 30/89  15

### Page 19 (OCR)

BOEING SERVICE BULLET N 727-53A0124
E. Manpower
Approximately 222 man-hours are required to accomplish this
modification per airplane.
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)
Inspection  2  2  2
Modification
Access  32  4
Installation  6  126  21
Restoration  8  48
Operational and
Leak Checks  4  16  4
TOTAL PER AIRPLANE  222  35
May 3/74  727-53A0124
REV. 3: Nov 30/89  16

### Page 20 (OCR)

BOEING SERVICE BULLETIN 727-' .. 0124
F. Material - Price and Availability
The following kit identified in Paragraph II.A may be obtained
from Boeing within the terms and conditions defined below.
quotation indicates the quantity and date when initial kit will
be available.  When source capacity is limited and tooling or
material availability is the pacing factor, operator purchase
orders will receive an allocation from the available quantities
based on receipt date of purchase order by the Spares Department
and based  on operator's planned modification schedules.
Therefore, operators are requested to include planned dates of
incorporation on their purchase orders. When initial quantities
are depleted, additional kits will be available as indicated in
the Reorder  Lead Time (ROLT) column.  Reorder lead time is
computed from date of receipt of operator's purchase orders.
ROLT
Kit Number Description Date  Qty Weeks Unit Price
65-89360-128  Kit  Dec 8, 1989  100  22  $283.00
Date November 30, 1989
The prices quoted are subject to the terms and conditions of
Boeing's standard purchase order acknowledgement. Quotations are
subject to acceptance within 120 days from date hereon. After
expiration of the quotation, price and delivery data will be
provided upon request. Prices quoted in United States Dollars.
Terms: Net 30 days.
Address purchase orders and correspondence pertaining to this
bulletin number.  quotation to Director of Spares, and refer to this service
May 3/74  727-53A0124
REV. 3: Nov 30/89  17

### Page 21 (OCR)

BOEING SERVICE BULLETIN 727-53A0124
2.  The following kits identified in Paragraphs II.A and II.B may be
obtained from Boeing within the terms and conditions defined
The quotation is computed from date of receipt
operator's purchase orders. Improved flow times may be possible
if necessary to support operator's planned modification schedule.
Therefore, operators are requested to include planned dates of
incorporation on their purchase orders.
Kit Number  Description  Delivery  Unit Price
65-89360-5  Kit  37  $ 358.00
65-89360-6  Kit  37  $ 358.00
65-89360-7  Kit  37  $ 184.00
65-89360-8  Kit  37  $ 184.00
65-89360-9  Kit  37  $ 288.00
65-89360-10  Kit  37  $ 288.00
65-89360-11  Kit  37  $ 528.00
65-89360-12  Kit  37  $ 528.00
65-97861-1  Kit  Inactive for procurement
65-97861-2  Kit  Inactive for procurement
65-97861-3  Kit  Inactive for procurement
65-97861-4  Kit-Supplemental  20  $1212.00
65-97861-5  Kit-Supplemental  20  $ 271.00
65-97861-6  Kit  22  $2906.00
Date November 30, 1989
The prices quoted are subject to the terms and conditions of
Boeing's standard purchase order acknowledgement. Quotations are
subject to acceptance within 120 days from date hereon. After
expiration of the quotation, price and delivery data will be
provided upon request. Prices quoted in United States Dollars.
Terms: Net 30 days.
Address purchase orders and correspondence pertaining to this
quotation to Director of Spares, and refer to this service
bulletin number.
G.  Tooling - Price and Availability
None
H. Weight and Balance
Change in  Change in
Weight  Moment
Applicability  (Pounds)  (Pound-Inches)
65-89360-128  + 3.6  + 3312
65-97861-6  +17.4  +15860
May 3/74  727-53A0124
REV. 3: Nov 30/89  18

### Page 22 (OCR)

BOEING SERVICE BULLETIN 727-53A0124
I. References
1.  Existing Data:
a. Engineering Change Memo PRR 23792
b. 727 Structural Repair Manual Subjects 51-30-02 and 51-30-05
c.  Corrosion Prevention Manual, Part II, Subject 53-30-27,
Figure 5
d.  Boeing Standard Overhaul Practices Manual 20-50-12
e.  Boeing Service Bulletin 727-53-0149, FUSELAGE - MAIN WHEEL
WELL PRESSURE FLOOR INSPECTION, MODIFICATION AND REPAIRI
f. FAA Airworthiness Directive 77-13-15, Amendment 39-2944
8 -  Boeing Document D6-54860 ¿Aging Airplane Service Bulletin
Structural Modification Program - Model 727"
2.  Data supplied in support of this service bulletin:
a.  Drawings:
Drawing No.  Sheet  DON  ADCN  Title
65-18745  J  29,30  Pressure Floor
31,32  Installation Main Gear
33  Wheel Well, Sta 870-950
65-89360  2  1  Doubler Installation -
3  C  1  Main Gear Wheel Well
4
7
3.  Process Data:
Boeing  Process  Specifications that are listed  on drawings
supplied in support of this service bulletin are not detailed in
this service bulletin since they are common practices which can
be accomplished in accordance with operator's normal procedures.
J.  Publications Affected
Publication  Chapter-Section
727 Structural Repair Manual..................  53-10
May 3/74  727-53A0124
REV. 3: Nov 30/89  19

### Page 23 (OCR)

BOEING SERVICE BULLETIN 727-53A0124
II. MATERIAL INFORMATION
A. Parts Required Per Airplane
NOTES: 1. The following kits in Table II may be obtained as noted in
Paragraph I.F. or components may be fabricated, as
described, or obtained from operator's inventory or
industry sources, as desired.
2. The following kits and operator furnished materials listed
in Paragraph II.A.2 are required to modify each airplane.
Table II
Kit Applicability
Usage  Applicability  Kit Number  Remarks
Preventive  Sta 900, 910 and 920,  65-97861-6  Supersedes 65-97869-3.
Modification  left and right sides
65-97861-3  Inactive for future
procurement. Supersedes
65-97869-1. Kit
65-97861-3 together
with 65-89360-128 is
equivalent to 65-97869-6
Sta 910, left and  65-97861-1  Inactive for future
right sides  procurement. Supplemented
by 65-97861-4.
Sta 900 and 920, left  65-97861-4  Inactive for future
and right sides  procurement. This kit
together with 65-97869-1
is equivalent to
65-97869-3.
Sta 910 to 930  65-89360-128  This kit together with
65-97869-3 is equivalent
to 65-97869-6.
May 3/74  727-53A0124
REV. 3: Nov 30/89  20

### Page 24 (OCR)

BOEING SERVICE BULLETIN 727-53A0124
Table II - Continued
Usage  Applicability  Kit Number  Remarks
Repair  Sta 900 to 910  65-89360-8  (a)
left side
Sta 900 to 910  65-89360-7  (a)
right side
Sta 910 to 920  65-89360-10  Supersedes 65-89360-1(a)
left side
65-89360-1  Inactive for future
procurement.
Sta 910 to 920  65-89360-9  Supersedes 65-89360-1(a)
right side
65-89360-1  Inactive for future
procurement.
Sta 900 to 920  65-89360-6  (a)
left side
Sta 900 to 920  65-89360-5  (a)
right side
May 3/74  727-53A0124
REV. 3:  Nov 30/89  21

### Page 25 (OCR)

BOEING SERVICE BULLETIN 727-53A0124
Table II - Continued
Usage  Applicability  Kit Number  Remarks
Terminating  Sta 900 and 910 or 910  65-89360-11  Supersedes 65-97861-2
Action  and 920, left or right
side, on which repair
doubler was installed
between those stations
per the original issue
of this bulletin.
Sta 910, left or right  65-97861-2  Inactive for future
side, on which repair  procurement. Supplemented
doubler was installed  by 65-97861-5
between Sta 900 and 910
or 910 and 920 per the
original issue of this
bulletin.
Sta 910 or 920, left or  65-97861-5  This kit together with
right side, on which  65-97861-2 is equivalent
repair doubler was  to 65-89360-11
installed between
Sta 900 and 910 or
910 and 920 per the
original issue of this
bulletin
Sta 910 and 920, left  65-89360-12  (a)
or right side, on which
repair doubler was
installed between these
stations per the
original issue of this
bulletin.
Sta 900, 910 and 920,
left and right side, o
which repair doubler is
required or was installed
per Revision 1 or 2 of
this bulletin.
..  No additional kit
required. Install
applicable strap and
fasteners included in
preventive modification
kit with repair doubler.
(a) Appropriate straps and fasteners of preventive modification kit, 65-97861-3
or equivalent, are to be installed concurrently with this kit.
May 3/74  727 - 53A0124
REV. 3: Nov 30/89  22

### Page 26 (OCR)

BOEING SERV.CE BULIETIN 727-5 A0124
65-89360 - KIT,  DOUBLER INSTALLATION, PRESSURE FLOOR, MAIN GEAR WHEEL WELL
- 8  - 7  - 6  - 5  -1
Quantity  Part Number  Nomenclature
65-89360-1  Kit
65-89360-5  Kit
65-89360-6  Kit
65-89360-7  Kit
65-89360-8  Kit
2  2  2  2  2  65-9220-2 (c)
1  1  1  1  65-9220-56 (c)
2  2  2  2  2  65-9220-57 (c)
1  65-89360-2
2  65-89360-3
1  1  1  65-89360-4 (d)
1  65-89360-14(d)  65-89360-13(d)
65-89360-15(d)
65-89360-16(d)
65-89360-21(d)
69-41867-1
90-4007-3009  Seal
BACB30FP6-5  Bolt
BACB30FP6 - 6  Bolt
2  BACB30FP6-7  Bolt
BACB30FP8 - 5  Bolt
BACB30FQ6 - 6  Bolt
001000  BACB3ONE4-6  Bolt
BACC30M6  Collar
BACC30M8  Collar
4  BACR15BB4A6 (b)  Rivet
6  4  BACR15BB8D12 (a)  BACR15BB8D10  Rivet  Rivet
8  BACR15CE6D12  BACR15CE6D8  Rivet  Rivet
65-89360-9  Kit
65-89360-10  Kit
65-89360-11  Kit
65-89360-12  Kit
65-89360-128  Kit
1  1  2  2  2  2  65-9220-2(c)  65-89360-134  Bracket Installation  Rivet Kit
1  1  65-9220-56(c)  Rivet Kit
2  2  65-9220-57 (c)  Rivet Kit
May 3/74
REV. 3:  Nov 30/89  727-53A0124
23

### Page 27 (OCR)

BOEING SERVICE BULLETIN 727-53A0124
65-89360  (CONTINUED)
- 134  - 128  - 12  - 11  - 10  - 9
Quantity  Part Number  Nomenclature
2  50-3361-2024  Radius Filler
2  50-3361-38  Radius Filler
1  65-89360-4(d)  Filler
1  65-89360-17 (d)  Doubler
65-89360-18(d)  Doubler
1  65-89360-19(d)  Doubler
2  1  65-89360-20(d)  Doubler
2  2  65-89360-21(d)  Filler
1  65-89360-131  Doubler
1  65-89360-132  clip
1  65-89360-133  chip
2  66-17308-1  Fairlead
69-20207-1  Bracket
69-20207-3  Bracket
69-20207-4  Bracket
69-41867-1  Retainer
90-4007-3009  Seal
AN320-5  Nut
AN380-2-1  Pin
AN960-10L  Washer
AN960D516  Washer
AN960PD10  Washer
BACB30FN6A6U  Bolt
2  BACB30FP6-5  Bolt
BACB30FP6-6  Bolt
BACB30FP6 - 7  Bolt
BACB30FP8-5  Bolt
BACB30FQ6 - 6  Bolt
BACB30NE4 - 6  Bolt
4  BACB30FP6A5  Bolt, 1/64 OS
BACB30FP6A6  Bolt, 1/64 OS
-o .  .No.  21  BACC30M6  BACC30M8  Collar  Collar
BACP18C-DD3-178 Pin
2  BACP3OJ7  Pulley
4  4  BACR15BB4A6(b) Rivet
6  6  6  BACR15BB8D10  Rivet
19  6  6  4  BACR15BB8D12(a) Rivet
10  BACR15BB8D14  Rivet
8  8  BACR15CE6D8  Rivet
8  8  8  BACR15CE6D12  Rivet
NAS1105-22D  Bolt
4  NAS623-3-3  Screw
4  NAS679A3W  Nut
2  MS20220-2  Pulley
3  MS24665-132  Cotter Pin
727-53A0124
May 3/14  24
REV. 3:  Nov 30/89

### Page 28 (OCR)

BOEING SERVICE BULLETIN 727-53AU124
65-97861  KIT,  STRAP INSTALLATION, PRESSURE FLOOR MAIN GEAR WHEEL WELL
- 6  - 5  -4  - 3  - 2  - 1
Quantity  Part Number  Nomenclature
65-97861-1  Kit
65-97861-2  Kit
65-97861-3  Kit
65-97861-4  Kit Supplemental
65-97861-5  Kit Supplemental
65-97861-6  Kit
2  2  65-9220-2(c)  Rivet Kit
1  1  1  65-18745-415(d)  Strap
1  1  1  65-18745-416(d)  Strap
1  1  1  65-18745-417 (d)  Strap
1  1  1  65-18745-418 (d)  Strap
65-18745-419 (d)  Strap
65-18745-420(d)  Strap
65-18745-421(d)  Strap
65-18745-422 (d)  Strap
65-18745-423(d)  Strap
65-18745-424(d)  Strap
65-18745-425(d)  Strap
65-18745-426(d)  Strap
65-18745-427 (d)  Strap
65-18745-428(d)  Strap
65-18745-429 (d)  Strap
65-18745-430(d)  Strap
65-18745-431(d)  Strap
65-18745-432 (d)  Strap
65-18745-433(d)  Strap
65-89360-11  Subkit
65-89360-12  Subkit
65-89360-19(d)  Strap
65-89360-20(d)  Strap
65-89360-128  Subkit
May 3/74  727-53A0124
REV. 3: Nov 30/89  25

### Page 29 (OCR)

BOEING SERVICE BULLETIN 727-53A0124
65-97861 -  (CONTINUED)
- 6  - 5  -4  - 3  - 2  -1
Quantity  Part Number  Nomenclature
2  BACB30FP6 -6  Bolt
4  4  4  BACB30FP6-7  Bolt
4  4  4  BACB30FP6-8  Bolt
4  4  4  BACB30FP8 -7  Bolt
4  4  4  BACB30FP8-9  Bolt
4  BACB30FQ6-7  Bolt
8  BACB30FQ6-8  Bolt
18  18  18  BACB30MC6-7
1  1  BACB30MC8 - 6
4  4  4  BACB30NE4-8
16  10  16  16  BACC30M6  Collar
4  4  4  BACC30M8  Collar
18  18  18  BACC30X6  Collar
1  1  BACC30Х6  Collar
16  16  16  BACR15CE6D7  Rivet
562  350  562  212  MS20470D6-12(a) Rivet
96  96  96  MS20470D6-14(a) Rivet
25  6  25  25  MS20470D8-12(a) Rivet
16  16  16  MS20470D8-14(a) Rivet
(a)  MS20470D( )-( ) rivet and BACR15BB( )D( ) or BACRISET( )D( ) rivet may be
used interchangeably.
(b)  MS20470A( )-( ) rivet optional to BACR15BB( )A() rivet.
(c)  Contents of rivet kits are approximately as indicated in Table Ill.
(a)  Indicated parts may be locally fabricated per drawings supplied with this
bulletin from 2024-T3 clad sheet per Specification QQ-A-250/5, stock size
as noted in Table IV.  After trimming to shape, apply chemical film
treatment (Alodine or Iridite) and apply one coat of chemical and solvent
resistant primer (Ref BMS 10-11, Type I).
TABLE III
Rivet Kit Contents
Part Number  Rivet Kit Quantity
65-9220-2  65-9220-56  65-9220-57
BACR15BB6D7  67
BACR15BB6D8  31
BACR15BB6D10  26
BACR15BB6D12  45
BACR15ET7D7
BACR15ET7D8
BACR15ET7D12  34
May 3/74  727-53A0124
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### Page 30 (OCR)

BOEING SERVICE BULLETIN 727-53A0124
TABLE IV
Stocks Sizes Required for Local Fabrication of Parts
Part Number  Stock Size
65-18745-415  0.080 × 3.4 × 25.4
65-18745-416  0.080 × 1.9 X 25.4
65-18745-417  0.080 × 3.4 × 15.2
65-18745-418  0.080 × 2.3 × 15.2
65-18745-419  0.080 × 4.1 × 57.5
65-18745-420  0.080 X 2.9 X 57.5
65-18745-421  0.080 X 3.4 × 57.9
65-18745-422  0.080 × 2.2 × 57.9
65-18745-423  0.080 × 0.6 × 9.3
65-18745-424  0.080 × 2.6 × 9.3
65-18745-425  0.080 × 3.4 × 25.4
65-18745-426  0.080 × 1.9 × 25.4
65-18745-427  0.080 × 2.2 × 57.9
65-18745-428  0.080 x  3.4 X 8.1
65-18745-429  0.080 x  1.9 X 8.1
65-18745-430  0.080  4. 1 X 49.4
65-18745-431  0.080 X 2.9 X 49.4
65-18745-432  0.080  4.1 × 2.9
65-18745-433  0.080  2.9 X 2.9
65-89360-4  0.090  1.0 × 1.3
65-89360-13  0.080  24.0 X 52.0
65-89360-14  0.080 x  24.0 X 52.0
65-89360-15  0.080 X 14.0 X 52.0
65-89360-16  0.080 × 14.0 × 52.0
65-89360-17  0.080 X 14.0 X 52.0
65-89360-18  0.080 × 14.0 × 52.0
65-89360-19  0.160 × 3.6 × 52.0
65-89360-20  0.160 × 3.0 × 52.0
65-89360-21  0.090 × 2.6 x 6.0
2.  The following materials are to be furnished by the operator.
Part Number or
Quantity  Specification  Nomenclature
1/2 Pint  BMS 5-14(a)  Adhesive
4 Quarts  BMS 5-95(a)  Sealant
1/2 Pint  Q30-121(b)  Adhesive
(a)  Refer to applicable  Boeing Material Specification for
qualified products.
(b)  Dow-Corning Corporation
3901 South Saginaw Road
Midland, Michigan 48641-2721
(71984)
May 3/74  727-53A0124
REV. 3: Nov 30/89  27

### Page 31 (OCR)

BOEI G SERVICE BULLETIN 727-53A0124
B. Parts Required to Modify Spares
None
C. Special Tools and Equipment Required
No special tools or equipment are required to accomplish this
bulletin. Maintenance and overhaul tools may be required per any
manuals that are listed in Paragraph I.I., References, of this
bulletin. Operators should review their tool inventory to ensure tool
availability.
D. Existing Parts Accountability
None
May 3/74  727-53A0124
REV. 3:  Nov 30/89  28

### Page 32 (OCR)

BOEING SERVIC BU ETIN 727-53A0124
III. ACCOMPLISHMENT INSTRUCTIONS
NOTES: 1.Observe all warning and caution notes in the referenced manual
sections.
2. As recommended by the 727 Aging Fleet Structures Working Group,
accomplish the modification per this service bulletin, Part Ill
of the Accomplishment Instructions prior to, or  upon the
accumulation of 60,000 flights.
Part I - Inspection
A.  Inspect pressure floor adjacent to Body Station 910 for cracks in both
the right and left main wheel wells per Figure 1.
If no cracks are found, repeat inspection at maintenance intervals of
Modification.  2000 flight cycles or less, until modified per Part Ill Preventive
C.  If cracks are found, perform similar inspection of ends of beads in
pressure floor just forward and aft of Station 900 and 920 floor
beams. Repair all cracks per Part II - Repair, and repeat inspection
of unrepaired areas at maintenance intervals of 2000 flight cycles or
less, until  modified per Part III - Preventive Modification.
Optionally, if cracks do not exceed limits specified in Table V, stop
drill  cracks with 0.190 inch diameter drill, apply pressure and
environmental sealant per operator's standard procedures and repair
per Part II within 600 flight cycles.
TABLE V
Crack Limits
Condition  Crack Limit
One bead cracked and no cracks in  1.00 inch
adjacent beads.
Two adjacent beads cracked and no cracks  1.00 inch, combined
in beads on both sides of cracked pair  length
Three or more adjacent beads cracked.  0.35 inch per bead
D.  If preventive modification straps have been installed at BS 910 only
per Revision 1 of this service bulletin, inspect floor adjacent to
Body Stations 900 and 920 at maintenance intervals of 2000 flight
at these stations also.  cycles or less, until preventive modification or repair is installed
E.  If repair was installed per the original issue of this bulletin,
inspect those areas of the pressure floor adjacent to Body Station
900, 910 and 920, which are not covered by the repair doubler, at
maintenance intervals of 2000 flight cycles or less, until terminating
action or preventive modification straps or additional repair, as
applicable, are installed at these stations.
May 3/74  REV. 3: Nov 30/89  727-53A0124
29

### Page 33 (OCR)

BOEING SERVICE BULLETII 727-53A0124
On Group 2 and 3 airplanes and on Group 1 airplanes preventively
modified per previous issues of this bulletin, inspect those areas of
the pressure floor between Body Station 910 and 930 and between
Buttock Line 0 and right Buttock Line 10, at maintenance intervals of
2000 flight cycles or less, until repaired per Part Il or preventive
modification doubler is installed per Part III.B.
Part II - Repair
Install  repair doublers  and straps as follows and per Drawing
65-89360, Sheet 3, which details separate doubler
configurations suitable for repair of cracks between Stations 900 and
910 only (Kit 65-89360-7 or -8), between 910 and 920 only (Kit
65-89360-9 or -10) or between 900 and 910 as well as between 910 and
920 (Kit 65-89360-5 or -6).
B.  If expedited repair is required, the doubler may be installed, without
gaining access to the upper surface of the pressure floor, with blind
bolts, BACB30LB( )( ), or Visu-Lok PLT210 or PIT 211 blind rivets, at
all fastener locations.  If blind fasteners are installed, however,
they must be reinspected at intervals of approximately 2000 flight
cycles until replaced with fasteners specified of Drawing 65-89360 at
or prior to 10,000 flight cycles.  Install blind bolts (Ref. 727
Structural Repair Manual, Subjects 51-30-02 and 51-30-05). Hole sizes
for installation of blind rivets are specified in Table VI. Airplanes
previously  repaired that have utilized blind fasteners and have
exceeded 10,000 flight cycles should replace blind fasteners with
solid fasteners within 2000 flights cycles after receipt of this
Revision.
NOTES: 1. Shorter or longer doublers than those included in the kits
and shown on Drawing 65-89360, Sheet 3, may be installed
as a repair.
2. If existing repair doubler interferes with new repair, it
will be necessary to remove existing repair doubler and
install new repair that encompasses the old repair area.
3. Straps  and  their attaching fasteners included in
preventive modification Kit, 65-97861-3 or equivalent, are
to be used with the referenced repair kits, since
duplicate straps have not been provided.
4 .  Installation of the repair doubler described in the
original issue of this bulletin and as shown on Drawing
65-89360, Sheet 2, is adequate for repair but is no longer
recommended because of the extensive rework required to
accomplish subsequent terminating action.
May 3/74  727-53A0124
REV. 3: Nov 30/89  30

### Page 34 (OCR)

BOEING SERVICE BULLETIN 727-53AC 24
TABLE VI
Hole Size (in inches) for Installation of Blind Rivets
Hole Size
Nominal
Fastener  Standard  1/64 Oversize
Size  (PLT210)  (PLT211)
3/16  0.199 to 0.202  0.215 to 0.217
1/4  0.260 to 0.263  0.276 to 0.278
C.  Gain access to upper surface of pressure floor by removing floor
panels per operator's standard procedures.
D.  Stop drill both ends of cracks with 0.19 inch diameter drill.
E.  Remove indicated fasteners and related clips and brackets.
F.  Cut out pressure floor as indicated for installation of drain hole
pressure seal, one place in each bay being repaired.
G.  Trim straps, if required, and apply chemical film treatment (Alodine
or Iridite) and one coat of chemical and solvent resistant primer (Ref
BMS 10-11 Type I).
H.  With repair doubler and straps temporarily clamped in place, drill
fastener holes to match existing locations. Drill APU hoist attaching
bolt holes as specified.
I.  Apply prepack and faying surface pressure seals and install straps,
doubler and fillers, if required, as shown. Reinstall removed clips
and brackets on lower surface of doubler or straps.
J.  Drill 0.250 inch diameter drain hole and install pressure seal and
seal retainer.  Bond seal retainer to doubler per 727 Boeing Standard
Overhaul Manual, Subject 20-50-12.
K.  Apply one coat of white enamel (Ref BMS 10-11, Type II) to repair
doubler and straps.
May 3/14  727-53A0124
REV. 3: Nov 30/89  31

### Page 35 (OCR)

BOEING SERVICE BULLETIN 727-53A0124
Part III - Preventive Modification
NOTE: If not accomplished, perform inspection per Part I and accomplish
preventive modification or repair as required.
In areas of floor beams at Body Stations (BS) 900, 910 And 920 which
are not covered by repairs, install Straps, 65-18745-415 through -433
of Kit 65-97861-6 or equivalent per Drawing 65-18745, Sheet 3, Drawing
65-89360, Sheet 7, and as follows:
1.  Trim straps as necessary to accommodate existing repairs. Apply
chemical film treatment (Alodine or Iridite)  and one coat of
chemical and solvent resistant primer (Ref BMS 10-11, Type I) to
bare surfaces.
At locations designated "BM", remove existing fastener and
install MS20470D( )-( ) rivet. At locations designated "XF",
install BACB15CE( )D( ) rivet.
3.  Remove and reinstall APU generator hoist fitting at BS 900, Left
Buttock Line (LBL) 18, With four BACB30FP6-8 bolts and BACC30M6
collars installed in 0.200 (+0.003 or -0.000) inch diameter
holes.
At the APU hoist attach points at BS 900, RBL 28 and BS 920. RBL
51, remove radius filler attaching fasteners and install four
Bolts BACB30FQ6-8 and collars BACC30M6 at each station in 0.200
(+0.003 or -0.000) inch diameter holes. Replace existing bolts
with BACB30NE4-8 bolts (2 places each station).
5.  Remove two intercostal tee attach fasteners at BS 900, right and
left BL 30 and install Bolts BACB30FP6-7 and Collars BACC30M6 in
0.200 (+0.003 or -0.000) inch diameter holes.
Remove two intercostal tee attach fasteners at BS 900, right and
left BL 46  and install bolts BACB30FP8-7 or -9 and collars
BACC30M8 in 0.263 (+0.003 or -0.000) inch diameter holes.
7.  Remove hydraulic tubing support bracket attach fasteners at BS
900, LBL 54 and install bolt BACB30MC8-6 and collar BACC30X8 in
0.263 (+0.003 or -0.000) inch diameter hole.
At BS 920, remove the nine aft fasteners at locations common to
the new straps between right and left BL 20 and BL 30 and replace
with BACB30MC6-7 bolts and BACC30X6 collars installed in 0.200
Apply one coat of white enamel (Ref BMS 10-11, Type II) to
installed straps.
May 3/74  727-53A0124
REV. 3: Nov 30/89  32

### Page 36 (OCR)

BOEING SERVICE BULLETIN 727-53A0124
In area between Body Stations (BS) 910 and 930 and between Buttock
Line (BL) 0 and right BL 10 which are not covered by repairs, install
Doubler 65-89360-131 per Drawing 65-89360, Sheet 7 and as follows:
Trim ends of Straps 65-18745-428, -429, -430, and -431 installed
in step III.B. as shown in zone D11.  Apply chemical film
treatment (Alodine or Iridite) and one coat of chemical and
solvent resistant primer to bare surface.
Remove and discard existing pulley bracket assembly 65-26196-3
two angles 65-18745-234 and filler 65-18745-225.
Remove existing fasteners as indicated on drawing installation
65-89360-128 shown in zone B10.
Remove  and discard bracket 69-20207-3 from pulley bracket
69-20207-1.
5.
Install doubler 65-89360-131, two angles 65-18745-234, filler
65-18745-225, bracket 69-20207-4, 65-89360-132, and 65-89360-133
using fastener BACR15BB( )D( ) at locations designated "XZK" with
manufactured head on upper side of web.
Apply one coat of white enamel (Ref BMS 10-11, Type II) to
installed doubler.
8 .  Install pulley bracket 69-20207-1 and two fairleads 66-17308-1.
9.  Group 1  and 2 airplanes - Install two flap control pulleys
MS20220-2.
10. Group 3 airplanes - Install two flap control pulleys BACP3OJ7.
11. Adjust flap control pulleys ( on Group 1 and 2) MS20220-2 or (on
Group 3) BACP3OJ7 to align with outboard trailing edge flap
control valve assembly 65-23552-() and inboard flap control shaft
assembly 65-24593-().
May 3/74  727-53A0124
REV. 3: Nov 30/89  33

### Page 37 (OCR)

BOEING SERVICE BULLETIN 727-53A0124
Part IV - Terminating Action For Airplanes Repaired Per Original Issue or
Revision 1 of this service bulletin
If repair doubler was installed between Body Station (BS) 900 and
BS 910 or between BS 910 and BS  920 per original issue of this
bulletin, install straps of Kit 65-89360-1l, or equivalent, at the
forward and aft edges of the doubler per Drawing 65-89360, Sheet 4,
and as follows:
1. If repaired, cut straps to length and apply chemical film
treatment (Alodine or Iridite) and one coat of chemical and
solvent resistant primer (Ref BMS 10-11, Type I) to bare surface.
2.  Apply one coat of white enamel (Ref BMS 10-11, Type II) to
installed straps.
B. If repair doubler was  installed between BS 900 and BS 920 per the
original issue of this bulletin, install straps of Kit 65-89360-12 at
forward and aft edges of doubler per Drawing 65-89360, Sheet 4, and
install strap and fasteners of preventive modification Kit 65-97861-3
at BS 910 per Drawing 65-89360, Sheet 3 and Steps A.1 and A.2 above.
If repair doubler was installed per Revision l of this bulletin,
install straps and fasteners of preventive modification Kit 65-97861-6
at applicable floor beam stations per Drawing 65-89360, Sheet 3, and
Steps A.1 and A.2 above.
May 3/74  727-53A0124
REV. 3: Nov 30/89  34

### Page 38 (OCR)

BOEING : ERVICE BUL ETIN 727-53A0124
STA
950
STA
910  SEE DETAIL I
STA
870
LEFT SIDE MAIN WHEEL WELL SHOWN,
RIGHT SIDE OPPOSITE
STA
910
NOTE: Strip paint prior to penetrant inspection to ensure accurate results.
(Preferred) Perform eddy current or penetrant inspection per operator's
standard procedure, of ends of beads in pressure floor just forward and aft
of Body Station 910 floor beam across entire width of wheel well.
(Optionally) Perform a close visual inspection of the area.  If any
indication of distress such as cracking or flaked paint is found, perform
eddy-current or penetrant inspection to confirm and determine true extent
of cracking.
FIGURE 1. INSPECTION OF MLG WHEEL WELL PRESSURE FLOOR
мау 3/14  727-53A0124
REV. 3:  Nov 30/89  35

### Page 39 (OCR)

BOEING
SERVICE BULLETIN
EVALUATION FORM
THIS EVALUATION FORM IS PROVIDED FOR THE PURPOSE OF COMMUNICATING INFORMATION TO
THE BOEING ORGANIZATION RESPONSIBLE FOR SERVICE BULLETINS AND THEIR CONTENT. THE
DATA YOU PROVIDE WILL BE USED TO IMPROVE THE BOEING SERVICE BULLETIN PROGRAM.
NOTE: THIS FORM IS NOT INTENDED TO BE USED FOR REQUESTING SERVICE BULLETIN
INCORPORATION INTO BOEING TECHNICAL MANUALS.
S/B NO.:  727-53A0124 (REV. 3)  S/B DATED: NOVEMBER 30, 1989
TITLE:  FUSELAGE - MAIN WHEEL WELL PRESSURE FLOOR INSPECTION,
MODIFICATON AND REPAIR
OPERATOR:  AIRPLANES AFFECTED  → per S/B effectivity list
(check one) :  Oper corrected list below:
PREPARED BY:  TITLE:  DATE:
ORGANIZATION:  TELEX CODE:
EVALUATION:
check ONE of the following  five circles  AND  check ONE of the following  seven circles.
• - Wi11 accomplish  - Inspection
- Being accomplished  - Partial incorporation
- Have accomplished  - Complete incorporation
- Service bulletin intent
- Will not accomplish  - Uneconomical
- Decision deferred (explain)  - Service experience does not justify
- Other (explain below)
COMMENTS: Bulletin Quality, Suggested Improvements, Other.
FOR ADDITIONAL COMMENTS USE REVERSE SIDE
directly to:  Please forward this form to your Boeing Field Service Representative or mail
Attention: R. G. Kelsey
Seattle, WA 98124  Boeing Commercial Airplanes  P.O. Box 3707  Manager,  Service Bulletin Engineering  Mail Stop 21-02

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