# Aviation Partners Boeing Service Bulletin AP737C-57-002

Copy: No revision named ("AP737C-57-002"), 15 pages: PDF https://openairdocs.org/files/sha256/8e/30/8e30271cc0754fe772232ece09e61bb979ccaa536330c0f788cf00351143c942; text https://openairdocs.org/service-documents/aviation-partners-boeing/ap737c-57-002/file/8e30271cc075.md. Rights: © Aviation Partners Boeing. Filed by the FAA in regulations.gov docket FAA-2017-0903; AD 2018-06-05 incorporates this document by reference. Not covered by OpenAirDocs’ CC0 dedication.

## Details

- Manufacturer: [Aviation Partners Boeing](https://openairdocs.org/service-documents/aviation-partners-boeing.md)
- Type: Service bulletin (Service Bulletin)
- Number: AP737C-57-002
- Page: https://openairdocs.org/service-documents/aviation-partners-boeing/ap737c-57-002

## ADs that cite it (1) (OpenAirDocs)

Newest first, with the revision each names, as OpenAirDocs read it from the AD's text.

- [AD 2018-06-05](https://openairdocs.org/ad/2018-06-05.md), effective Apr 23, 2018: No revision named

Also cited in [1 proposed AD](https://openairdocs.org/service-documents/aviation-partners-boeing/ap737c-57-002/proposed.md).

## Text (15 pages)

Rights: © Aviation Partners Boeing. Filed by the FAA in regulations.gov docket FAA-2017-0903; AD 2018-06-05 incorporates this document by reference. Not covered by OpenAirDocs’ CC0 dedication. Some pages are 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)

U.S DEPARTMENT OF TRANSPORTATION  1. DATE
STATEMENT OF COMPLIANCE WITH AIRWORTHINESS STANDARDS  FEDERAL AVIATION ADMINISTRATION  May 3, 2017
AIRCRAFT OR AIRCRAFT COMPONENT IDENTIFICATION
2. MAKE  3 MODEL NO  4. TYPE (Aircraft, Engine, Propeller, etc ))  5. NAME OF APPLICANT
Boeing  737-300  Airplane  Aviation Partners Boeing
737-500
LIST OF DATA
6. IDENTIFICATION  7. TITLE
Doc. No. Rev Date  Document Title
AP737C-57-002  WINGS - Lower Skin at Stringer L-5 Runout at Wing Station 488-Inspection
Rev: IR
Date: April 5, 2017
This Service Bulletin was reviewed for technical accuracy by DER James Haynes
(DERY-635780-NM)
25/4/17
Note: The Recommend Approval is for Structural aspects only.
8. PURPOSE OF DATA
In support of 737-300/-500 Winglet Program STC# ST01219SE
9. APPLICABLE REQUIREMENTS (List specific sections)
14 CFR Part 25 Sections 25.571 (a)(b)(amdt 25-86)
14 CFR Part 26 Sections 26.47 (c)(d) (amdt 26-1)
10. CERTIFICATION - Under authority vested by direction of the Administrator and in accordance with conditions and limitations of appointment
under 14 CFR Part 183, data listed above and on attached sheets numbered  n/a  have been examined in accordance with established
procedures and found to comply with applicable requirements of the Airworthiness Standards listed.
Recommend approval of these data
I (We) Therefore  Approve these data
11, SIGNATURE(S) OF DESIGNATED ENGINEERING REPRESENTATIVE(S)  12. DESIGNATION NUMBERS(S)  13. CLASSIFICATION(S)
Jason Dai  DERT-636402-NM  Structures
→750.D
FAA Form 8110-3 (03/10) SUPERSEDES PREVIOUS EDITION

### Page 2

AVIATION PARTNERS BOEING SERVICE BULLETIN 
2811 S 102nd Street, Suite 200 
Seattle, WA 98168 
(206) 830-7699 
Original Issue: April 5, 2017 AP737C-57-002 
 Page i 
Aviation Partners Boeing Proprietary 
NUMBER: AP737C-57-002 Transmittal Sheet 
Original Issue: April 05, 2017  
ATA SYSTEM: 5720   
SUBJECT: WINGS - Lower Wing Skin at Stringer L-5 Runout at Wing Station 488 - Inspection

### Page 3

AVIATION PARTNERS BOEING SERVICE BULLETIN AP737C-57-002 
Original Issue: April 5, 2017 AP737C-57-002 
 Page ii 
Aviation Partners Boeing Proprietary 
APB DOCUMENT FEEDBACK FORM 
To provide feedback on this document to APB for corrections or improvements, please complete the form below 
and fax or email to the attention of APB Liaison Engineering at: 
Fax: +1 (206) 767-0535 
Email: leng@aviationpartners.com 
Airline Name: ______________________________________________ 
Contact Name: ______________________________________________ 
Phone Number: ______________________________________________ 
Email Address: ______________________________________________ 
Airplane Model-Type: ______________________________________________ 
Document Number: ______________________________________________ 
Document Revision: ______________________________________________ 
Document Title: ______________________________________________ 
Chapter-Section-
Subject: ______________________________________________ 
Page: ______________________________________________ 
Page Date: ______________________________________________ 
Description of Change: 
(Include additional 
sheets as required) 
 
 
 
 
 
 
 
 
 
 
 
 
 
Attachments: ______________________________________________

### Page 4

AVIATION PARTNERS BOEING SERVICE BULLETIN 
2811 S 102nd Street, Suite 200 
Seattle, WA 98168 
(206) 830-7699 
 
Original Issue: April 5, 2017 AP737C-57-002 
 Page 1 of 12 
 
NUMBER: AP737C-57-002  
Original Issue: April 05, 2017  
ATA SYSTEM: 5720 
SUBJECT: WINGS - Lower Wing Skin at Stringer L-5 Runout at Wing Station 488 - Inspection 
 
PROPRIETARY NOTICE 
 
The data contained hereon and herein is proprietary to Aviation Par tners Boeing. Neither this data nor the data 
contained herein shall be reproduced, used or disclosed to others without the written authorization of Aviation 
Partners Boeing. 
 
EXPORT CONTROLLED TECHNOLOGY 
 
This document contains information about a technology controlled by the Export Administration Regulations (EAR) 
(15 CFR 730-774). It has been classified under Export Control Classification Number (ECCN) 9E991 and may not 
be exported to certain countries without a license. Providing this information to a foreign national - inside or outside 
the United States - can constitute a prohibited export. Each person handling this document has a legal responsibility 
to comply with all applicable EAR requirements and should consult with an Export Control Officer before  providing 
it to any foreign national.

### Page 5

AVIATION PARTNERS BOEING SERVICE BULLETIN AP737C-57-002 
Original Issue: April 5, 2017 AP737C-57-002 
 Page 2 of 12 
Aviation Partners Boeing Proprietary 
Table of Contents 
Table of Contents .......................................................................................................................................................2 
1. PLANNING INFORMATION .......................................................................................................................3 
A. Effectivity ....................................................................................................................................................3 
1. Airplanes .....................................................................................................................................................3 
2. Spares Affected ..........................................................................................................................................3 
B. Concurrent Requirements...........................................................................................................................3 
C. Reason........................................................................................................................................................3 
D. Description ..................................................................................................................................................3 
E. Compliance .................................................................................................................................................4 
F. Approval ......................................................................................................................................................4 
G. Warranty Information ..................................................................................................................................4 
H. Manpower ...................................................................................................................................................4 
I. Weight and Balance Changes ....................................................................................................................5 
J. Electrical Load Data ....................................................................................................................................5 
K. References .................................................................................................................................................5 
1. Existing Data: ..............................................................................................................................................5 
2. Data Supplied with This Service Bulletin: ...................................................................................................5 
3. Installation Drawings Used in the Preparation of This Service Bulletin: .....................................................5 
L. Other Publications Affected ........................................................................................................................5 
1. Publications ................................................................................................................................................5 
2. Damage Tolerance Based Structural Inspections: .....................................................................................5 
M. Interchangeability and Intermixability of Parts ............................................................................................5 
N. Software Accomplishment Summary ..........................................................................................................5 
2. MATERIAL INFORMATION........................................................................................................................6 
A. Material - Price and Availability ..................................................................................................................6 
B. Parts Necessary for Each Airplane .............................................................................................................6 
C. Parts Necessary to Change Spares ...........................................................................................................6 
D. Existing Parts Accountability ......................................................................................................................6 
E. Special Tooling - Price and Availability .......................................................................................................6 
F. Special Tooling Necessary to Do This Service Bulletin ..............................................................................6 
3. ACCOMPLISHMENT INSTRUCTIONS ......................................................................................................7 
A. General Notes .............................................................................................................................................7 
B. Work Instructions ........................................................................................................................................7 
PART 1: DET INSPECTION OF LOWER WING SKIN EXTERNAL SURFACE – OUTBOARD RUNOUT OF 
STRINGER L-5 ......................................................................................................................................7 
FIGURE 1: LOWER WING SKIN SURFACE .............................................................................................................8 
FIGURE 2: OUTBOARD LOWER WING SKIN AT RUNOUT OF STRINGER L-5 ....................................................9 
APPENDIX A: REPORTING INSTRUCTIONS: ...................................................................................................... 11

### Page 6

AVIATION PARTNERS BOEING SERVICE BULLETIN AP737C-57-002 
Original Issue: April 5, 2017 AP737C-57-002 
 Page 3 of 12 
Aviation Partners Boeing Proprietary 
1. PLANNING INFORMATION 
A. Effectivity 
1. Airplanes 
This service bulletin is applicable to 737-300 and 737-500 Airplanes with blended winglets (Refer to 
STC ST01219SE).  
GROUP CONFIGURATION DESCRIPTION 
1 - 737-300/-500 Airplanes with APB blended winglet kit 
2. Spares Affected 
None 
 
B. Concurrent Requirements 
None. 
 
C. Reason 
This service bulletin gives instructions to inspect the lower wing skin on left and right wing to find skin 
crack(s). This service bulletin also gives additional inspection requirements that will more quickly help 
detect any future cracks in the wing lower skin common to the outboard segment of the stringer L-5 at 
runout at WSTA 488. 
If not reliably detected, fatigue cracking of the lower wing skin common to the runout of stringer L-5 could 
grow and result in a loss of the structural integrity of the wing.  
Fatigue cracks have been found in the lower wing skin at the farthest outboard fastener of stringer L-5 
between WSTA 479 and WSTA 505 on one passenger (737-300) airplane with winglets installed. The 
cracks were found at the furthest outboard fastener hole common to the stringer on the left-hand wing.  
This Service Bulletin gives inspection instructions and requirements.  See FIGURE 1 for the areas of 
inspection. 
 
D. Description 
This service bulletin gives instructions to do the following. 
• A repetitive detailed (DET) Inspection of the lower outboard wing skin external surface at the 
outboard end runout location of stringer L-5 to find crack(s).  
 
The inspection work in this service bulletin is done in the maintenance zone(s) given below. 
Affected Maintenance Zones 
Model Zone 
737-300, 737-500 305, 405

### Page 7

AVIATION PARTNERS BOEING SERVICE BULLETIN AP737C-57-002 
Original Issue: April 5, 2017 AP737C-57-002 
 Page 4 of 12 
Aviation Partners Boeing Proprietary 
E. Compliance 
The FAA will possibly release an Airworthiness Directive related to this service bulletin. The Airworthiness 
Directive will make the compliance tasks and times given in this service bulletin mandatory.  
Group 1: 
 
Condition Action Compliance Time  
 
Repeat Interval (Not to 
Exceed) 
All airplanes Do PART 1: DET 
Inspection of Lower Wing 
skin external surface – 
outboard runout of Stringer 
L-5 on left and right wing. 
Within 18 months after the 
initial issue date of this 
service bulletin 
 
Condition 1:  
No crack found 
Do PART 1: DET 
Inspection of Lower Wing 
skin external surface – 
outboard runout of Stringer 
L-5 on left and right wing. 
 
 
6,000 flight cycles 
OR 
9,000 flight hours, 
whichever occurs first. 
Condition 2:  
Any crack found 
Contact The Boeing 
Company for repair 
instruction and do the 
repair as instructed. 
Before further flight  
 
F. Approval 
This service bulletin was examined by the Federal Aviation Administration (FAA). The inspections 
specified in this service bulletin comply with the applicable regulations and are FAA approved, as well as 
European Aviation Safety Agency (EASA)/Joint Aviation Authorities (JAA) approved for all EASA/JAA 
approved airplanes listed in the service bulletin effectivity. This service bulletin and its approval were 
based on the airplane in its original Boeing delivery configuration and subsequently modified in 
accordance with Aviation Partners Boeing STC ST01219SE or as modified by other approved Boeing 
changes. 
If an airplane has a non-Boeing modification or repair that affects a component or system also affected by 
this service bulletin, the operator is responsible for obtaining appropriate regulatory agency approval 
before incorporating this service bulletin. 
 
G. Warranty Information 
Aviation Partners Boeing warranty remedies are not available for the inspection procedures given in this 
service bulletin.  
H. Manpower 
Approximately ½ man-hour and 1 person are needed to perform the inspection. The table below shows 
an estimate of the task hours necessary to do this inspection for each airplane. This estimate is for direct 
labor only, done by an experienced crew. Adjust the estimate with operator task hour data if necessary. 
The estimate does not include lost time. These are some examples of lost time:  
• Time to adjust to the workplace 
• Time to schedule the inspection

### Page 8

AVIATION PARTNERS BOEING SERVICE BULLETIN AP737C-57-002 
Original Issue: April 5, 2017 AP737C-57-002 
 Page 5 of 12 
Aviation Partners Boeing Proprietary 
 
PART 1: DET INSPECTION OF LOWER WING SKIN EXTERNAL SURFACE – OUTBOARD RUNOUT OF 
STRINGER L-5 
Task Number of Persons Man-Hours Elapsed Time 
(Hours) 
Inspection 1 0.5 0.5 
TOTAL FOR EACH AIRPLANE 0.5 0.5 
 
I. Weight and Balance Changes 
None. 
 
J. Electrical Load Data 
None. 
K. References 
1. Existing Data: 
a. D6-3(xxxx) Boeing 737-300,-500 Aircraft Maintenance Manual (AMM).(xxxx) Refers to customer 
specific code. 
2. Data Supplied with This Service Bulletin: 
None. 
3. Installation Drawings Used in the Preparation of This Service Bulletin: 
Drawing Number Title 
65-45470 SH3 Splice Instl – Forward & Aft Skin, Lower Panel F.S.S. 429.20 & W.S. 463.85 
This drawing was used to prepare this service bulletin. This drawing is not necessary to conduct the 
specified inspections, and is not supplied with this service bulletin. This drawing may not be 
applicable to all airplane configurations or operators. 
L. Other Publications Affected 
1. Publications 
None. 
2. Damage Tolerance Based Structural Inspections: 
APB has evaluated the changes in this service bulletin for effects on Fatigue Critical Structure (FCS) 
and for changes to Damage Tolerance Inspections (DTI) required in the Maintenance Program. This 
service bulletin affects FCS and changes to DTI were necessary. DTI requirements for the structure 
affected are contained in Paragraph 1.E., Compliance of this service bulletin. 
M. Interchangeability and Intermixability of Parts 
None. 
N. Software Accomplishment Summary 
None.

### Page 9

AVIATION PARTNERS BOEING SERVICE BULLETIN AP737C-57-002 
Original Issue: April 5, 2017 AP737C-57-002 
 Page 6 of 12 
Aviation Partners Boeing Proprietary 
2. MATERIAL INFORMATION 
A. Material - Price and Availability 
None. 
B. Parts Necessary for Each Airplane 
None. 
C. Parts Necessary to Change Spares 
None. 
D. Existing Parts Accountability 
N/A. 
E. Special Tooling - Price and Availability 
No special tooling is required to do repairs. 
F. Special Tooling Necessary to Do This Service Bulletin 
Maintenance and overhaul tools as specified in the maintenance manuals may be necessary. Examine 
operator tool supply before starting work to make sure all necessary tools are available.

### Page 10

AVIATION PARTNERS BOEING SERVICE BULLETIN AP737C-57-002 
Original Issue: April 5, 2017 AP737C-57-002 
 Page 7 of 12 
Aviation Partners Boeing Proprietary 
3. ACCOMPLISHMENT INSTRUCTIONS 
A. General Notes 
WARNING:  IF ELECTRICAL POWER IS APPLIED TO THE AIRPLANE, MAKE SURE YOU OBEY ALL 
PRECAUTIONS WHILE YOU DO WORK. IF YOU DO NOT OBEY THE PRECAUTIONS, 
DEATH OR INJURY TO PERSONS, AND DAMAGE TO THE AIRPLANE CAN OCCUR.  
NOTE: 1. Obey all warnings and cautions given in the applicable sections of the Aircraft Maintenance 
Manual (AMM). 
2. Make an entry into aircraft maintenance records once service bulletin is completed.  
3. These work instructions refer to procedures included in other Boeing documents. When the 
words “refer to” are used and the operator has an accepted alternative procedure, the 
accepted alternative procedure can be used. When the words “in accordance with” are 
included in the instruction, the procedure in the document must be used. 
4. When more than one OPTION is given for a CONDITION, do only one of the OPTION 
numbers. When more than one ACTION is given for a CONDITION number or an OPTION 
number, do all of the ACTION numbers for that CONDITION number or OPTION number.  
5. Some steps in the Work Instructions are labeled as Required for Compliance (RC). If this 
service bulletin is mandated by an airworthiness directive (AD), then the steps labeled RC, 
including sub-steps under an RC step and any figures identified in an RC step, must be done 
to comply with the AD. An Alternative Method of Compliance (AMOC) is required for any 
deviations to RC steps, including sub-steps and identified figures. Steps not labeled as RC 
may be deviated from using accepted methods in accordance with the operator’s 
maintenance or inspection program without getting approval of an AMOC. This is provided 
that the RC steps, including sub-steps and identified figures, can still be done as specified, 
and the airplane can be put back in an airworthy condition. 
6. The compliance times for the actions in Paragraph 3.B., WORK INSTRUCTIONS are in 
Paragraph 1.E., Compliance. 
7. A Detailed Inspection is defined as: An intensive examination of a specific item, installation, 
or assembly to detect damage, failure, or irregularity. Available lighting is normally 
supplemented with a direct source of good lighting at an intensity deemed appropriate. 
Inspection aids such as mirrors, magnifying lenses, etc. may be necessary. Surface cleaning 
and elaborate procedures may be required. 
B. Work Instructions 
PART 1: DET INSPECTION OF LOWER WING SKIN EXTERNAL SURFACE – OUTBOARD RUNOUT 
OF STRINGER L-5 
NOTE: Aviation Partners Boeing requests the operators to report the results of inspection to Aviation 
Partners Boeing. See Appendix A for recommended format for crack finding reports. 
1. RC - Do a detailed (DET) surface inspection of the Lower Wing Skin external surface – Stringer 
L-5 Runout location to detect crack(s) in accordance with FIGURE 2. 
a. Condition 1 – If no crack is found, 
Repeat PART 1: Do a detailed (DET) surface inspection of the Lower Wing Skin external 
surface – Stringer L-5 Runout. 
 
b. Condition 2 – If any crack is found,  
Contact The Boeing Company for repair instruction and do the repair as instructed.

### Page 11

AVIATION PARTNERS BOEING SERVICE BULLETIN AP737C-57-002 
Original Issue: April 5, 2017 AP737C-57-002 
 Page 8 of 12 
Aviation Partners Boeing Proprietary 
 
 
 
 
 
 
 
 
 
 
 
 
FIGURE 1: LOWER WING SKIN SURFACE 
  Left Wing Shown (Right Wing Opposite) 
  
Inspection Area 
Lower Wing Skin 
Rear Spar 
A 
RSS 
135.24 
RSS 
280.00 
RSS 
479.00

### Page 12

AVIATION PARTNERS BOEING SERVICE BULLETIN AP737C-57-002 
Original Issue: April 5, 2017 AP737C-57-002 
 Page 9 of 12 
Aviation Partners Boeing Proprietary 
 
 
 
 
 
 
 
 
 
 
 
 
FIGURE 2: OUTBOARD LOWER WING SKIN AT RUNOUT OF STRINGER L-5  
DET EXTERNAL SURFACE INSPECTION 
Left Side Shown, Right Side Opposite 
(SHEET 1 OF 2)  
RIB  
WSTA 
509.0 
RIB  
WSTA 
479.0 
STRINGER 
L-6 
STRINGER 
L-8 
Rear Spar 
OUTBD RUNOUT 
OF WING 
STRINGER L-5 
INBD 
FWD 
View Looking Down

### Page 13

AVIATION PARTNERS BOEING SERVICE BULLETIN AP737C-57-002 
Original Issue: April 5, 2017 AP737C-57-002 
 Page 10 of 12 
Aviation Partners Boeing Proprietary 
 
 
 
 
 
 
 
 
 
 
The step numbers shown below agree with the numbers shown in the circle symbo ls in the figure. 
 
 
 
 
 
 
FIGURE 2: OUTBOARD LOWER WING SKIN AT RUNOUT OF STRINGER L-5  
DET EXTERNAL SURFACE INSPECTION 
Left Side Shown, Right Side Opposite 
(SHEET 2 OF 2) 
 
  
Step Task Name Identification Qty More Data 
1 Inspect Wing Skin around Fasteners - 5 (a) 
(a)  Do DET external surface inspection to detect cracks.  
WING STRINGER L-5 
1 
INBD 
FWD 
View Looking Up 
REAR SPAR  
Trace  
WS 479.00

### Page 14

AVIATION PARTNERS BOEING SERVICE BULLETIN AP737C-57-002 
Original Issue: April 5, 2017 AP737C-57-002 
 Page 11 of 12 
Aviation Partners Boeing Proprietary 
APPENDIX A: REPORTING INSTRUCTIONS:  
 
1. Document the results of a hole/skin inspection at the fastener locations with crack indications. Also document 
crack length and in which part, and show crack orientation (direction) on the graphics given in this Appendix.  
2. Send this data to Aviation Partners Boeing. Please complete the form below and fax or email to the attention of 
APB Liaison Engineering at: 
Fax: +1 (206) 767-0535 
Email: leng@aviationpartners.com 
 
 
 
 
 
 
 
 
 
 
Left Side Shown, Right Side Opposite 
 
FIGURE A: INSPECTION DATA – OUTBOARD LOWER WING SKIN AT RUNOUT OF STRINGER L-5  
DET EXTERNAL SURFACE INSPECTION 
 
(SHEET 1 OF 2)  
1 
 2 
 4 
3 
 5 
WING STRINGER L-5 
REAR SPAR 
FWD 
INBD 
View Looking Up 
Trace  
WS 479.00

### Page 15

AVIATION PARTNERS BOEING SERVICE BULLETIN AP737C-57-002 
Original Issue: April 5, 2017 AP737C-57-002 
 Page 12 of 12 
Aviation Partners Boeing Proprietary 
VARIABLE SERIAL REGISTRY FLIGHT CYCLES FLIGHT HOURS 
# #    
 
LEFT SIDE WING - FINAL HOLE DIAMETER AND CRACK DATA 
CRACK INDICATION: YES or NO 
If YES, please fill out the table below. 
HOLE NUMBER FINAL DIAMETER (IN) EDGE MARGIN (IN) CRACK LENGTH (IN)/PART 
    
    
    
    
    
    
    
    
 
RIGHT SIDE WING - FINAL HOLE DIAMETER AND CRACK DATA 
CRACK INDICATION: YES or NO 
If YES, please fill out the table below. 
HOLE NUMBER FINAL DIAMETER (IN) EDGE MARGIN (IN) CRACK LENGTH (IN)/PART 
    
    
    
    
    
    
    
    
 
 
Figure A: INSPECTION DATA – OUTBOARD LOWER WING SKIN AT RUNOUT OF STRINGER L-5  
DET EXTERNAL SURFACE INSPECTION 
 
(SHEET 2 OF 2)

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