Commercial 

Airplanes 737

Service Bulletin

ALERT

Number: 737-53A1318

Original Issue: October 31, 2011

ATA System: 5331

SUBJECT: FUSELAGE - Skin - Skin Cracking at the Aft Waste Water Drain Mast - Inspection and

Repair

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2.0
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BLANK PAGE
Table of Contents

Summary ...................................................... 5

1. PLANNING INFORMATION ........................................ 9

A. Effectivity ................................................ 9

1. Airplanes ............................................. 9

2. Spares Affected . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17

B. Concurrent Requirements . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17

C. Reason . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17

D. Description . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18

E. Compliance . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18

F. Approval . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20

G. Manpower . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20

H. Weight and Balance Changes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21

I. Electrical Load Data . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21

J. References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22

1. Existing Data . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22

2. Data supplied with this Service Bulletin . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22

3. Installation Drawings Used in the Preparation of this Service Bulletin . . . . . . . . . . . . 22

K. Publications Affected . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22

L. Interchangeability and Intermixability of Parts . . . . . . . . . . . . . . . . . . . . . . . . . . . 23

2. MATERIAL INFORMATION . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 25

A. Material - Price and Availability . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 25

B. Industry Support Information . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 25

C. Parts Necessary For Each Airplane . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 25

1. Kits/Parts . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 25

2. Parts and Materials Supplied by the Operator . . . . . . . . . . . . . . . . . . . . . . . . 25

3. Parts Modified and Reidentified . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 25

4. Parts Removed and Not Replaced . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 25

D. Parts Necessary to Change Spares . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 25

E. Special Tooling - Price and Availability . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 26

F. Special Tooling Necessary to do this Service Bulletin . . . . . . . . . . . . . . . . . . . . . . . 26

3. ACCOMPLISHMENT INSTRUCTIONS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 27

A. GENERAL INFORMATION . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 27

B. WORK INSTRUCTIONS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 28

FIGURE 1: GET ACCESS TO THE DRAIN MAST SUPPORT STRUCTURE [Group 1] . . . . . . . . 31

FIGURE 2: DO A DETAILED INSPECTION OF THE CHANNEL AND THE FILLERS [Group 1] . . . . 34

FIGURE 3: INSPECT THE BONDING STRAP LOCATION [Group 1] . . . . . . . . . . . . . . . . . . 36

FIGURE 4: MEASURE THE DIAMETER OF THE WASHERS UNDER THE DRAIN MAST BOLTS [Group

1] . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 38

FIGURE 5: MEASURE THE THICKNESS OF THE WASHERS UNDER THE DRAIN MAST BOLTS -

INSTRUMENT METHOD [Group 1] . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 40

FIGURE 6: MEASURE THE THICKNESS OF THE WASHERS UNDER THE DRAIN MAST BOLTS -

OPTIONAL TOOL METHOD [Group 1] . . . . . . . . . . . . . . . . . . . . . . . . . . . . 43

FIGURE 7: REMOVE THE DRAIN MAST [Group 1] . . . . . . . . . . . . . . . . . . . . . . . . . . . . 47

FIGURE 8: DO AN HFEC AND DETAILED INSPECTION OF THE SKIN, THE CHANNEL, AND THE FILLERS

[Group 1] . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 49

FIGURE 9: INSTALL THE DRAIN MAST [Group 1] . . . . . . . . . . . . . . . . . . . . . . . . . . . . 52

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FIGURE 10: OPTIONAL TOOL A AND TOOL B - MADE BY THE OPERATOR [Group 1] . . . . . . . . 56

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Commercial 

Airplanes 737

Service Bulletin

ALERT

Summary Number: 737-53A1318

Original Issue: October 31, 2011

ATA System: 5331

SUBJECT: FUSELAGE - Skin - Skin Cracking at the Aft Waste Water Drain Mast - Inspection and

Repair

THIS BULLETIN IS SENT TO THE OPERATORS OF RECORD OF THE AIRPLANES SHOWN IN PARAGRAPH

1.A., EFFECTIVITY. IF AN AIRPLANE HAS BEEN LEASED OR SOLD, SEND THIS SERVICE BULLETIN TO

THE NEW OPERATOR. IF APPLICABLE SPARES HAVE BEEN SOLD, SEND THIS SERVICE BULLETIN TO

THE NEW OWNER.

CONCURRENT REQUIREMENTS

None.

BACKGROUND

This service bulletin is sent to ensure that the aft waste water drain mast is installed correctly. A drain mast that

is not installed correctly can cause cracks in the fuselage skin and the internal support structure. The skin cracks

can not be seen because they are hidden by the drain mast. If cracks in the fuselage skin are not detected and

repaired, they can grow past the frames that are adjacent to the drain mast and reach a critical length. Continued

operation of the airplane with undetected cracks could result in uncontrolled decompression of the airplane.

The drain mast is located between BS 986 - BS 1006 and between Stringer S-24L - S-25L.

In January 2010, one operator reported that the aft drain mast was found loose on a 737-400 airplane with

approximately 30,500 flight cycles. Further investigation revealed the fuselage skin and surrounding back up

structure were cracked. The crack common to the fuselage skin was hidden under the drain mast and was

approximately 8 inches long. The crack was probably caused by incorrect installation of the drain mast.

Accomplishment of the inspections in this service bulletin will make sure that the aft drain mast is installed

correctly and will make sure that cracks under the aft drain mast are detected and repaired before they reach

a critical length.

Boeing Service Related Problem (SRP) 737-SRP-53-0367 is related to this service bulletin.

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737-53A1318

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ACTION

Group 1:

On Group 1 airplanes, get access to the internal support structure for the aft waste water drain mast. Do an

internal detailed inspection of the drain mast support structure for cracks or corrosion. If cracks or corrosion are

found, then contact Boeing for a repair. Inspect the location of the drain mast ground strap. Inspect the washers

under the four bolts that hold the aft drain mast. If the ground strap is installed at an incorrect location, or if

incorrect washers are found, then remove the drain mast and do an HFEC inspection of the skin and support

structure for cracks. Do a detailed inspection of the skin under the drain mast and the support structure for

corrosion. If cracks or corrosion are found, then contact Boeing for a repair.

Group 2:

On Group 2 airplanes, contact Boeing to get instructions for the inspection and repair for this service bulletin,

737-53A1318 Original Issue, and do the work instructed by Boeing.

EFFECTIVITY

737-100/200/200C/300/400/500 Airplanes with the aft waste water drain mast installed. Refer to Paragraph

1.A.1., Airplanes for the list of affected airplanes.

COMPLIANCE

The Federal Aviation Administration (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.

Refer to Paragraph 1.E., Compliance.

INDUSTRY SUPPORT INFORMATION

Boeing warranty remedies are not available for the inspection, configuration changes, and/or repair procedures

given in this service bulletin.

MANPOWER

Refer to Paragraph 1.G., Manpower .

MATERIAL INFORMATION

Operator Supplied Parts/Materials.

Refer to Paragraph 2.A., Material - Price and Availability.

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BLANK PAGE
Commercial 

Airplanes 737

Service Bulletin

ALERT

Number: 737-53A1318

Original Issue: October 31, 2011

ATA System: 5331

SUBJECT: FUSELAGE - Skin - Skin Cracking at the Aft Waste Water Drain Mast - Inspection and

Repair

THIS BULLETIN IS SENT TO THE OPERATORS OF RECORD OF THE AIRPLANES SHOWN IN PARAGRAPH

1.A., EFFECTIVITY. IF AN AIRPLANE HAS BEEN LEASED OR SOLD, SEND THIS SERVICE BULLETIN TO

THE NEW OPERATOR. IF APPLICABLE SPARES HAVE BEEN SOLD, SEND THIS SERVICE BULLETIN TO

THE NEW OWNER.

1. PLANNING INFORMATION

A. Effectivity

1. Airplanes

Refer to Service Bulletin Index D6-19567 Part 3 for Airplane Variable Number, Line Number, and

Serial Number data.

GROUP CONFIGURATION DESCRIPTION

737-200/200C/300/400/500 airplanes with an aft waste water drain

mast installed, excluding line numbers 1-291

1 -

737-100/200 airplanes with an aft waste water drain mast installed,

line numbers 1-291

2 -

Airplane Models:

737-100, 737-200, 737-200C, 737-300, 737-400, 737-500

Variable Number Group

PA001 - PA022 2

PA099 2

PG001 - PG004 2

PG006 - PG019 2

PG022 - PG025 2

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Variable Number Group

PG027 2

PG030 2

PG032 - PG033 2

PG038 - PG040 2

PG044 - PG045 2

PG051 - PG054 2

PG057 2

PG060 - PG063 2

PG065 - PG072 2

PG075 2

PJ003 - PJ009 1

PJ114 - PJ119 1

PJ201 - PJ219 1

PJ301 - PJ302 1

PJ551 - PJ561 1

PJ601 - PJ615 1

PJ811 1

PJ816 - PJ817 1

PK201 - PK202 1

PK281 - PK289 1

PK351 - PK360 1

PK391 1

PK461 - PK469 1

PK495 1

PK501 - PK504 1

PK611 - PK617 1

PK621 - PK637 1

PK671 - PK681 1

PK731 - PK765 1

PK771 - PK779 1

PK801 - PK804 1

PK819 - PK827 1

PK830 1

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Variable Number Group

PK871 - PK874 1

PK901 - PK938 1

PK971 - PK974 1

PL002 - PL024 1

PL081 1

PL221 1

PL401 - PL417 1

PL451 - PL456 1

PL471 1

PL551 - PL562 1

PL624 - PL626 1

PL631 - PL632 1

PL736 - PL747 1

PL762 - PL770 1

PL783 - PL788 1

PM141 - PM142 1

PM171 1

PM251 - PM255 1

PM281 - PM283 1

PM381 - PM399 1

PM401 - PM417 1

PM541 - PM564 1

PN001 - PN002 1

PN021 - PN043 1

PN081 - PN086 1

PN101 - PN117 1

PN451 - PN456 1

PN471 - PN474 1

PN501 - PN502 1

PN521 1

PP001 - PP054 1

PP201 - PP205 1

PP221 1

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Variable Number Group

PP231 - PP243 1

PP281 - PP286 1

PP301 - PP305 1

PP351 - PP353 1

PP384 1

PP391 - PP393 1

PP401 - PP440 1

PP471 - PP475 1

PP501 - PP520 1

PP671 - PP699 1

PP701 - PP733 1

PP801 - PP808 1

PP821 - PP827 1

PP831 - PP848 1

PP851 - PP852 1

PP861 - PP877 1

PP904 - PP936 1

PP946 - PP948 1

PP951 - PP952 1

PP961 - PP967 1

PP981 - PP990 1

PP993 1

PQ001 - PQ016 1

PQ026 - PQ041 1

PQ051 - PQ092 1

PQ101 - PQ199 1

PQ201 - PQ202 1

PQ241 - PQ243 1

PQ251 - PQ267 1

PQ281 - PQ299 1

PQ301 - PQ307 1

PQ331 - PQ332 1

PQ341 - PQ348 1

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Variable Number Group

PQ361 - PQ373 1

PQ391 - PQ395 1

PQ401 - PQ418 1

PQ421 1

PQ431 - PQ438 1

PQ447 - PQ448 1

PQ451 1

PQ454 1

PQ471 - PQ475 1

PQ479 - PQ481 1

PQ486 - PQ487 1

PQ491 - PQ493 1

PQ771 - PQ772 1

PQ791 - PQ793 1

PQ801 - PQ805 1

PQ931 - PQ935 1

PQ951 1

PQ971 - PQ997 1

PR001 - PR017 1

PR021 - PR034 1

PR041 - PR045 1

PR061 - PR072 1

PR077 - PR082 1

PR091 - PR092 1

PR096 1

PR101 1

PR121 - PR122 1

PR131 - PR132 1

PR141 - PR143 1

PR161 - PR172 1

PR181 1

PS601 - PS631 1

PS636 - PS638 1

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Variable Number Group

PS641 - PS644 1

PS669 1

PS691 - PS692 1

PS701 - PS706 1

PS811 1

PS836 - PS837 1

PS841 - PS846 1

PS851 - PS852 1

PS856 1

PS861 - PS863 1

PS866 - PS868 1

PS871 - PS874 1

PS896 - PS897 1

PS956 - PS957 1

PS961 - PS963 1

PS971 - PS978 1

PT001 - PT015 1

PT021 - PT031 1

PT041 - PT064 1

PT101 - PT105 1

PT121 - PT138 1

PT146 - PT148 1

PT161 - PT170 1

PT181 - PT188 1

PT211 - PT220 1

PT295 1

PT331 - PT360 1

PT381 - PT399 1

PT401 - PT438 1

PT501 - PT517 1

PT561 - PT565 1

PT581 - PT586 1

PT611 - PT621 1

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ALERT ALERT
Variable Number Group

PT641 - PT644 1

PT651 - PT656 1

PT671 - PT672 1

PT681 - PT685 1

PT701 - PT703 1

PT716 - PT717 1

PT721 - PT725 1

PT801 - PT834 1

PT851 - PT854 1

PT871 - PT886 1

PT901 - PT930 1

PT971 - PT973 1

PT981 - PT985 1

PT996 1

PU301 1

PV001 - PV055 1

PV201 - PV209 1

PV226 - PV229 1

PV231 - PV237 1

PV271 - PV272 1

PV281 - PV287 1

PV296 1

PV301 - PV302 1

PV351 1

PV356 - PV357 1

PW001 - PW054 1

PW061 - PW068 1

PW072 1

PW086 - PW088 1

PW091 - PW094 1

PW101 - PW102 1

PW106 1

PW111 - PW120 1

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BOEING SERVICE BULLETIN 737-53A1318

ALERT ALERT
Variable Number Group

PW156 - PW157 1

PW161 - PW171 1

PW201 - PW252 1

PW261 - PW268 1

PW271 - PW276 1

PW278 1

PW281 - PW293 1

PW296 1

PW301 - PW327 1

PW401 - PW408 1

PW411 - PW418 1

PW421 - PW424 1

PW431 - PW435 1

PW441 - PW450 1

PW461 - PW467 1

PW501 - PW504 1

PW511 - PW522 1

PW524 - PW550 1

PW556 - PW557 1

PW561 - PW564 1

PW571 - PW576 1

PW591 - PW596 1

PW611 - PW622 1

PW631 - PW637 1

PW661 - PW662 1

PW681 - PW683 1

PW701 - PW702 1

PW711 - PW717 1

PW741 - PW742 1

PW761 1

PW771 1

PW831 1

PW851 - PW856 1

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Variable Number Group

PY056 - PY057 1

PY101 - PY103 1

PY111 - PY113 1

PY151 - PY154 1

PY201 1

PY231 1

PY461 - PY463 1

PY721 1

2. Spares Affected

None.

B. Concurrent Requirements

None.

C. Reason

This service bulletin is sent to ensure that the aft waste water drain mast is installed correctly. A drain

mast that is not installed correctly can cause cracks in the fuselage skin and the internal support

structure. The skin cracks can not be seen because they are hidden by the drain mast. If cracks in the

fuselage skin are not detected and repaired, they can grow past the frames that are adjacent to the

drain mast and reach a critical length. Continued operation of the airplane with undetected cracks could

result in uncontrolled decompression of the airplane.

The drain mast is located between BS 986 - BS 1006 and between Stringer S-24L - S-25L.

In January 2010, one operator reported that the aft drain mast was found loose on a 737-400 airplane

with approximately 30,500 flight cycles. Further investigation revealed the fuselage skin and surrounding

back up structure were cracked. The crack common to the fuselage skin was hidden under the drain

mast and was approximately 8 inches long. The crack was probably caused by incorrect installation

of the drain mast.

Accomplishment of the inspections in this service bulletin will make sure that the aft drain mast is

installed correctly and will make sure that cracks under the aft drain mast are detected and repaired

before they reach a critical length.

Boeing Service Related Problem (SRP) 737-SRP-53-0367 is related to this service bulletin.

BOEING PROPRIETARY -

Copyright © Unpublished Work - See page 1 for details.

Original Issue: October 31, 2011

737-53A1318

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BOEING SERVICE BULLETIN 737-53A1318

ALERT ALERT
D. Description

Group 1:

On Group 1 airplanes, get access to the internal support structure for the aft waste water drain mast.

Do an internal detailed inspection of the drain mast support structure for cracks or corrosion. If cracks

or corrosion are found, then contact Boeing for a repair. Inspect the location of the drain mast ground

strap. Inspect the washers under the four bolts that hold the aft drain mast. If the ground strap is installed

at an incorrect location, or if incorrect washers are found, then remove the drain mast and do an HFEC

inspection of the skin and support structure for cracks. Do a detailed inspection of the skin under the

drain mast and the support structure for corrosion. If cracks or corrosion are found, then contact Boeing

for a repair.

Group 2:

On Group 2 airplanes, contact Boeing to get instructions for the inspection and repair for this service

bulletin, 737-53A1318 Original Issue, and do the work instructed by Boeing.

The work in this service bulletin is done in the maintenance zone(s) given below.

Group 1:

Affected Maintenance Zones

Model Zone

737-200, 737-200C 2-20

Group 1:

Affected Maintenance Zones

Model Zone

737-300, 737-400, 737-500 220

Group 2:

Affected Maintenance Zones

Model Zone

737-100, 737-200 2-20

E. Compliance

The Federal Aviation Administration (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.

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BOEING SERVICE BULLETIN 737-53A1318

ALERT ALERT
Group 1:

Table 1: Aft Waste Water Drain Mast Inspection and Repair on Group 1 Airplanes

Repeat Interval

(Not to Exceed)

Compliance Time (Whichever

Occurs Later )

Condition Action

Within 4,500 None

flight cycles after the original

issue date of

this Service Bulletin.

Before 25,000

total airplane

flight cycles.

Do a detailed inspection of

the channel and the fillers

for cracks and signs of corrosion in accordance with Accomplishment Instruction

3.B.1.c.

737-200/200C/300/400/500

airplanes with an aft waste

water drain mast installed,

excluding line numbers 1-

291

Within 4,500 None

flight cycles after the original

issue date of

this Service Bulletin.

Before 25,000

total airplane

flight cycles.

Inspect the bonding strap for

the correct location in accordance with Accomplishment

Instruction 3.B.1.d. If an incorrect installation is found,

then remove the drain mast

and do an HFEC and detailed inspection of skin,

channel, and fillers for

cracks and signs of corrosion in accordance with Accomplishment Instruction

3.B.1.d

Within 4,500 None

flight cycles after the original

issue date of

this Service Bulletin.

Before 25,000

total airplane

flight cycles.

Measure the diameter of the

washers under the drain

mast bolts in accordance

with Accomplishment Instruction 3.B.1.e. If an incorrect

installation is found, then remove the drain mast and do

an HFEC and detailed inspection of skin, channel,

and fillers for cracks and

signs of corrosion in accordance with Accomplishment

Instruction 3.B.1.e.

Within 4,500 None

flight cycles after the original

issue date of

this Service Bulletin.

Before 25,000

total airplane

flight cycles.

Measure the thickness of the

washers under the drain

mast bolts in accordance

with Accomplishment Instruction 3.B.1.f. If an incorrect

installation is found, then remove the drain mast and do

an HFEC and detailed inspection of skin, channel,

and fillers for cracks and

signs of corrosion in accordance with Accomplishment

Instruction 3.B.1.f.

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Group 1:

Table 1: Aft Waste Water Drain Mast Inspection and Repair on Group 1 Airplanes

Repeat Interval

(Not to Exceed)

Compliance Time (Whichever

Occurs Later )

Condition Action

Contact Boeing to get instruc- Before further flight None

tions for the repair for this

service bulletin, 737-

53A1318 Original Issue, and

do the work instructed by

Boeing.

A crack or sign of corrosion

is found in the the skin, the

channel, or the fillers.

Group 2:

On Group 2 airplanes, contact Boeing to get instructions for the inspection and repair for this service

bulletin, 737-53A1318 Original Issue, and do the work instructed by Boeing before further flight.

F. Approval

This service bulletin was examined by the Federal Aviation Administration (FAA). The changes 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 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. Manpower

The table below shows an estimate of the task hours necessary to do this service bulletin 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 work

• Time to inspect the work

• Time to cure the materials

• Time to make the parts

• Time to find the tools.

Task Number of Persons Task Hours Elapsed Hours

Open Access (Open 1 0.25 0.25

Circuit Breaker)

FIGURE 1 - Open 1 0.55 0.55

Access

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Task Number of Persons Task Hours Elapsed Hours

FIGURE 2 - Detailed 1 1.00 1.00

Inspection

FIGURE 3 - Inspect 1 0.10 0.10

Bonding Strap

FIGURE 4 - Inspect 1 0.15 0.15

Washer Diameter

FIGURE 5 - Inspect 1 0.75 0.75

Washer Thickness,

Instrument Method

FIGURE 6 - Inspect 1 0.20 0.20

Washer Thickness,

Tool Method

FIGURE 7 - Remove 1 0.75 0.75

Drain Mast (a)

FIGURE 8 - HFEC 1 2.00 2.00

and Detailed Inspection (a)

FIGURE 9 - Install 1 1.50 1.50

Drain Mast (a)

FIGURE 10 - Make (b) (b) (b)

Tool

Close Access 1 0.80 0.80

TOTAL FOR EACH AIRPLANE 3.60 3.60

(If Measuring Thickness of Washers by

Instrument Method) (a)

TOTAL FOR EACH AIRPLANE 3.05 3.05

(If Measuring Thickness of Washers by

Optional Tool Method) (a)

(a) The totals given do not include estimates for Figures 7, 8 and 9. If it is necessary to do Figures 7, 8 and 9, then you must add estimates for Figures 7, 8,

and 9 to the totals given. Paragraph 3.B. tells you when it is necessary to do

Figures 7, 8 and 9.

(b) No manpower estimate is given. Time to make tools is considered lost time

in Boeing manpower estimates.

H. Weight and Balance Changes

None.

I. Electrical Load Data

Not applicable.

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J. References

1. Existing Data

a. Service Related Problem (SRP) 737-SRP-53-0367

b. Boeing Service Letter 737-SL-51-042

c. Service Bulletin Index D6-19567

d. Standard Overhaul Practices Manual (SOPM) 20-11-03, 20-41-02, 20-41-05, 20-43-03,

20-50-01, 20-50-19

e. Standard Wiring Practices Manual (SWPM) 20-10-11, 20-10-12, 20-10-19, 20-20-00, 20-20-10

f. 737 Non-Destructive Testing (NDT) Manual Part 6, 51-00-00, Figure 4, Part 6, 51-00-00,

Figure 16, Part 6, 51-00-00, Figure 23

g. 737-100/200 Aircraft Maintenance Manual (AMM) 30-71-0, 51-31-0

h. 737-300/400/500 Aircraft Maintenance Manual (AMM) 30-71-00, 51-31-00

2. Data supplied with this Service Bulletin

None.

3. Installation Drawings Used in the Preparation of this Service Bulletin

Drawing Number Title

65-55843 Aft Waste Water Drain Mast Support Installation

65-55765 Aft Waste Water Drain Mast Installation

These drawings were used to prepare this service bulletin. These drawings are not necessary to

make the specified changes, and are not supplied with this service bulletin. These drawings may

not be applicable to all airplane configurations or operators.

K. Publications Affected

1. Publications:

Publication Chapter-Section

737 Aircraft Maintenance Manual 38-31

737 Illustrated Parts Catalog 38-31

2. Damage Tolerance Based Structural Inspections:

Boeing has evaluated the repairs and/or 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 but no new DTIs are necessary.

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L. Interchangeability and Intermixability of Parts

Accomplishment of this service bulletin does not affect interchangeability or intermixability of parts.

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ALERT ALERT

BLANK PAGE
2. MATERIAL INFORMATION

A. Material - Price and Availability

The operator can supply the parts and materials shown in Paragraph 2.C., Parts Necessary for Each

Airplane. As an alternative, operators can purchase the parts from Boeing Spares. This service bulletin

does not show the Boeing price and supply data.

B. Industry Support Information

Boeing warranty remedies are not available for the inspection, configuration changes, and/or repair

procedures given in this service bulletin.

C. Parts Necessary For Each Airplane

1. Kits/Parts

None.

2. Parts and Materials Supplied by the Operator

Part Number / Specification QTY Name Notes

BACB30LM4-4 4 Bolt (a)

NAS1149D0416H 4 Washer (a)

NAS1523C4R 4 Seal Washer (a)

Type 2, Class A 5 Oz Chemical Conversion Coating (a) (b)

BMS 10-11, Type I 5 Oz Primer (a) (c)

BMS 5-95, Type 1, Class B-1/2 or 10 Oz Sealant (a) (c)

Class B-2

BMS 3-29 15 Oz Corrosion Inhibiting Compound (c)

(a) This part or material is necessary only if you do Figure 9. Paragraph 3.B. tells you when it is necessary

to do Figure 9.

(b) Refer to SOPM 20-43-03 for material sources.

(c) See the Qualified Products List at the end of the Boeing Material Specification (BMS) for supplier data.

3. Parts Modified and Reidentified

None

4. Parts Removed and Not Replaced

None

D. Parts Necessary to Change Spares

None

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E. Special Tooling - Price and Availability

The operator can supply the tools shown in Paragraph 2.F., Special Tooling Necessary to do this

Service Bulletin. Tool price and supply data are not given.

F. Special Tooling Necessary to do this Service Bulletin

The operator can make optional Tool A and Tool B in accordance with Figure 10. Use Tool A and Tool

B as an optional method of measuring the thickness of the washers under the drain mast bolts in

accordance with Figure 6. The operator can do the requirements of this service bulletin without Tool

A and Tool B by measuring the thickness of the washers under the drain mast bolts in accordance with

Figure 5.

Maintenance and overhaul tools in the manuals given in Paragraph 1.J., References, can be necessary.

Examine operator tool supply to make sure all necessary tools are available.

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ALERT ALERT
3. ACCOMPLISHMENT INSTRUCTIONS

A. GENERAL INFORMATION

CAUTION: KEEP THE WORK AREA, WIRES AND ELECTRICAL BUNDLES CLEAN OF METAL

PARTICLES OR CONTAMINATION WHEN YOU USE TOOLS. UNWANTED MATERIAL,

METAL PARTICLES OR CONTAMINATION CAUGHT IN WIRE BUNDLES CAN CAUSE

DAMAGE TO THE BUNDLES. DAMAGED WIRE BUNDLES CAN CAUSE SPARKS OR

OTHER ELECTRICAL DAMAGE.

NOTE: 1. Manual titles are referred to by acronyms. Refer to Paragraph 1.J., References, for

definition of the acronyms.

2. Obey all of the warnings and cautions given in the specified manual sections.

3. Unless shown differently, these dimensions and tolerances are used:

– Linear dimensions are in inches

– Tolerance on linear dimensions, other than rivet and bolt edge margins, is plus

or minus 0.03 inch

– Tolerance on rivet and bolt edge margin is plus or minus 0.05 inch

– Angular tolerance is plus or minus 2 degrees

– Hole dimensions for standard solid rivets and fasteners are in Structural Repair

Manual (SRM) Chapter 51

4. Use the approved fastener and process material substitutions in accordance with

SRM Chapter 51.

5. Refer to the SWPM 20-10-11 and SWPM 20-10-12 for the wire installation procedures,

and SWPM 20-10-19 for the wire separation requirements, as accepted procedures.

6. 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.

7. 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 Boeing document

must be used.

8. Boeing Service Letter 737-SL-51-042, Damage Reporting and Repair Plan/Design

Guidelines, is an acceptable procedure to request information from Boeing for

additional structural repair instructions. The Service Letter describes what information

must be provided to Boeing before a structural repair can be provided.

9. The instructions in Paragraph 3.B., Work Instructions and the figures can include

operation of tools or test equipment. Boeing Engineering Tool Drawings, the Illustrated

Tool and Equipment Manual, and the Special Tool and Ground Handling Drawing

Index contain data on versions of the tools or test equipment that you can use. It is

permitted to use replaced tools. It is not permitted to use superseded tools.

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10. If it is necessary to remove more parts for access, you can remove those parts. If

you can get access without removing identified parts, it is not necessary to remove

all of the identified parts. Jacking and shoring limitations must be observed.

11. Where the work instructions include installation of a kept part, a new or serviceable

part with the same part number can be installed as an alternative to the kept part.

12. This service bulletin includes functional test procedures for the systems changed by

this service bulletin. More functional tests can possibly be necessary in accordance

with standard maintenance practices because of interruption to other airplane systems.

B. WORK INSTRUCTIONS

1. Group 1:

Work Instructions for Group 1 airplanes.

a. Do these Work Instructions at the times given in Paragraph 1.E Compliance.

b. Get access to the work area.

(1) Open the DRAIN MAST HEATER circuit breakers on the P18 panel. Attach

DO-NOT-CLOSE tags.

(2) Get access to the aft waste water drain mast support structure in accordance with Figure

1.

c. Do a detailed inspection of the channel and the fillers for cracks and signs of corrosion adjacent

to the drain mast bolts in accordance with Figure 2.

(1) If there is no crack and no sign of corrosion, then do Paragraph 3.B.1.d.

(2) If there is a crack or sign of corrosion, then contact Boeing for a repair. Refer to Boeing

Service Letter 737-SL-51-042 as an accepted procedure.

d. Inspect the bonding strap for the correct location in accordance with Figure 3.

(1) If the bonding strap is installed at the location in accordance with Figure 3, then do

Paragraph 3.B.1.e.

(2) If the bonding strap is not installed at the location in accordance with Figure 3, then you

you have an incorrect installation. Remove the drain mast in accordance with Figure 7.

Do an HFEC inspection of the skin, the channel, and the fillers for cracks that start at the

drain mast bolt holes, in accordance with Figure 8. Do a detailed inspection of the skin,

the channel, and the fillers for signs of corrosion adjacent to the drain mast bolt holes, in

accordance with Figure 8.

(3) If there is no crack and no sign of corrosion, then install the drain mast in accordance

with Figure 9 and do Paragraph 3.B.1.g.

(4) If there is a crack or sign of corrosion, then contact Boeing for a repair. Refer to Boeing

Service Letter 737-SL-51-042 as an accepted procedure.

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e. Measure the diameter of the washers under the drain mast bolts in accordance with Figure

4.

(1) If the diameter of all the washers measures within the range in accordance with Figure

4, then do Paragraph 3.B.1.f.

(2) If the diameter of any washer does not measure within the range in accordance with

Figure 4, or if no washers are installed, then you have an incorrect installation. Remove

the drain mast in accordance with Figure 7. Do an HFEC inspection of the skin, the

channel, and the fillers for cracks that start at the drain mast bolt holes, in accordance

with Figure 8. Do a detailed inspection of the skin, the channel, and the fillers for signs

of corrosion adjacent to the drain mast bolt holes, in accordance with Figure 8.

(3) If there is no crack and no sign of corrosion, then install the drain mast in accordance

with Figure 9 and do Paragraph 3.B.1.g.

(4) If there is a crack or sign of corrosion, then contact Boeing for a repair. Refer to Boeing

Service Letter 737-SL-51-042 as an accepted procedure.

f. Measure the thickness of the washers under the drain mast bolts in accordance with Figure

5. As an option, you can make Tool A and Tool B in accordance with Figure 10, and measure

the thickness of the washers under the drain mast bolts in accordance with Figure 6.

(1) If the thickness of the washers measures within range in accordance with Figure 5 or

Figure 6, then do Paragraph 3.B.1.g.

(2) If the thickness of the washers does not measure within the range in accordance with

Figure 5 or Figure 6, then you have an incorrect installation. Remove the drain mast in

accordance with Figure 7. Do an HFEC inspection of the skin, the channel, and the fillers

for cracks that start at the drain mast bolt holes, in accordance with Figure 8. Do a detailed

inspection of the skin, the channel, and the fillers for signs of corrosion adjacent to the

drain mast bolt holes, in accordance with Figure 8.

(3) If there is no crack and no sign of corrosion, then install the drain mast in accordance

with Figure 9 and do Paragraph 3.B.1.g.

(4) If there is a crack or sign of corrosion, then contact Boeing for a repair. Refer to Boeing

Service Letter 737-SL-51-042 as an accepted procedure.

g. Close access to the work area.

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(1) Apply Corrosion Inhibiting Compound BMS 3-29 to the area where corrosion inhibiting

compound was removed for inspection. Refer to SOPM 20-41-05 as an accepted

procedure.

(2) Install the kept insulation that was removed for access.

(3) Install the kept aft cargo compartment access panel that was removed for access.

(4) Remove the DO-NOT-CLOSE tags and close the DRAIN MAST HEATER circuit breakers

on the P18 panel.

(5) Return the airplane to a serviceable condition.

2. Group 2:

Work Instructions for Group 2 airplanes.

a. Do these Work Instructions at the times given in Paragraph 1.E Compliance.

b. On Group 2 airplanes, contact Boeing to get instructions for the inspection and repair for this

service bulletin, 737-53A1318 Original Issue, and do the work instructed by Boeing.

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ALERT ALERT
This Figure applies only to: Group 1.

FIGURE 1: GET ACCESS TO THE DRAIN MAST SUPPORT STRUCTURE

(SHEET 1 OF 3)

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FIGURE 1: GET ACCESS TO THE DRAIN MAST SUPPORT STRUCTURE

(SHEET 2 OF 3)

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ALERT ALERT
The step numbers shown below agree with the numbers shown in the circle symbols in the figure.

STEP TASK NAME MORE DATA

Remove and keep the access panel from the aft bulkhead in

the aft cargo compartment.

Remove / Access Panel

Keep

1

Remove the insulation from the drain mast support structure.

Keep the insulation. Make sure that you can see the four

drain mast bolts. Make sure you can see the bonding strap.

(a)

Remove / Insulation

Keep

2

(a) The drain mast support structure is located 4.5 feet behind the bulkhead between BS 986 - BS 1006 and

between Stringer S-24L - S-25L.

FIGURE 1: GET ACCESS TO THE DRAIN MAST SUPPORT STRUCTURE

(SHEET 3 OF 3)

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This Figure applies only to: Group 1.

FIGURE 2: DO A DETAILED INSPECTION OF THE CHANNEL AND THE FILLERS

(SHEET 1 OF 2)

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ALERT ALERT
The step numbers shown below agree with the numbers shown in the circle symbols in the figure.

STEP TASK NAME MORE DATA

Clean the channel and the fillers for inspection. The inspection

area must be clean of dirt, grease, corrosion inhibiting compound, or other substances that prevent a detailed inspection

of the structure. Make sure you only use approved compound

removal tools. Refer to 737-100/200 AMM 51-31-0 or 737-

300/400/500 AMM 51-31-00 as an accepted procedure.

1 Clean Channel / Filler

Do an internal detailed inspection of the channel and the

fillers for cracks and signs of corrosion adjacent to the drain

mast bolts.

2 Inspect Channel / Filler

FIGURE 2: DO A DETAILED INSPECTION OF THE CHANNEL AND THE FILLERS

(SHEET 2 OF 2)

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This Figure applies only to: Group 1.

FIGURE 3: INSPECT THE BONDING STRAP LOCATION

(SHEET 1 OF 2)

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The step numbers shown below agree with the numbers shown in the circle symbols in the figure.

STEP TASK NAME MORE DATA

Make sure that the bonding strap is installed on the forward

drain mast bolt. (a)

1 Inspect Bonding Strap

(a) If the bonding strap is installed on a drain mast bolt that is not the forward drain mast bolt, then you have

an incorrect installation.

FIGURE 3: INSPECT THE BONDING STRAP LOCATION

(SHEET 2 OF 2)

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This Figure applies only to: Group 1.

FIGURE 4: MEASURE THE DIAMETER OF THE WASHERS UNDER THE DRAIN MAST BOLTS

(SHEET 1 OF 2)

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The step numbers shown below agree with the numbers shown in the circle symbols in the figure.

STEP TASK NAME QTY MORE DATA

Make sure that the diameter of all the washers under the drain mast bolt measures less

than 0.55 inch. (a) (b) (c)

4 Bolt Locations1 Measure Diameter of Washers

(a) One or two washers may be installed.

(b) If the diameter of any washer measures larger than 0.55 inch, then you have an incorrect installation.

(c) If no washers are installed, then you have an incorrect installation.

FIGURE 4: MEASURE THE DIAMETER OF THE WASHERS UNDER THE DRAIN MAST BOLTS

(SHEET 2 OF 2)

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This Figure applies only to: Group 1.

FIGURE 5: MEASURE THE THICKNESS OF THE WASHERS UNDER THE DRAIN MAST BOLTS -

INSTRUMENT METHOD

(SHEET 1 OF 3)

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FIGURE 5: MEASURE THE THICKNESS OF THE WASHERS UNDER THE DRAIN MAST BOLTS -

INSTRUMENT METHOD

(SHEET 2 OF 3)

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The step numbers shown below agree with the numbers shown in the circle symbols in the figure.

STEP TASK NAME QTY MORE DATA

Make sure that the thickness of the washers

under the drain mast bolt measures 0.057 -

0.074 inch. (a) (b) (c)

3 Bolt Locations1 Measure Thickness of Washers

Make sure that the thickness of the washers

and the bonding strap lug under the drain

mast bolt measures 0.086 - 0.109 inch. (a)

(b) (c)

Thickness of Washers 1 Bolt Location

and Bonding Strap Lug

2 Measure

(a) Measure from the upper surface of the filler to the upper surface of the top washer. Use an instrument

that is capable of measuring the geometric step to an accuracy of +/- 0.001 inch.

(b) One or two washers may be installed. If one washer is installed, then the thickness must measure within

the minimum and maximum range given.

(c) If the thickness of the washers or the thickness of the washers and bonding strap do not measure within

the minimum and maximum range given, then you have an incorrect installation.

FIGURE 5: MEASURE THE THICKNESS OF THE WASHERS UNDER THE DRAIN MAST BOLTS -

INSTRUMENT METHOD

(SHEET 3 OF 3)

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This Figure applies only to: Group 1.

FIGURE 6: MEASURE THE THICKNESS OF THE WASHERS UNDER THE DRAIN MAST BOLTS - OPTIONAL

TOOL METHOD

(SHEET 1 OF 4)

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FIGURE 6: MEASURE THE THICKNESS OF THE WASHERS UNDER THE DRAIN MAST BOLTS - OPTIONAL

TOOL METHOD

(SHEET 2 OF 4)

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FIGURE 6: MEASURE THE THICKNESS OF THE WASHERS UNDER THE DRAIN MAST BOLTS - OPTIONAL

TOOL METHOD

(SHEET 3 OF 4)

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The step numbers shown below agree with the numbers shown in the circle symbols in the figure.

STEP TASK NAME QTY MORE DATA

Make sure that the thickness of the washers under

the drain mast bolt is within the maximum limit of

0.074 inch. Do the measurement with the TOOL A

MAXIMUM MEASUREMENT (GO GAUGE). If Tool

A slides over the top surface of the washer, then the

thickness of the washers is within the maximum

limit. (a) (b) (c)

3 Bolt LocationsThickness of

Washers Compared to Maximum Limit

1 Measure

Make sure that the thickness of the washers under

the drain mast bolt is within the minimum limit of

0.057 inch. Do the measurement with the TOOL A

MINIMUM MEASUREMENT (NO-GO GAUGE). If

Tool A does not slide over the top surface of the

washer, then the thickness of the washers is within

the minimum limit. (a) (b) (d)

3 Bolt LocationsThickness of

Washers Compared to Minimum

Limit

2 Measure

Make sure that the thickness of the washers and

the bonding strap lug under the drain mast bolt is

within the maximum limit of 0.109 inch. Do the

measurement with the TOOL B MAXIMUM MEASUREMENT (GO GAUGE). If the Tool B slides over

the top surface of the washer, then the thickness of

the washers is within the maximum limit. (a) (b) (c)

Thickness of 1 Bolt Location

Washers and

Bonding Strap

Lug Compared to

Maximum Limit

3 Measure

Make sure that the thickness of the washers and

the bonding strap under the drain mast bolt is within

the minimum limit of 0.086 inch. Do the measurement with the TOOL B MINIMUM MEASUREMENT

(NO-GO GAUGE). If Tool B does not slide over the

top surface of the washer, then the thickness of the

washers is within the minimum limit. (a) (b) (d)

Thickness of 1 Bolt Location

Washers and

Bonding Strap

Lug Compared to

Minimum Limit

4 Measure

(a) Measure from the upper surface of the filler to the upper surface of the top washer. Put the end of the tool

flat on the filler. Slide the tool to a location where the washer protrudes past the bolt head. If necessary,

use 15X magnification to visually verify if the tool does, or does not, slide over the washers.

(b) One or two washers may be installed. If one washer is installed, then the thickness must measure within

the minimum and maximum range given.

(c) If the MAXIMUM MEASUREMENT (GO GAUGE) end of the tool does not slide over the top surface of

the washer, then you have an incorrect installation.

(d) If the MINIMUM MEASUREMENT (NO-GO GAUGE) end of the tool does slide over the top surface of the

washer, then you have an incorrect installation.

FIGURE 6: MEASURE THE THICKNESS OF THE WASHERS UNDER THE DRAIN MAST BOLTS - OPTIONAL

TOOL METHOD

(SHEET 4 OF 4)

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ALERT ALERT
This Figure applies only to: Group 1.

FIGURE 7: REMOVE THE DRAIN MAST

(SHEET 1 OF 2)

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ALERT ALERT
CAUTION: WHEN YOU REMOVE THE FASTENERS THAT HOLD THE DRAIN MAST, ASK ANOTHER

PERSON TO HOLD THE DRAIN MAST FROM THE OUTSIDE OF THE AIRPLANE. IF THE

DRAIN MAST FALLS, DAMAGE CAN OCCUR.

CAUTION: OBEY THE INSTRUCTIONS IN THE STEPS TO REMOVE THE SEALANT FROM THE SKIN. IF

YOU DO NOT OBEY THE INSTRUCTIONS, DAMAGE TO THE AIRPLANE SURFACE CAN

OCCUR.

The step numbers shown below agree with the numbers shown in the circle symbols in the figure.

STEP TASK NAME SPEC MORE DATA

Loosen the clamp and disconnect the drain mast

tube. Make sure that you do not damage the drain

mast tube when you disconnect it. Keep the drain

mast tube and clamp.

Drain Mast -

Tube / Clamp

Disconnect

/ Keep

1

Disconnect the drain mast electrical wires at the

splices. Keep the drain mast wires. (a)

Drain Mast -

Wires

Disconnect

/ Keep

2

Remove and discard the drain mast bolts and washers. Make sure that another person holds the drain

mast from the outside of the airplane so that the drain

mast does not fall. Make sure you do not damage

the bonding strap when you remove the bolt. Keep

the bonding strap. (a)

Bolts / Wash- -

ers

Remove /

Discard

3

Remove / Drain Mast - Remove and keep the drain mast.

Keep

4

Remove the aerodynamic smoother and faying surface sealant from the skin and the drain mast. Make

sure you do not damage the skin when you remove

the sealant. Make sure you only use approved

sealant removal tools. Refer to 737-100/200 AMM

51-31-0 or 737-300/400/500 AMM 51-31-00 as an

accepted procedure.

737-100/200 AMM

51-31-0 or 737-

300/400/500 AMM

51-31-00

5 Remove Sealant

(a) The drain mast wires and the bonding strap are connected to the drain mast. They are removed from the

airplane when the drain mast is removed.

FIGURE 7: REMOVE THE DRAIN MAST

(SHEET 2 OF 2)

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ALERT ALERT
This Figure applies only to: Group 1.

FIGURE 8: DO AN HFEC AND DETAILED INSPECTION OF THE SKIN, THE CHANNEL, AND THE FILLERS

(SHEET 1 OF 3)

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ALERT ALERT
FIGURE 8: DO AN HFEC AND DETAILED INSPECTION OF THE SKIN, THE CHANNEL, AND THE FILLERS

(SHEET 2 OF 3)

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BOEING SERVICE BULLETIN 737-53A1318

ALERT ALERT
The step numbers shown below agree with the numbers shown in the circle symbols in the figure.

STEP TASK NAME QTY SPEC MORE DATA

Do an open hole HFEC inspection of the

drain mast bolt holes in accordance with

737 NDT Part 6, 51-00-00, Figure 16.

737 NDT Part 6,

51-00-00, Figure

16

4 Bolt Hole Locations1 Inspect Bolt Holes

Do an external HFEC inspection of the

skin for cracks that start at the drain

mast bolt holes in accordance with 737

NDT Part 6, 51-00-00, Figure 4 or 737

NDT Part 6, 51-00-00, Figure 23. Inspect

approximately a 0.125 inch zone around

each bolt hole.

737 NDT Part 6,

51-00-00, Figure 4

/ 737 NDT Part 6,

51-00-00, Figure

23

2 Inspect Skin -

Do an external detailed inspection of the

skin for signs of corrosion adjacent to

the drain mast bolt holes.

3 Inspect Skin - -

Do an internal HFEC inspection of the

channel and the fillers for cracks that

start at the drain mast bolt holes in accordance with 737 NDT Part 6, 51-00-00,

Figure 4 or 737 NDT Part 6, 51-00-00,

Figure 23. Inspect approximately a 0.125

inch zone around each bolt hole.

737 NDT Part 6,

51-00-00, Figure 4

/ 737 NDT Part 6,

51-00-00, Figure

23

Channel / -

Fillers

4 Inspect

Do an internal detailed inspection of the

channel and the fillers for signs of corrosion adjacent to the drain mast bolt

holes.

Channel / - -

Fillers

5 Inspect

FIGURE 8: DO AN HFEC AND DETAILED INSPECTION OF THE SKIN, THE CHANNEL, AND THE FILLERS

(SHEET 3 OF 3)

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BOEING SERVICE BULLETIN 737-53A1318

ALERT ALERT
This Figure applies only to: Group 1.

FIGURE 9: INSTALL THE DRAIN MAST

(SHEET 1 OF 4)

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ALERT ALERT
FIGURE 9: INSTALL THE DRAIN MAST

(SHEET 2 OF 4)

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BOEING SERVICE BULLETIN 737-53A1318

ALERT ALERT
CAUTION: OBEY THE INSTRUCTIONS IN THE STEPS TO APPLY THE SEALANT. IF YOU DO NOT OBEY

THE INSTRUCTIONS, DAMAGE TO THE AIRPLANE SURFACE CAN OCCUR.

The step numbers shown below agree with the numbers shown in the circle symbols in the figure.

PART NUMBER / MORE DATA

SPEC

STEP TASK NAME

Apply sealant BMS 5-95, Type 1, Class B1/2 or Class B-2 to the drain mast and the

airplane faying surface. Make sure you do

not damage the skin when you apply the

sealant. Refer to SOPM 20-50-19, 737-

100/200 AMM 51-31-0 and 737-300/400/500

AMM 51-31-00 as accepted procedures.

BMS 5-95, Type 1,

Class B-1/2 or Class

B-2 / SOPM 20-50-

19, 737-100/200

AMM 51-31-0, 737-

300/400/500 AMM

51-31-00

1 Seal Drain Mast

Install / Drain Mast - Put the kept drain mast in position.

Kept

2

Install new drain mast bolts and washers in

accordance with Table 1. Make sure that you

install the kept bonding strap at Bolt Location

4 in accordance with Table 1.

Use the part numbers and specifications in accordance

with Table 1

Bolts / Washers / Bonding

Strap

Install /

New / Kept

3

Make a fillet seal (aerodynamic smoother)

around the drain mast with sealant BMS 5-

95, Type 1, Class B-1/2 or Class B-2. Make

sure you do not damage the skin when you

apply the sealant. Refer to SOPM 20-50-19,

737-100/200 AMM 51-31-0 and 737-

300/400/500 AMM 51-31-00 as accepted

procedures.

BMS 5-95, Type 1,

Class B-1/2 or Class

B-2 / SOPM 20-50-

19, 737-100/200

AMM 51-31-0, 737-

300/400/500 AMM

51-31-00

4 Seal Drain Mast

Connect the kept drain mast tube to the fitting on the drain mast with the kept clamp.Drain Mast -

Tube / Clamp

Connect /

Kept

5

Drain Mast - Connect the kept drain mast electrical wires.

Wires

Connect /

Kept

6

Do a check for leaks on the drain mast in

accordance with the instructions that follow:

Plug the drain mast. Let the water run from

the sink of an adjacent lavatory. Check for

leaks at the drain mast tube connection to

the drain mast. Remove the plug from the

drain mast.

Drain Mast / -

Drain Mast

Tube

7 Test

Do a check for heating of the drain mast.

Refer to 737 737-100/200 AMM 30-71-0 and

737-300/400/500 AMM 30-71-00 as accepted procedures.

737-100/200 AMM

30-71-0, 737-

300/400/500 AMM

30-71-00

8 Test Drain Mast

FIGURE 9: INSTALL THE DRAIN MAST

(SHEET 3 OF 4)

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BOEING SERVICE BULLETIN 737-53A1318

ALERT ALERT
Table 1: Installation of the Drain Mast Bolts, Washers, and Bonding Strap

BOLT LOCATION NAME PART NUMBER QTY More Data

Bolt Location 1 Bolt BACB30LM4-4 1 (a) (b)

Washer NAS1149D0416H 1 (b)

Seal Washer NAS1523C4R 1 (b)

Bolt Location 2 Bolt BACB30LM4-4 1 (a) (b)

Washer NAS1149D0416H 1 (b)

Seal Washer NAS1523C4R 1 (b)

Bolt Location 3 Bolt BACB30LM4-4 1 (a) (b)

Washer NAS1149D0416H 1 (b)

Seal Washer NAS1523C4R 1 (b)

Bolt Location 4 Bolt BACB30LM4-4 1 (a) (b) (c) (d) (e)

Washer NAS1149D0416H 1 (b) (c) (d) (e)

Seal Washer NAS1523C4R 1 (b) (c) (d) (e)

Bonding Strap Kept Part 1 (b) (c) (d) (e)

(a) Apply torque to the drain mast bolts in accordance with the instructions that follow: Apply a torque of 8 -

12 inch-pounds to bolt locations 1 and 4. Apply a torque of 8 - 12 inch-pounds to bolt locations 2 and 3.

Apply a torque of 38 - 42 inch-pounds to bolt locations 1 and 4. Apply a torque of 38 - 42 inch-pounds to

bolt locations 2 and 3. Apply a final torque of 78 - 82 inch-pounds to bolt locations 1 and 4. Apply a final

torque of 78 - 82 inch-pounds to bolt locations 2 and 3. Refer to SOPM 20-50-01 as an accepted procedure.

(b) Apply chemical conversion coating Type 2, Class A to the bare surfaces of the washers and bonding strap

lug after you install them. Refer to SOPM 20-43-03 as an accepted procedure. Apply one coat of primer

BMS 10-11, Type I to the drain mast bolts, washers, and bonding strap lug. Refer to SOPM 20-41-02 as

an accepted procedure.

(c) This is the forward drain mast bolt location.

(d) These are electrical bonding parts. Clean the drain mast bolt, the washers, and the bonding strap before

you install them. Refer to SOPM 20-11-03, Cleaning Method CM3, as an accepted procedure. Make sure

the bonding area meets electrical bonding requirements. The resistance between the bonding strap and

the airplane structure must be less than 0.001 ohm. Refer to SWPM 20-20-00 and SWPM 20-20-10 as

accepted procedures.

(e) Apply sealant BMS 5-95, Type 1, Class B-1/2 or B-2 to the drain mast bolt, washers, and bonding strap

lug. This gives corrosion protection at the electrical bonding location. Refer to SOPM 20-50-19, 737-

100/200 AMM 51-31-0 and 737-300/400/500 AMM 51-31-00 as accepted procedures.

FIGURE 9: INSTALL THE DRAIN MAST

(SHEET 4 OF 4)

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ALERT ALERT
This Figure applies only to: Group 1.

FIGURE 10: OPTIONAL TOOL A AND TOOL B - MADE BY THE OPERATOR

(SHEET 1 OF 3)

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ALERT ALERT
FIGURE 10: OPTIONAL TOOL A AND TOOL B - MADE BY THE OPERATOR

(SHEET 2 OF 3)

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BOEING SERVICE BULLETIN 737-53A1318

ALERT ALERT
The step numbers shown below agree with the numbers shown in the circle symbols in the figure.

STEP TASK NAME PART NUMBER MORE DATA

Make Tool A from aluminum. (a) (b) (c) (d)

(e)

Measuring Tool A

Tool, Washers

1 Make

Make Tool B from aluminum. (a) (b) (c) (d)

(e)

Measuring Tool B

Tool, Washers

and Bonding

Strap Lug

2 Make

(a) The operator can supply any aluminum alloy and heat treat to make the tool.

(b) Tolerance for dimensions X.XX is plus or minus 0.03. Tolerance for dimensions X.XXX is plus or

minus 0.001.

(c) Break all sharp edges.

(d) No finish is necessary.

(e) Identify each end of the tool as shown. Any marking method is acceptable.

FIGURE 10: OPTIONAL TOOL A AND TOOL B - MADE BY THE OPERATOR

(SHEET 3 OF 3)

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BOEING SERVICE BULLETIN 737-53A1318

ALERT ALERT