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747-100/200/300/SP

AIRWORTHINESS LIMITATIONS (AWLs) AND

CERTIFICATION MAINTENANCE REQUIREMENTS (CM

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TABLE OF CONTENTS

REVISIONS .......................................................................................................................................................................................LIST OF EFFECTIVE PAGES ...........................................................................................................................................................A. SCOPE..........................................................................................................................................................................................B. CERTIFICATION MAINTENANCE REQUIREMENTS (CMRS) ....................................................................................................

C. AIRWORTHINESS LIMITATIONS – SYSTEMS............................................................................................................................

C.1 FUEL TANK IGNITION PREVENTION ...................................................................................................................................C.2 IMPACT-RESISTANT FUEL TANK ACCESS DOORS ...........................................................................................................

D. LIMIT OF VALIDITY (LOV)............................................................................................................................................................

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REVISIONS

REVISION AND REVISION DESCRIPTION 

October 2002Original Release - Added CMR 25-CMR-01 applicable only to airplanes with any of the following Service Bulletins installed: 747-25-3314, 747-25-3320 or 747-25-3321. This amended type design complies with the new 14 CFR 25.795 and the amended 14 CFR 25.772 as issued under Federal Register Docket No. FAA-2001-11032.

Submitted by:M. Razniewski (Boeing)

Approved by

March 2006Added new fuel system airworthiness limitation which includes inspections and design limitations to satisfy SFAR 88 requirements.

Submitted by:S. A. Pierini (Boeing)

Approved by

May 2006Revised 28-AWL-03 to correct AMM reference. Revised 28-AWL-06 to correct bonding resistance value. Revised 28-AWL-13 to correct bonding resistance value.

Submitted by:S. A. Pierini (Boeing)

Approved byACO)

December 2006Revised CMR (25-CMR-01) interval from 4 years to 6 years to reflect improved reliability data for the Flight Deck Door Strike Assembly.

Submitted by:S. A. Pierini (Boeing)

Approved by

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January 2007Added new center Left/Right wing reserve tank fueling valve CDCCL AWL Number 28-AWL-20. This CDCCL is applicable to airplanes that have incorporated the intent of Service Bulletin 747-28A2291.Added new motor operator valve actuate CDCCL Number 28-AWL-21. This CDCCL is applicable to airplanes that have incorporated the intent of Service Bulletin 747-28A2292.Added new Center Tank Override Fuel Pump Inlet Protection and Power Failed on Protection System Inspection Number 28-AWL-22. This inspection is applicable to airplanes that have incorporated the intent of Service Bulletin 747-28A2288.

Submitted by:S. A. Pierini (Boeing)

Approved byACO)

September 2007Revised Section B. Exceptional Short-Term Extensions, to include revisions to clarify notification requirements surrounding short-term extensions.Revised Section D. Airworthiness Limitations - Systems, to include revisions by replacing “FAA office that is responsible for the airplane model Type Certificate, or applicable regulatory agency” with “FAA Seattle ACO, or applicable regulatory agency”.Revised Section D. Airworthiness Limitations - Systems to include revisions to clarify notification requirements surrounding short-term extensions.Revised the table in Section D. to read " PAGE FORMAT: FUEL SYSTEM AIRWORTHINESS LIMITATIONS "instead of “PAGE FORMAT: AIRWORTHINESS LIMITATIONS SYSTEM”.Revised AWL Number 28-AWL-18 to add Ground Fault Interrupter (GFI) relays to the limitation that restricts resetting of fuel pump circuit breakers.Added AWL Number 28-AWL-23, a yearly check of the Boost Pump GFI, applicable to airplanes that have incorporated Service Bulletin 747-28A2261.

Submitted by: Ted Dewing (Boeing)

Approved by

ACO)

REVISION AND REVISION DESCRIPTION 

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January 2008Revised Exceptional Short-Term Extension guidelines for CMRs to clarify notification requirements for CMR 25-CMR-01.Revised 25-CMR-01 Task Interval from 6 years to 9 years to reflect improved reliability data for the Flight Deck Security Door.

Submitted by: Eugene Lange (Boeing)

Approved by

March 2008Revised 28-AWL-01 to remove 36000FH task interval limitation based upon engineering review and operator maintenance practice and removed body station and buttock line text and replaced with "per AMM 28-11-00".Revised 28-AWL-13 by removing the 36000FH task interval limitation based upon engineering review and operator maintenance practice.Revised 28-AWL-03 to reflect the new maximum loop resistance values associated with the lightning protection of the unpressurized FQIS wire bundle installations so as 

to satisfy the Airworthiness Limitation Instructions required by SFAR 88. Also removed the joint resistance values and 36000FH task interval limitation based upon engineering review and operator maintenance practice.Revised 28-AWL-06 to update the value from 10 milliohms to 1 milliohm to correctly reflect the numerical value given (0.001 ohm (1 milliohm) or less).

Submitted by: John Sabolchy (Boeing)

Approved by(FAA Seattle 

July 2012Added a new Section E. Limit of Validity (LOV) as required by Title 14 Code of Federal Regulations (CFR) Section 26.21 (Amendment 26-6).

Submitted by: Sameera Wijesinghe (Boeing)

S

REVISION AND REVISION DESCRIPTION 

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August 2012Revised the title of Section C from “Page Format: Systems Maintenance Program” to “Page Format: CMRs” and made it a subheading of Section B to be consistent with other CMR documents.Revised Section D to be Section C, added the word "Fuel" to the title, and replaced the "Fuel Systems Airworthiness Limitations" subheading with "Introduction" to be consistent with other CMR documents. Revised the subheading from "Airworthiness Limitations - Fuel System AWLs" to "C.1 AWLs - FUEL TANK IGNITION PREVENTION", making it subheading C.1.Added Section C.2, Impact-Resistant Fuel Tank Access Doors.Revised Section E to become Section D, in order to remain sequential with the heading changes above.

Submitted by: Mark Arnold (Boeing)

S

June 2014Revised Section C to define FAA Oversight Office and replaced all references of "FAA Seattle ACO" with "FAA Oversight Office" throughout the entire section.References to FAA regulations were changed to include "Title 14 CFR §" to accurately reflect FAA regulation citations throughout the document and for consistency.Revised Section C to replace the word "per" with "in accordance with" throughout the entire section. Revised Section C front matter with the following:Deleted first two paragraphs under "Introduction" since they are applicable to 

Section C.1, "AWLs – Fuel Systems Ignition Prevention" only.Added the information on FAA approved Airworthiness Limitations required under Title 14 CFR § 43.16 and § 91.403 to the "Introduction" subparagraph and added clarification that changes to AWL requires approval by the FAA Oversight Office. 

(Continued on next page)

Submitted by:  Cassandra Ho (Boeing)

S

REVISION AND REVISION DESCRIPTION 

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June 2014, ContinuedAdded reference to the SFAR 88 and Title 14 CFR § 25.981 to the CDCCL paragraph under "Introduction" to specify that the CDCCL is required by these regulations. Also, clarified the word "maintenance" to include alterations.Moved the "Regulatory Agency Approval" to after the "Introduction" subparagraph. Provides clarification that the operator not under the FAA jurisdiction should get the deviations from the AWL instructions from their local regulatory authority.Revised "USE OF ALTERNATE TOOLS" to "USE OF ALTERNATE TOOLS OR EQUIVALENT TOOLS, TEST EQUIPMENT OR MATERIALS". Added clarification 

that the use of alternate or equivalent tools, test equipment, or materials that is outlined in AWL and CMM that is cited as "as "in accordance with" and not "refer to" requires FAA Oversight Office approval.Revised the Exceptional Short-Term Extensions subparagraph, changing "fuel system AWL" to "system AWL" to apply the front matter to all AWLs under Section C. Revised "(e.g., a Principal Maintenance Inspector)" to "or a Principal Maintenance 

Inspector" and the Flight Standards Handbook reference from "8300.10" to "8900.1 FSIMS". Removed reference to CDCCL from the "AWL/CDCCL Revision Process" subparagraph.Added "Accomplishment Instructions - General Information" to clarify the use of "in accordance with" and "refer to" verbiage when referencing other Instructions for Continued Airworthiness documents. Added reference to SWPM 20-20 for electrical bonding and grounding requirements.Added new subparagraphs "Definitions” to provide further clarification on 

accomplishment instructions, and "Supporting Documentation” to clarify that strict adherence to the methods, techniques and practices, as prescribed, is required to ensure the ALI or CDCCL is complied with.Revised "Page Format: Fuel System Airworthiness Limitations" to "Page Format: System Airworthiness Limitations" to apply the front mater to all AWLs under Section C.

(Continued on next page)

Continued from previous page Con

REVISION AND REVISION DESCRIPTION 

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June 2014, ContinuedRevised C.1 front matter to clarify that the section is a FAA approved program of scheduled inspections. Added Amendment 25-102 to the Title 14 CFR § 25.981 regulations.Revised AWL 28-AWL-10 to provide clarification when a repair or alteration involving new or altered fuel tank penetrations requires FAA Oversight Office approval and when a repair or alteration does not require additional FAA Oversight Office approval. Added additional notation to require electrical bonding of fitting, brackets, cap sealing fasteners, and/or fillet sealing of component interface to structure.Added 28-AWL-24 for the verification of the conduit liner, Teflon sleeve, and jacketed and shielded wiring is installed when the pump wiring or wiring in the conduit is removed or replaced for 747 that have incorporated SB 747-28A2306.Added 28-AWL-25 for the inspection of Teflon sleeving and clamps around the wire bundle in clamp locations specified in Service Bulletin 747-57A2327.Added 28-AWL-26 for the verification of the Teflon sleeve is installed when the pump wiring or wiring in the conduit is removed or replaced for 747 that have incorporated SB 747-28A2204 but have not incorporated SB 747-28A2306.Added 28-AWL-27 to verify that the Teflon sleeving around the wire bundle in clamp locations specified in Service Bulletin 747-57A2327 is not damaged.Added 28-AWL-28 for the inspection of the cap seals and fillet seals when maintenance is performed in the fuel tanks.Revised AWL 57-AWL-01 to add AMM 28-11-02 reference.

Continued from previous page Con

REVISION AND REVISION DESCRIPTION 

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A. SCOPE

The scheduled maintenance requirements described in this section result from airplane certification activities with the U.S. Fed

(FAA). Accordingly, this FAA approved Certification Maintenance Requirements (CMRs) document is cross-referenced in the M

Type Certificate Data Sheet. This document satisfies the requirements of Title 14 Code of Federal Regulations (CFR) § 25.571Circular (AC) 25-19 as the controlling document for all 747 CMRs. These maintenance actions are mandatory. 

Where used in this document, the term “FAA Oversight Office” is defined as the FAA office that currently has oversight respons

of the Boeing model 747-100/200/300/SP. At the time of publication, the FAA office with oversight responsibility for the type cer

300/SP is the FAA Boeing Aviation Safety Oversight Office (BASOO).

B. CERTIFICATION MAINTENANCE REQUIREMENTS (CMRs)

CMR DEFINITIONAs defined by AC 25-19, a CMR is a required periodic task, established during the design certification of the airplane as an ope

certificate. CMRs usually result from a formal, numerical analysis conducted to show compliance with catastrophic and hazardAdditional notes concerning the definition of CMRs:1. A CMR is intended to detect safety-significant latent (hidden) failures that would, in combination with one or more specific f

hazardous or catastrophic failure condition.

2. It is important to note that CMRs are derived from a fundamentally different analysis process than the maintenance tasks a

the Maintenance Steering Group (MSG-3) Analysis associated with Maintenance Review Board (MRB) activities. MSG-3 A

maintenance tasks that are performed for safety, operational, or economic reasons, involving both preventative maintenance before failure occurs (and are intended to prevent failures), as well as failure-finding tasks. CMRs, on the other hand, are ty

and exist solely to limit the exposure to otherwise hidden failures. Nevertheless, use of potential failure-finding tasks, such 

inspections, may also be appropriate.

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3. CMRs are designed to verify that a certain failure has or has not occurred, and do not provide any preventative maintenanc

the failure clock to zero” for latent failures by verifying that the item has not failed, or caused repair if it has failed. Because t

failure is a key element in the calculations used in a safety analysis performed to show compliance with Title 14 CFR § 25.time will have a significant effect on the resultant overall failure probability of the system. The CMR task interval should be 

hours, cycles, or calendar time, as appropriate.

4. The type certification process assumes that the airplane will be maintained in a condition of airworthiness with respect to its 

condition. The process described in AC 25-19 is not intended to establish normal maintenance tasks that should be define

Analysis process. Neither is this process intended to establish CMRs for the purpose of providing supplemental margins of late in the type design approval process.

5. CMRs should not be confused with required structural inspection programs and are to be developed and administered sepa

inspection programs.

CMR TYPESCMR tasks are divided into two categories: One Star CMRs (*) and Two Star CMRs (**). They are defined as follows:

1. One Star CMRs (*) - The tasks and intervals specified are mandatory and cannot be changed, escalated, or deleted withou

FAA Oversight Office.

2. Two Star CMRs (**) - Task intervals may be adjusted in accordance with each operator’s approved escalation program or a

program in a like manner for any MRB Report task, but may not be deleted without prior FAA Oversight Office approval.

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ESCALATION OF TWO STAR CMRs (**)All Two Star CMRs (**) can be managed and controlled the same as any MRB Report task; however, they can not be deleted f

without prior FAA Oversight Office approval. For operators with approved escalation practices or an approved reliability progra

analytical techniques are used to make adjustments to an operator’s maintenance program. It has been demonstrated that the maintenance program does not give rise to undue escalations; consequently, the escalation of Two Star CMR (**) intervals withmaintenance program will be properly managed by the operator subject to local regulatory authority approval.

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EXCEPTIONAL SHORT-TERM EXTENSIONSSince CMR intervals are based on statistical averages and reliability rates, an exceptional short-term extension of 10% for each document may be made, except as noted in Item 1, without jeopardizing safety. The local regulatory authority or a Principle Maconcur with any exceptional short-term extensions before they take place using procedures established with the local regulatormanuals. The “exceptional short-term extension” process is applicable to CMR intervals. It should not be confused with the opescalation” program for normal maintenance tasks described in the operators’ manuals and in the Flight Standards Handbook 8

The FAA Oversight Office has accepted that these exceptional short-term extensions may be granted without consultation with 1. The term “exceptional short-term extension” is defined as an increase in a CMR interval that may be needed to cover an un

situation. All CMRs listed in this section have been approved with an exceptional short-term extension of 10%, except as n• CMR 25-CMR-01, which has been approved for a short-term extension, is restricted to a maximum of 90 days.

2. Repeated use of extensions, either on the same airplane or on similar airplanes in an operator’s fleet, should not be used a

management practices. Exceptional short-term extensions must not be used for fleet CMR extensions.

3. After a CMR has experienced an exceptional short-term extension, the CMR interval will revert back to its interval listed in t

FAA Oversight Office must approve, prior to its use, any desired extension not explicitly listed above.

NOTE: This exceptional short-term extension listed above applies to airlines that fall under the United States FAA jurisdiction 

under the U.S. FAA jurisdiction should obtain interval extension approvals from their local regulatory agency.

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POST-CERTIFICATION CHANGES TO CMRsAny post certification changes to CMRs should be reviewed by the 747 Certification Maintenance Coordination Committee (CM

FAA Oversight Office:1. Since the purpose of a CMR is to limit the exposure time to a given significant latent failure as part of an engineering analysis 

instances of a CMR task repeatedly finding that no failure has occurred may not be sufficient justification for deleting the tabetween repetitive performances of the CMR task. In general, * CMRs are not good candidates for escalation under an ope

* CMR task change or interval escalation can only be made if world fleet service experience indicates that certain assumpti

failure rates made early during the engineering analysis were overly conservative, and a re-calculation of system reliability certain components reveals that the * CMR task or interval may be changed.

2. The introduction of a new CMR or any change to an existing CMR should be reviewed by the same process used during in

important that operators be afforded the same opportunity to participate that they received during the original certification o

allow the operators to manage their own maintenance programs.

3. In the event that later data provide sufficient basis for relaxation of a CMR (less restrictive actions to be performed), the cha

an FAA Oversight Office approved change to this CMR document.

4. If the requirements of an existing CMR must be increased (more restrictive actions to be performed), it will be implemented 

document and enforced by an FAA Airworthiness Directive (AD).

5. After initial aircraft certification, the only basis for adding a new CMR is in association with the certification of design change

6. A new CMR created as part of a design change should be part of the approved data for that change and added to this CMR In the event that a CMR is revised, Boeing will document it by preparing a revision to this document that will be approved by the 

This revision will then be forwarded to all 747-100/200/300/SP operators and the FAA Oversight Office.

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PAGE FORMAT: CMRs

COLUMN EXPLANATIONCMR ITEM NUMBER

Each task is given a unique CMR Item Number. The first and second digits are the ATA Chapter Number.

TYPE CMR TYPE:

CMRs are categorized into one or two star CMRs based on whether or not they can be escalated by the operator FAA Oversight Office approval.* Cannot be escalated or deleted without prior FAA Oversight Office approval.** Can be escalated based on the operator’s approved program for continued airworthiness based on continuous 

surveillance; however, these tasks cannot be deleted without prior FAA Oversight Office approval.

RELATED MRBR ITEM NUMBER

This column is for the related MRB Report (MRBR) Item Number, if there is an applicable MRBR Item Number. Noa one-to-one relationship to an MRBR Item Number.

TASK TASK TYPES/CATEGORIES

LUB = LubricationSVC = ServicingOPC = Operational CheckVCK = Visual CheckGVI = General Visual Inspection

DET = Detailed InspectionSDI = Special Detailed InspectionFNC = Functional CheckRST = RestorationDIS = Discard

CMR INTERVAL Task frequencies are specified in terms of a usage parameter such as flight hours, cycles or calendar time.APPLICABILITYAPL ENG

Applicable Airplane Model and Engine.

TASK DESCRIPTION

Description of the task to be performed.

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CMR TASKS

CMR ITEM 

NUMBER TYPE

RELATED 

MRBR ITEM 

NUMBER TASK

CMR 

INTERVAL

APPLICABILITY

APL ENG TASK DESCR

25-CMR-01 * DIS 9 YRS NOTE ALL Discard the Flight Deck Security Adams 

Applicability Note: Airplanes with any of accomplished: 747-25-3314, 747-25-332

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C. AIRWORTHINESS LIMITATIONS – SYSTEMS

INTRODUCTIONThe airplane systems maintenance requirements described in this AWL document result from various 747-100/200/300/SP airp

with the FAA. This Airworthiness Limitations section is FAA-approved and specifies maintenance required under Title 14 CFR § 

Federal Aviation Regulations, unless an alternative program has been FAA Oversight Office approved. The AWLs may only be the FAA Oversight Office. If the maintenance requirements cannot be accomplished due to repairs and/or modifications, an alteacceptable to the FAA Oversight Office, must be used.An AWL may be an Airworthiness Limitation Instruction (ALI) or a Critical Design Configuration Control Limitation (CDCCL).CDCCLs are a means of identifying certain design configuration features intended to preclude a fuel tank ignition source for the 

airplane as required under Special Federal Aviation Regulation No. 88 (SFAR 88) – Fuel Tank System Fault Tolerance EvaluatTitle 14 CFR § 25.981 – Fuel Tank Ignition Prevention. CDCCLs are mandatory and cannot be changed or deleted without the 

FAA Oversight Office. A critical fuel tank ignition source prevention feature may exist in the fuel system and its related installatfailure condition were to develop, could interact with the fuel system in such a way that an unsafe condition would develop with

adherence to configuration, methods, techniques, and practices as prescribed is required to ensure compliance with the CDCCmethods, techniques or practices not contained in the applicable CDCCL must be approved by the FAA Oversight Office. For e"maintenance" includes maintaining any installation during alterations; therefore, adherence to the CDCCL is required during m

ALIs identify inspection tasks that must be done to maintain the design level of safety for the operational life of the airplane to pALIs are mandatory and cannot be changed or deleted without the approval of the FAA Oversight Office. Strict adherence to m

practices as prescribed is required to ensure the ALI is complied with. Any use of methods, techniques or practices not containapproved by the FAA Oversight Office.

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REGULATORY AGENCY APPROVALAny deviations from the published AWL instructions included in this document require approval from the FAA Oversight Office. 

under the U.S. FAA jurisdiction only and to airplanes registered in the U.S. Operators who are not under the U.S. FAA jurisdictifrom their own local regulatory agency for any deviations from the listed AWL instructions.AWL REVISION PROCESSIn the event that an AWL is revised, Boeing will prepare a revision to this document that will be approved by the FAA Oversight 

then be forwarded to all 747-100/200/300/SP operators and the FAA Oversight Office.ACCOMPLISHMENT INSTRUCTIONS – GENERAL INFORMATIONThe listed AWLs may make reference to Instructions for Continued Airworthiness which are included in other Boeing document• When a document is cited using the words "in accordance with" in an airworthiness limitation, the cited document (or docum

followed to ensure that the critical design feature is maintained. Any deviation from the cited document requires FAA Overs

• When a document is cited using the words "refer to" in an airworthiness limitation, the cited document (or document section

complying with the airworthiness limitation. An alternative procedure may be developed by an operator in accordance with 

maintenance program/manual.

For electrical bonding and grounding requirements, refer to the Boeing Standard Wiring Practices Manual (SWPM) 20-20.

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USE OF ALTERNATE OR EQUIVALENT TOOLS, TEST EQUIPMENT OR MATERIALSFor AWLs which require the use of certain tools, test equipment or materials, use of alternate or equivalent tools, test equipmen

approval from the FAA Oversight Office.The Component Maintenance Manuals (CMMs) listed in the AWLs as “in accordance with” and not “refer to” are currently FAA If the CMM allows the use of alternate or equivalent tools, test equipment or materials, use of an alternate or equivalent tool, tedoes not require further approval by the FAA Oversight Office.EXCEPTIONAL SHORT-TERM EXTENSIONSSince AWL intervals are based on estimations of the probability of an event, an exceptional short-term extension for each syste

document may be made without jeopardizing safety. The local regulatory authority or a Principal Maintenance Inspector must c

short-term extensions before they take place using procedures established with the local regulatory authority in the operators' m

short-term extension" process is applicable to AWL intervals. It should not be confused with the operator's "short-term escalatimaintenance tasks described in the operators' manuals and in the Flight Standards Handbook 8900.1 FSIMS.The FAA Oversight Office has accepted that these exceptional short-term extensions may be granted without consultation with 1. The term “exceptional short-term extension” is defined as an increase in a system AWL interval that may be needed to cove

pected situation. All AWLs listed in this section have been approved with an exceptional short-term extension of 30 days.

2. Repeated use of extensions, either on the same airplane or on similar airplanes in an operator's fleet, should not be used a

management practices. Exceptional short-term extensions must not be used for fleet AWL extensions.

3. After a system AWL has experienced an exceptional short-term extension, the AWL interval will revert back to its interval lis

FAA Oversight Office must approve, prior to its use, any desired extension not explicitly listed above.

NOTE: This exceptional short-term extension listed above applies to airlines that fall under the U.S. FAA jurisdiction only. Op

U.S. FAA jurisdiction should obtain interval extension approvals from their local regulatory agency.

JUN 2014
747-100/200/300/SP AIRWORTHINESS LIMITATIONS AND CERTIFICATION MAINTE

D6-13747-CMR

BOEING PROPRIETARY - Copyright (c) - Unpublished Work - See title page for details 

DEFINITIONSRemoved or Replaced: Defined as removal or replacement of a component, as well as partial removals.Disturbed: Defined as interference, movement or change to the arrangement or order of the referenced component.New wiring: Defined as any alteration that installs wiring that is added to the airplane after initial Airplane Airworthiness Certificdate that the Airworthiness Limitations and Certification Maintenance Requirements document, D6-13747-CMR, was first incormaintenance program, whichever is later.Sealant: Defined as sealant type BMS 5-45 or equivalent in accordance with SRM 51-10-06 for inside of fuel tank and sealant 

equivalent in accordance with SRM 51-10-06 for outside of the fuel tank.FAA Oversight Office: Defined as the FAA office that currently has oversight responsibility for the type certificate of the Boeing aircraft. At the time of publication, the FAA Oversight Office is the FAA BASOO.SUPPORTING DOCUMENTATIONStrict adherence to methods, techniques and practices as prescribed is required to ensure the ALI or CDCCL is complied with. manufacturer's maintenance procedures when performing maintenance that has an effect on an ALI or CDCCL. If operators do can increase the risk of an unsafe condition. Any use of methods, techniques or practices not contained in these ALIs or CDCC

the FAA Oversight Office.

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PAGE FORMAT: SYSTEMS AIRWORTHINESS LIMITATIONS

COLUMN EXPLANATIONAWL NUMBER Each task is given a unique AWL Item Number. The first and second digits are the ATA Chapter Number.TASK ALI = Airworthiness Limitation Instruction. These tasks are inspections that should be performed at the listed int

CDCCL = Critical Design Configuration Control Limitations.

INTERVAL Task frequencies are specified in terms of a usage parameter such as flight hours, cycles or calendar time.

APPLICABILITY Airplane model applicability.DESCRIPTION Description of the task to be performed or critical design configurations aspects that cannot be changed without v

of the design.

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D6-13747-CMR

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C.1 FUEL TANK IGNITION PREVENTION

This section contains an FAA approved program of scheduled inspections and design limitations for operators to incorporate in

program for this type design to meet the new standards and assumptions introduced by Title 14 CFR § 25.981 and SFAR 88. SSystem Fault Tolerance Evaluation Requirements and Title 14 CFR § 25.981 – Fuel Tank Ignition Prevention require maintenalimitations for certain fuel tank critical design configurations.Paragraph 2(a) of SFAR 88 and Paragraph (b) of the new standard introduced by Title 14 CFR § 25.981 (Amendment 25-102) approval holders of Type Certificates (TCs) and Supplemental Type Certificates (STCs) of large transport airplanes to conduct tank systems. The purpose of the safety review is to identify design features that may result in development of ignition sources 

System AWLs are mandatory maintenance actions required to ensure that unsafe conditions identified by the SFAR 88 safety rnot introduced into the fuel tank system as a result of configuration changes, repairs, alterations, or deficiencies in the maintenathe operational life of the airplane.

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747-100/200/300/SP AIRWORTHINESS LIMITATIONS AND CERTIFICATION MAINTE

AWLs – FUEL TANK IGNITION PREVENTION

AWL Number Task Interval Applicability Description

28-AWL-01 ALI 12 YR ALL External Wires Over Center Fuel Tank

Concern: Potential for chafing and arcing to Center Fuel Tank UpPerform a detailed inspection of the wire bundles routed over the main deck floor boards in accordance with Boeing AMM 28-11-00 chafing, and to verify that the wire bundle is not in contact with sudiscrepancies are found, repair in accordance with the Boeing StaD6-54446.

28-AWL-02 CDCCL N/A ALL External Wires Over Center Fuel Tank 

Concern: Potential for wire chafing and arcing to Center Fuel TanIf any maintenance is performed in the area under the main deck ffuel tank, verify the following:1. Maintain the existing wire bundle routing and clamping.2. Installation of any new wire bundles must be in accordance wi

Practices Manual D6-54446.

3. All wire bundles over the center fuel tank are inspected in acco

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28-AWL-03 ALI 12 YR ALL Fuel Quantity Indicating System (FQIS) – Out of Tank Wiring Ligh

Ground TerminationConcern: Potential for Lightning induced voltages on the FQIS wiPerform the following check to ensure the functional integrity of thtermination in accordance with Boeing AMM 20-55-54:1. Visually inspect all connectors at the location being tested to e

includes connector plugs and backshells.

2. Use a Loop Resistance Tester P/N 906-10246-2 or 906-10246

resistance of the shield to ground termination for the following Loop resistance for Overbraid connector bundles:The loop resistance shall not exceed 40 milliohms for connectowire bundle number BAC3106-12 (Main Tank 3).The loop resistance shall not exceed 40 milliohms for connectoverbraid wire bundle number BAC3106-7 (Center Tank).The loop resistance shall not exceed 40 milliohms for connectowire bundle number BAC3106-12 (Main Tank 2).Loop resistance for IFQTs connector bundles:The loop resistance shall not exceed 78 milliohms for connect

bundle number W3119 (Right Reserve #3/ Aux #4 Outboard WThe loop resistance shall not exceed 78 milliohms for connectbundle number W3119 (Right Reserve #4 Inboard Wing Tank)The loop resistance shall not exceed 90 milliohms for connectbundle number W3119 (Right Main #4 Outboard Wing Tank).The loop resistance shall not exceed 90 milliohms for connectbundle number W3119 (Right Main # 3 Inboard Wing Tank).The loop resistance shall not exceed 119 milliohms for connec

bundle number Vendor X121(Center Tank).

(continued on next page)

AWL Number Task Interval Applicability Description

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28-AWL-03 ALI 12 YR ALL Fuel Quantity Indicating System (FQIS) – Out of Tank Wiring Ligh

Ground Termination (Continued)

Loop resistance for IFQTs connector bundles, continued:The loop resistance shall not exceed 90 milliohms for connect

bundle number W3115 (Left Main #2 Inboard Wing Tank). The loop resistance shall not exceed 90 milliohms for connectbundle number W3115 (Left Main #1 Outboard Wing Tank).The loop resistance shall not exceed 78 milliohms for connectbundle number W3115 (Left Reserve #1 Inboard Wing Tank).The loop resistance shall not exceed 78 milliohms for connectbundle number W3115 (Left Reserve #2/ Aux #1 Outboard Wi

28-AWL-04 CDCCL N/A ALL FQIS – Out of Tank Wiring Lightning Shield to Ground Terminatio

Concern: Potential for Lightning induced voltages on the FQIS wiIf any maintenance is performed on the FQIS wire bundle in the ufuselage), verify the following:1. Presence of shielded wiring.2. The shield ground is terminated in accordance with Boeing SW3. The installation is checked in accordance with 28-AWL-03.

AWL Number Task Interval Applicability Description

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28-AWL-05 CDCCL N/A All airplanes 

that have 

incorporated 

Service Bulletin 

747-28A2239.

Lightning Protection – Engine Fuel Feed Line Fuel Tank PenetratConcern: Potential for arcing, sparking or filament heating inside tthe bulkhead fitting and the spar during a lightning strike event.The following must be maintained in accordance with Boeing AMM or attached tubing are removed and replaced:1. Verify electrical fay surface bond from bulkhead fitting to struct

(0.5 milliohms) or less.

2. Install full-bodied fillet seal encapsulating the bulkhead fitting t

inside the tank.

3. Install full bodied fillet seal encapsulating the first coupling inte4. Verify an electrostatic bonding jumper presence between the s

mating with the bulkhead fitting inside the tank.NOTE: Step 2 is not applicable to airplanes with Rolls Royce 

28-AWL-06 CDCCL N/A All airplanes 

that have 

incorporated 

Service Bulletin 

747-29A2104.

Lightning Protection – Hydraulic Line Fuel Tank Penetration Concern: Potential for arcing or sparking inside the tank at the in

fitting and the spar during a lightning strike event.The following design features must be maintained in accordance the bulkhead fitting is removed and replaced:1. Verify electrical fay surface bond from bulkhead fitting to struct

0.001 ohm (1 milliohm) or less.

2. Install fillet seal on the fitting to the tank wall interface outside 3. Install full bodied fillet seal encapsulating the fitting to the tank 

the tank.

4. Verify an electrostatic bonding jumper exists between the struc

Exchanger inside the tank.

5. Verify electrical bond from structure to the Hydraulic Heat Exc

0.005 ohms (5 milliohms) or less.

AWL Number Task Interval Applicability Description

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747-100/200/300/SP AIRWORTHINESS LIMITATIONS AND CERTIFICATION MAINTE

28-AWL-07 CDCCL N/A ALL AC Pump and DC Pump Maintenance

Concern: Potential for maintenance error during pump overhaul. 

ignition source prevention means (i.e., flame arrestor, thermal fusemeans, etc.) that must be maintained if pump is overhauled.Repair and overhaul of Fuel Pumps must be in accordance with m

Maintenance Manual (CMM) Numbers 28-22-07 Revision Numbe3, 28-22-06 Revision Number 6, 28-31-05 Revision Number 1, 28or later revisions of these CMMs that have been approved by the 

28-AWL-08 CDCCL N/A ALL AC Fuel Pump Fault Current Bonding Path

Concern: Potential for fault current path through the pump housin

Electrical faults internal to the fuel pump motor impeller are by deimpeller assembly to the bonding straps on the front face of the mstructure outside the tank. The bonding straps ensure that fault custructure outside the tank until the circuit breaker and/or GFI has the pump.The following features must be maintained during pump replacemFor Hydro-Aire pumps:1. The presence of two bonding straps.2. The motor impeller bonding resistance across the jumpers to s

not more than 0.0002 ohms (0.2 milliohms).NOTE: Service Bulletin 747-28A2033 adds a bonding jumper a(0.2 milliohms) requirement for airplanes LN 1-167).

AWL Number Task Interval Applicability Description

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D6-13747-CMR

BOEING PROPRIETARY - Copyright (c) - Unpublished Work - See title page for details 

28-AWL-09 ALI 18 MTH All airplanes 

Line Number 

258 and on that 

have 

incorporated 

Service Bulletin 

747-28-2053.

Fuel Override Jettison Pump Ground Fault Interrupter (GFI)Concern: Potential for pump housing burn-through, either internal result of major arcing due to electrical failure (i.e., damaged elector lead wire to housing/end cap shorting).The GFI is designed to detect electrical faults and open the circuithrough. The following maintenance check is required in order to ethe GFI circuit:1. Operationally check the GFI of all Override/Jettison pumps, in a

28-31-00. 

2. Operationally check the GFI of all Fuel Boost Pumps, and A/C 

accordance with Boeing AMM 28-22-00. For airplanes that inc747-28-A2053 for Override/Jettison pumps and Service Bulletin Boost Pumps and A/C Scavenge pump.

AWL Number Task Interval Applicability Description

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747-100/200/300/SP AIRWORTHINESS LIMITATIONS AND CERTIFICATION MAINTE

28-AWL-10 CDCCL N/A ALL Lightning, Fault Current or Hot Short Protection – Fuel Tank Pene

Concern: Potential for arcing or sparking inside the tank at a condinterface as a result of electrical fault currents or lightning strike evwithin the ground electrical path.Any repair or alteration involving new or altered penetrations to thwith fasteners, adding a bracket, bulkhead fitting or equipment, etfeatures of the existing equipment penetrations (such as fuel measfueling manifold, fuel temperature sensor, and motor operated fuerequires approval from the FAA Oversight Office.However, no additional FAA Oversight Office approval is required accomplished in accordance with:1. Boeing Structural Repair Manual procedures, and/or2. Boeing Service Bulletins, and/or3. Boeing ODA approved repair/alteration instructions;where all the required procedures that relate to the new or altered 

the statement, "These data have been reviewed by the Boeing ODprevention requirements, and no further approval from the FAA Osatisfy the requirements of CDCCL 28-AWL-10 provided the repai

accordance with these instructions."Note: Electrical bonding of fittings and brackets and/or cap sealin

sealing of component interface to structure inside and/or outside t

AWL Number Task Interval Applicability Description

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747-100/200/300/SP AIRWORTHINESS LIMITATIONS AND CERTIFICATION MAINTE

D6-13747-CMR

BOEING PROPRIETARY - Copyright (c) - Unpublished Work - See title page for details 

28-AWL-11 CDCCL N/A ALL Fuel Quantity Indicating System (FQIS) – Out of Tank Wiring Insta

Concern: Potential for hot shorts and EMI induced voltages on the to enter the fuel tank.For airplanes incorporating Isolated Fuel Quantity Transmitter (IF

747-28-2234, the FQIS wiring is defined as the wiring between thFor airplanes not incorporating IFQT, the FQIS wiring is defined aindicators and the fuel tank.Routing and installation of any new wiring must use wire types BM

BMS 13-58, and not be within a 2-inch radius of the FQIS wiring. separation greater than 1⁄2 inch must be maintained from FQIS wir

28-AWL-12 CDCCL N/A ALL Center Wing Tank Fueling Valve – Fault Current Bond

Concern: Potential for arcing or filament heating inside the center 

The following design features must be maintained in accordance 28-21-13 when the center wing tank fueling valve is removed and 1. Bond resistance measurement from the valve body to the rear 

(10 milliohms).

This installation is checked as specified in 28-AWL-13.

28-AWL-13 ALI 12 YR ALL Center Wing Tank Fueling Valve – Fault Current Bond 

Concern: Potential for arcing or filament heating inside the center 

Perform a bonding check procedure in accordance with Boeing A1. Verify the bond from the exposed threads on the valve mounti

control unit is 0.005 ohms (5 milliohms).

2. Verify the bond from the exposed threads on the valve mountin

is 0.010 ohms (10 milliohms). If the resistance is higher than tthe bonds in accordance with Boeing SWPM 20-20-00.

AWL Number Task Interval Applicability Description

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747-100/200/300/SP AIRWORTHINESS LIMITATIONS AND CERTIFICATION MAINTE

28-AWL-14 CDCCL N/A ALL Fuel Tank Access Doors Configuration

Concern: Potential for arcing or sparking inside the tank at the intetank structure as a result of a direct strike or conducting currents tThe following must be maintained during fuel tank access door inBoeing AMMs 28-11-01, 28-11-02, or 28-11-03: 1. Verify presence of a molded rubber seal positioned around the 

door that mates with the wing skin inside the tank.

2. Apply grease to both sides of the knitted aluminum mesh gask3. Install the greased knitted aluminum mesh gasket between the 

and the wing skin to establish the electrical conductivity betwewing skin.

28-AWL-15 CDCCL N/A ALL Fuel Quantity Indicating System (FQIS) – Repair of In-Tank Hardw

and Compensators) Concern: Potential for maintenance error during repair of in-tank hcompensators and densitometers). Arc gaps may develop that coinside the fuel tank.Repair and overhaul of FQIS tank units, compensators, and densitwith manufacturer Component Maintenance Manual (CMM) Num

Number 13, 28-40-12 Revision Number 9, 28-40-16 Revision NumNumber 8, 28-40-15 Revision Number 0 or later revisions of these approved by the FAA Oversight Office.

AWL Number Task Interval Applicability Description

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D6-13747-CMR

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28-AWL-16 CDCCL N/A ALL Fuel Quantity Indicating System (FQIS) – Repair of In-Tank Wire 

Concern: Potential for error during repair or replacement of in-tandevelop that could result in an ignition source inside the fuel tank.Repair and overhaul of FQIS in-tank wire harness must be in acco20-14-12.Installation of FQIS in-tank wire harness must be in accordance wInstallation of FQIS spar penetration must be in accordance with Bthe following when installing the spar FQIS penetrations:

1. New O-rings are installed.2. A fillet seal is applied between the perimeter of the bulkhead r

surface in the tank around the connector inside and outside th

3. The bulkhead receptacle screws are tightened to the torque va

AMM Task 28-41-09.

28-AWL-17 CDCCL N/A ALL Fault Current Detectors Repair 

Concern: Potential for maintenance error during Fault Current Debe introduced to pumps creating an ignition source.Repair and overhaul of Fault Current Detectors must be in accordComponent Maintenance Manual (CMM) Number 28-31-22 RevisCMM that has been approved by the FAA Oversight Office.

28-AWL-18 CDCCL N/A ALL Resetting Tripped Fuel Pump Circuit Breakers or Ground Fault In

Concern: Potential for arcing or sparking inside the tank between housings and outside the tank between pump wiring and structure Verify it is safe to reset the circuit breaker(s) or GFI(s) by following troubleshooting procedures. Fault(s) that resulted in circuit breakisolated and corrected prior to reset.

AWL Number Task Interval Applicability Description

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747-100/200/300/SP AIRWORTHINESS LIMITATIONS AND CERTIFICATION MAINTE

28-AWL-19 CDCCL N/A All airplanes 

that have 

incorporated 

Service Bulletin 

747-28-2234.

Isolated Fuel Quantity Transmitter (IFQT)Concern: Potential for maintenance error during IFQT repair.Due to intrinsic safety requirements that the IFQTs must adhere torepairable by operators or third party mod shops. Transmitters mmanufacturer for repair and overhaul.

28-AWL-20 CDCCL N/A All airplanes 

that have 

incorporated 

Service Bulletin 

747-28A2291

Reserve Tank Fueling Valve-Induced Lightning Protection BondConcern: Potential for arcing or filament heating inside the center 

fuel tank.The following design features must be maintained in accordance when the reserve tank fueling valve controller is removed and rep1. Two bonding jumpers between the valve controller and structu2. The bonding resistance from the mounting bolt to structure (sp

0.0015 ohms (1.5 milliohms).

AWL Number Task Interval Applicability Description

JUN 2014
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D6-13747-CMR

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28-AWL-21 CDCCL N/A All airplanes 

that have 

incorporated 

Service Bulletin 

747-28A2292

Fault Current Protection – Motor Operated Valve (MOV) ActuatorConcern: Potential for arcing or sparking inside the fuel tank at a 

structure interface as a result of electrical fault current event.The following design features must be maintained in accordance 28-16-01, 28-16-04, 28-22-01, 28-22-02, 28-25-02, 28-31-04, and I. If the MOV actuator is mounted to the spar with an adapter plat

1. Maintain the following if the adapter plate is removed and 

a. Verify electrical fay surface bond resistance between the ada

0.0005 ohms (0.5 milliohms) or less.

b. Install fay surface seal between the adapter plate and the spa

c. Cap seal the four bolts that attach the adapter plate to the spa

around the edge of the hole and on the stationary part of the 

d. Install sealed electrical fay surface bond and fay surface sea

surfaces of the index plate and the adapter plate.

e. Install sealed electrical fay surface bond and fay surface sea

of the actuator and the index plate. 

f. With the bonding jumper not installed, verify electrical bondin

actuator mounting feet and the spar is 0.0025 ohms (2.5 milli

g. Prior to attachment of the bonding jumper to the actuator, veri

between the loose end of the bonding jumper and the spar is less.

h. Attach the bonding jumper to the actuator bonding tab using 

bond. 

2. Maintain the following if the index plate is removed and re

a. Install sealed electrical fay surface bond and fay surface sea

mating surfaces of the index plate and the adapter plate. 

b. Install sealed electrical fay surface bond and fay surface sea

of the actuator and the index plate.

c. With the bonding jumper not installed, verify electrical bondin

actuator mounting feet and the spar is 0.0025 ohms (2.5 milli

 (Continued on next page)

AWL Number Task Interval Applicability Description

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747-100/200/300/SP AIRWORTHINESS LIMITATIONS AND CERTIFICATION MAINTE

28-AWL-21,

Continued

CDCCL N/A All airplanes 

that have 

incorporated 

Service Bulletin 

747-28A2292

Fault Current Protection – Motor Operated Valve (MOV) Actuator 

d. Prior to attachment of the bonding jumper to the actuator, veri

between the loose end of the bonding jumper and the spar is less.

e. Attach the bonding jumper to the actuator bonding tab using 

bond.

3. Maintain the following If the MOV actuator is removed and 

a. Install sealed electrical fay surface bond and fay surface sea

surfaces of the actuator and the index plate.

b. With the bonding jumper not installed, verify electrical bondin

actuator mounting feet and the spar is 0.0025 ohms (2.5 milli

c. Prior to attachment of the bonding jumper to the actuator, veri

between the loose end of the bonding jumper and the spar is less,

d. Attach the bonding jumper to the actuator bonding tab using 

bond.

II. If the MOV actuator is mounted without an adapter plate. 

4. Maintain the following If the MOV actuator is removed and 

a. Install sealed electrical fay surface bond between the mating 

and 

b. With the bonding jumper not installed, verify electrical bondin

actuator mounting feet and the spar is 0.005 ohms (5 milliohm

c. Prior to attachment of the bonding jumper to the actuator, veri

between the loose end of the bonding jumper and the spar is less,

d. Attach the bonding jumper to the actuator bonding tab using 

bond.

AWL Number Task Interval Applicability Description

JUN 2014
747-100/200/300/SP AIRWORTHINESS LIMITATIONS AND CERTIFICATION MAINTE

D6-13747-CMR

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28-AWL-22 ALI 1 YR All airplanes 

that have 

incorporated 

Service Bulletin 

747-28A2288

Center Tank Override Fuel Pump Inlet Protection and Power FailConcern: Dry running the center tank fuel pumps has the potentiasources developing at the pump inlet due to either frictional heatincontacting the pump rotating elements, rotating elements contactijournal bearings due to bearing contamination or failure.The center tank override fuel pump inlet protection and power faile

on flight engineer procedures. However, an additional center tank 

has been added to the P10 automatic flight control panel. The folloprotect against latent faults of this additional center tank fuel pumVerify continued functionality of the P10 panel center tank fuel ove

accordance with Boeing AMM 28-31-00.

28-AWL-23 ALI 1 YR 747 Classic 

airplanes

that have 

incorporated 

Service Bulletin 

747-28A2261

Main Fuel Tank Boost Fuel Pump Ground Fault Interruption (GFI) CWT Electrical Scavenge Pump Ground Fault Interruption (GFI) CInboard Main Tank Jettison Pump Ground Fault Interruption (GFI) 

Concern: GFI is installed to protect against burn-through of the pagainst overheating of the pump cavity and/or auto ignition tempethe housing, due to electrical arcing.Perform an Operational Test of all Main Fuel Tank Boost Pump, einboard main tank jettison pump GFI Control relays in accordance 

AWL Number Task Interval Applicability Description

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BOEING PROPRIETARY - Copyright (c) - Unpublished Work - See title page for details 

747-100/200/300/SP AIRWORTHINESS LIMITATIONS AND CERTIFICATION MAINTE

28-AWL-24 CDCCL N/A ALL airplanes 

that have 

incorporated 

Service Bulletin 

747-28A2306

Fuel Boost Pump Wires In Conduit Installation - In Fuel TankConcern: Potential for the boost pump wiring to chafe and arc to thsource in the fuel tank. The boost pump wires that are in the condincorporated a conduit liner and a Teflon Sleeve to protect from wi

shield (grounded at both ends) that is monitored by the GFI for an 

a pump power wire short within the conduit.The following design features must be verified when the pump wirremoved or replaced (refer to Boeing AMM 28-22-03):1. Jacketed and shielded (grounded at both ends) wiring is instal2. A Teflon sleeve is installed.3. A Conduit Liner is installed.NOTE: The above requirement applies to the following Fuel BoosMain Tank No. 1 FWD Fuel Boost PumpMain Tank No. 1 AFT Fuel Boost PumpMain Tank No. 4 FWD Fuel Boost PumpMain Tank No. 4 AFT Fuel Boost Pump.

28-AWL-25 ALI 12 YR ALL airplanes 

that have 

incorporated 

Service Bulletins 

747-57A2327

Teflon Sleeving - Out-of-Tank Wire BundleConcern: Potential for hot short induced voltages on out-of-tank stank due to chafing.Perform a visual (detailed) inspection and verify the following to ebundle Teflon sleeving:1. Teflon sleeving are installed around wire bundle in clamp locat

Bulletin 747-57A2327.

2. Teflon sleeves are not damaged. 3. Clamps are not missing or damaged. 

AWL Number Task Interval Applicability Description

JUN 2014
747-100/200/300/SP AIRWORTHINESS LIMITATIONS AND CERTIFICATION MAINTE

D6-13747-CMR

BOEING PROPRIETARY - Copyright (c) - Unpublished Work - See title page for details 

28-AWL-26 CDCCL N/A ALL airplanes 

that have 

incorporated 

Service Bulletin 

747-28A2204 

but have not 

incorporated 

Service Bulletin 

747-28A2306

Fuel Boost Pump Wires in Conduit Installation - In Fuel TankConcern: Potential for the boost pump wiring to chafe and arc to thsource in the fuel tank.The following design features must be verified when the pump wiremoved or replaced (refer to Boeing AMM 28-22-03):1. A Wiring Jacket and Teflon sleeve, Part Number TFE 2X, are pNOTE: The Teflon sleeve is not repairable. NOTE: The above requirement applies to the following Fuel BoosMain Tank No. 1 FWD Fuel Boost PumpMain Tank No. 1 AFT Fuel Boost PumpMain Tank No. 4 FWD Fuel Boost PumpMain Tank No. 4 AFT Fuel Boost Pump

28-AWL-27 CDCCL N/A ALL airplanes 

that have 

incorporated 

Service Bulletin 

747-57A2327

Teflon Sleeving - Out-of-Tank Wire BundleConcern: Potential for hot short induced voltages on out-of-tank stank due to chafing.The following design features must be verified when out-of-tank sreplaced, in order to ensure the integrity of the wire bundles Teflo1. The Teflon sleeving is installed around the wiring in the clamp l

Bulletin 747-57A2327.

2. Sleeving is not damaged.

AWL Number Task Interval Applicability Description

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747-100/200/300/SP AIRWORTHINESS LIMITATIONS AND CERTIFICATION MAINTE

28-AWL-28 CDCCL N/A ALL Lightning, Fault Current or Hot Short Protection Features - In Tan

Concern: Potential for arcing or sparking inside the tank at a cond

interface as a result of electrical fault currents or lightning strike evwithin the ground electrical path. Sealant damage or lack of propetank ignition prevention features.If any maintenance, preventative maintenance, or alteration is pe

verify the following in the affected areas (including the touchpoints 

tank access point) where work is performed (refer to Boeing AMM 1. Fillet seals around the periphery of the equipment interface wit

not damaged such as peeling off or cracking.

2. Cap seals installed on fasteners and fittings inside the tank are 

peeling off or cracking.

NOTE: Not all fasteners and fittings have cap seals. If fastener or f

will be residual evidence of a previously-installed cap seal areas where installation is required. In addition, all tank strrequire cap seals in accordance with AWL 28-AWL-10.

AWL Number Task Interval Applicability Description

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C.2 IMPACT-RESISTANT FUEL TANK ACCESS DOORS

INTRODUCTIONThe 747 Fuel Tank Access Doors are compliant with FAA Title 14 CFR § 25.963. Specifically, the 747 Impact-Resistant Acces

§ 25.963(e)(1), which requires that all covers located in an area where experience or analysis indicates a strike is likely must be to minimize penetration and deformation by tire fragments, low energy engine debris, or other likely debris. 747-100/200/300 ai

1 - 678, 680 - 684 and 686 - 720 were retrofitted with impact-resistant access doors via Service Bulletin 747-28A2117. Two addretrofitted with impact-resistant doors via Service Bulletin 747-28-2236. These service bulletins also required that the impact-re

“IMPACT-RESISTANT DOOR”. Additionally, the adjacent lower wing surface is stenciled “CAUTION: INSTALL ONLY IMPACT

THIS LOCATION”. All other 747 airplanes were delivered with impact-resistant access doors and stenciling.

Boeing chose to use a CDCCL for the Airworthiness Limitation of the Impact-Resistant Fuel Tank Access Doors. CDCCLs are 

understood by operators to define a design feature that must be maintained throughout the life of the airplane.

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AWLs – IMPACT-RESISTANT FUEL TANK ACCESS DOOR

AWL Number Task Interval Applicability Description

57-AWL-01 CDCCL N/A ALL Impact-Resistant Fuel Tank Access Doors

Concern: A potential exists for non-impact-resistant doors to be installed 

resistant doors. A high energy impact on a non-impact-resistant fuel tank leak, and in the presence of an ignition source, may result in a catastrophImmediately prior to the installation of each of the Fuel Tank Access Doors 545BB, 645BB, 546AB, 646AB, 546BB, 646BB, 552AB, 652AB, 552BB, 6652DB, 552EB, and 652EB, perform the following:

1. Verify that the fuel tank access door is impact-resistant. Impac

smooth inner surface. Doors with visible machined stiffening rnot impact-resistant (refer to Boeing AMM 28-11-02).

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D. LIMIT OF VALIDITY (LOV)

This section provides the Limit of Validity (LOV) in accordance with the requirements of Title 14 CFR § 26.21 (Amendment 26-6

the establishment of an airplane level limit of validity of the engineering data that supports the structural maintenance program period of time, stated as a number of total accumulated flight cycles or flight hours or both, during which it is demonstrated that will not occur in the airplane. The LOVs listed in the following table support operator compliance with Title 14 CFR Sections 121

LIMIT OF VALIDITY FOR THE 747

MODEL FLIGHT CYCLE LOV FLIGHT HOUR LOV

747SR, 747SP, 747-100, 747-100B, 

747-100BSUD, 747-200B, 747-200F, 

747-200C, 747-300

35,000 135,000

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