[Federal Register Volume 87, Number 173 (Thursday, September 8, 2022)]
[Proposed Rules]
[Pages 54919-54922]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 2022-19273]


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DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 39

[Docket No. FAA-2022-1058; Project Identifier AD-2022-00256-T]
RIN 2120-AA64


Airworthiness Directives; The Boeing Company Airplanes

AGENCY: Federal Aviation Administration (FAA), DOT.

ACTION: Notice of proposed rulemaking (NPRM).

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SUMMARY: The FAA proposes to supersede Airworthiness Directive (AD) 
2021-07-09, which applies to all The Boeing Company Model 747-100, 747-
100B, 747-100B SUD, 747-200B, 747-200C, 747-200F, 747-300, 747-400, 
747-400D, 747-400F, 747SR, and 747SP series airplanes. AD 2021-07-09 
requires repetitively inspecting all trim air diffuser ducts or 
sidewall riser duct assemblies (collectively referred to as TADDs) for 
damage, including repetitive structural inspections of the center fuel 
tanks for damage, and applicable on-condition actions. Since the FAA 
issued AD 2021-07-09, the agency has determined that the existing 
requirements do not adequately address the unsafe condition. This 
proposed AD would continue to require repetitive inspections of the 
TADDs for damage with revised compliance times, and repair if 
applicable. This proposed AD would also require repetitive replacement 
of the TADDs and would remove the structural inspections of the center 
fuel tanks. This proposed AD would also prohibit the installation of 
affected parts. The FAA is proposing this AD to address the unsafe 
condition on these products.

DATES: The FAA must receive comments on this proposed AD by October 24, 
2022.

ADDRESSES: You may send comments, using the procedures found in 14 CFR 
11.43 and 11.45, by any of the following methods:
     Federal eRulemaking Portal: Go to regulations.gov. Follow 
the instructions for submitting comments.
     Fax: 202-493-2251.
     Mail: U.S. Department of Transportation, Docket 
Operations, M-30, West Building Ground Floor, Room W12-140, 1200 New 
Jersey Avenue SE, Washington, DC 20590.
     Hand Delivery: Deliver to Mail address above between 9 
a.m. and 5 p.m., Monday through Friday, except Federal holidays.

[[Page 54920]]

    For service information identified in this NPRM, contact Boeing 
Commercial Airplanes, Attention: Contractual & Data Services (C&DS), 
2600 Westminster Blvd., MC 110-SK57, Seal Beach, CA 90740-5600; 
telephone 562-797-1717; internet myboeingfleet.com. You may view this 
service information at the FAA, Airworthiness Products Section, 
Operational Safety Branch, 2200 South 216th St., Des Moines, WA. For 
information on the availability of this material at the FAA, call 206-
231-3195. It is also available at regulations.gov by searching for and 
locating Docket No. FAA-2022-1058.

Examining the AD Docket

    You may examine the AD docket at regulations.gov by searching for 
and locating Docket No. FAA-2022-1058; or in person at Docket 
Operations between 9 a.m. and 5 p.m., Monday through Friday, except 
Federal holidays. The AD docket contains this NPRM, any comments 
received, and other information. The street address for Docket 
Operations is listed above.

FOR FURTHER INFORMATION CONTACT: Nicole S. Tsang, Aerospace Engineer, 
Cabin Safety and Environmental Systems Section, FAA, Seattle ACO 
Branch, 2200 South 216th St., Des Moines, WA 98198; phone and fax: 206-
231-3959; email: [email protected].

SUPPLEMENTARY INFORMATION:

Comments Invited

    The FAA invites you to send any written relevant data, views, or 
arguments about this proposal. Send your comments to an address listed 
under ADDRESSES. Include ``Docket No. FAA-2022-1058; Project Identifier 
AD-2022-00256-T'' at the beginning of your comments. The most helpful 
comments reference a specific portion of the proposal, explain the 
reason for any recommended change, and include supporting data. The FAA 
will consider all comments received by the closing date and may amend 
the proposal because of those comments.
    Except for Confidential Business Information (CBI) as described in 
the following paragraph, and other information as described in 14 CFR 
11.35, the FAA will post all comments received, without change, to 
regulations.gov, including any personal information you provide. The 
agency will also post a report summarizing each substantive verbal 
contact received about this proposed AD.

Confidential Business Information

    CBI is commercial or financial information that is both customarily 
and actually treated as private by its owner. Under the Freedom of 
Information Act (FOIA) (5 U.S.C. 552), CBI is exempt from public 
disclosure. If your comments responsive to this NPRM contain commercial 
or financial information that is customarily treated as private, that 
you actually treat as private, and that is relevant or responsive to 
this NPRM, it is important that you clearly designate the submitted 
comments as CBI. Please mark each page of your submission containing 
CBI as ``PROPIN.'' The FAA will treat such marked submissions as 
confidential under the FOIA, and they will not be placed in the public 
docket of this NPRM. Submissions containing CBI should be sent to 
Nicole S. Tsang, Aerospace Engineer, Cabin Safety and Environmental 
Systems Section, FAA, Seattle ACO Branch, 2200 South 216th St., Des 
Moines, WA 98198; phone and fax: 206-231-3959; email: 
[email protected]. Any commentary that the FAA receives that is 
not specifically designated as CBI will be placed in the public docket 
for this rulemaking.

Background

    The FAA issued AD 2021-07-09, Amendment 39-21486 (86 FR 17899, 
April 7, 2021) (AD 2021-07-09), for all The Boeing Company Model 747-
100, 747-100B, 747-100B SUD, 747-200B, 747-200C, 747-200F, 747-300, 
747-400, 747-400D, 747-400F, 747SR, and 747SP series airplanes. AD 
2021-07-09 was prompted by reports of sealant deteriorating on the 
outside of the center wing fuel tank and analysis showing that sealant 
may deteriorate inside the tank due to excess heat from TADDs. AD 2021-
07-09 was also prompted by reports indicating that the high temperature 
composite material TADD failed. AD 2021-07-09 requires replacing 
original fiberglass fabric material with high temperature composite 
material TADDs, repetitively inspecting the TADDs for damage, and as 
applicable inspecting the center wing fuel tank secondary fuel barrier 
coating and primary sealant for damage, and repairing damage. The 
agency issued AD 2021-07-09 to address potential hot air leakage from 
original fiberglass fabric material or high temperature composite 
material TADD that can cause damage to the center wing fuel tank 
secondary fuel barrier coating and primary sealant, which can cause 
fuel leakage into an ignition zone, possibly resulting in a fire or 
explosion.

Actions Since AD 2021-07-09 Was Issued

    The FAA issued AD 2021-07-09 as an interim action and indicated 
that the FAA might consider additional rulemaking. Since AD 2021-07-09 
was issued, Boeing received further data from operators complying with 
AD 2021-07-09 and continued to investigate the unsafe condition. Based 
on the information Boeing received, the FAA has determined that the 
existing requirements do not adequately address the unsafe condition.

FAA's Determination

    The FAA is issuing this NPRM after determining that the unsafe 
condition described previously is likely to exist or develop on other 
products of the same type design.

Related Service Information Under 1 CFR Part 51

    The FAA reviewed Boeing Alert Requirements Bulletin 747-21A2577 RB, 
Revision 1, dated March 9, 2022. This service information specifies 
procedures for repetitive detailed inspections for damage of TADDs made 
of original fiberglass fabric material and high temperature composite 
material, repetitive replacement of TADDs, and repair of damaged TADDs.
    The FAA also reviewed Boeing Alert Service Bulletin 747-21A2577, 
Revision 1, dated March 9, 2022. This service information specifies, 
among other things, the list of original fiberglass fabric material 
TADD assembly part numbers in Appendix A of Boeing Alert Service 
Bulletin 747-21A2577, Revision 1, dated March 9, 2022, and a list of 
high temperature composite material TADD assembly part numbers in 
Appendix B of Boeing Alert Service Bulletin 747-21A2577, Revision 1, 
dated March 9, 2022. Appendix A and Appendix B of Boeing Alert Service 
Bulletin 747-21A2577, Revision 1, dated March 9, 2022, were not 
included in Boeing Alert Requirements Bulletin 747-21A2577 RB, Revision 
1, dated March 9, 2022. The parts listed in Appendix A are affected 
parts that are prohibited from installation.
    This service information is reasonably available because the 
interested parties have access to it through their normal course of 
business or by the means identified in the ADDRESSES section.

Proposed AD Requirements in This NPRM

    Although this proposed AD does not explicitly restate the 
requirements of AD 2021-07-09, this proposed AD would retain certain 
requirements of AD 2021-07-09. Those requirements are referenced in the 
service information identified previously, except for any differences 
identified as exceptions in the regulatory text of this proposed AD;

[[Page 54921]]

that service information, in turn, is referenced in paragraph (g) of 
this proposed AD. This proposed AD would continue to require repetitive 
inspections of the TADDs for damage (loose connection between a TADD 
and the adjacent duct, delamination, removed surface material, softened 
material, or blackened material on the TADD surface that can be easily 
rubbed off by hand) with revised compliance times, and repair if 
applicable. For certain airplane configurations, the TADDs' repetitive 
inspection intervals were reduced from 3,600 flight hours to 1,200 
flight hours if the number of flight hours since the TADD replacement 
are not known. For airplanes with certain configurations and certain 
conditions, the TADDs' repetitive inspection intervals were increased 
from 1,200 flight hours after replacement to 16,000 flight hours after 
replacement. This proposed AD would also require repetitive replacement 
of the TADDs and would remove the structural inspections of the center 
fuel tanks. In addition, this proposed AD would also prohibit the 
installation of affected parts.
    For information on the procedures and compliance times, see this 
service information at regulations.gov by searching for and locating 
Docket No. FAA-2022-1058.

Costs of Compliance

    The FAA estimates that this AD, if adopted as proposed, would 
affect 104 airplanes of U.S. registry. The FAA estimates the following 
costs to comply with this proposed AD:

                                                 Estimated Costs
----------------------------------------------------------------------------------------------------------------
                                                                                                  Cost on U.S.
            Action                  Labor cost            Parts cost         Cost per  product      operators
----------------------------------------------------------------------------------------------------------------
Retained repetitive             Up to 44 work-     $0......................  Up to $3,740 per   Up to $388,960
 inspections (AD2021-07-09).     hours x $85 per                              inspection cycle.  per inspection
                                 hour = up to                                                    cycle.
                                 $3,740 per
                                 inspection cycle.
Repetitive TADD replacement...  Up to 49 work-     Up to $12,000...........  Up to $16,165 per  Up to $1,681,160
                                 hours x $85 per                              inspection cycle.  per replacement
                                 hour = $4,165                                                   cycle.
                                 per replacement
                                 cycle.
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    The FAA has received no definitive data on which to base the cost 
estimates for the on-condition repairs specified in this proposed AD.
    The FAA has included all known costs in its cost estimate. 
According to the manufacturer, however, some or all of the costs of 
this proposed AD may be covered under warranty, thereby reducing the 
cost impact on affected operators.

Authority for This Rulemaking

    Title 49 of the United States Code specifies the FAA's authority to 
issue rules on aviation safety. Subtitle I, Section 106, describes the 
authority of the FAA Administrator. Subtitle VII, Aviation Programs, 
describes in more detail the scope of the Agency's authority.
    The FAA is issuing this rulemaking under the authority described in 
Subtitle VII, Part A, Subpart III, Section 44701, General requirements. 
Under that section, Congress charges the FAA with promoting safe flight 
of civil aircraft in air commerce by prescribing regulations for 
practices, methods, and procedures the Administrator finds necessary 
for safety in air commerce. This regulation is within the scope of that 
authority because it addresses an unsafe condition that is likely to 
exist or develop on products identified in this rulemaking action.

Regulatory Findings

    The FAA has determined that this proposed AD would not have 
federalism implications under Executive Order 13132. This proposed AD 
would not have a substantial direct effect on the States, on the 
relationship between the national Government and the States, or on the 
distribution of power and responsibilities among the various levels of 
government.
    For the reasons discussed above, I certify that the proposed 
regulation:
    (1) Is not a ``significant regulatory action'' under Executive 
Order 12866,
    (2) Would not affect intrastate aviation in Alaska, and
    (3) Would not have a significant economic impact, positive or 
negative, on a substantial number of small entities under the criteria 
of the Regulatory Flexibility Act.

List of Subjects in 14 CFR Part 39

    Air transportation, Aircraft, Aviation safety, Incorporation by 
reference, Safety.

The Proposed Amendment

    Accordingly, under the authority delegated to me by the 
Administrator, the FAA proposes to amend 14 CFR part 39 as follows:

PART 39--AIRWORTHINESS DIRECTIVES

0
1. The authority citation for part 39 continues to read as follows:

    Authority: 49 U.S.C. 106(g), 40113, 44701.


Sec.  39.13  [Amended]

0
2. The FAA amends Sec.  39.13 by:
0
a. Removing Airworthiness Directive (AD) 2021-07-09, Amendment 39-21486 
(86 FR 17899, April 7, 2021), and
0
b. Adding the following new AD:

The Boeing Company: Docket No. FAA-2022-1058; Project Identifier AD-
2022-00256-T.

(a) Comments Due Date

    The FAA must receive comments on this airworthiness directive 
(AD) action by October 24, 2022.

(b) Affected ADs

    This AD replaces AD 2021-07-09, Amendment 39-21486 (86 FR 17899, 
April 7, 2021) (AD 2021-07-09).

(c) Applicability

    This AD applies to all The Boeing Company Model 747-100, 747-
100B, 747-100B SUD, 747-200B, 747-200C, 747-200F, 747-300, 747-400, 
747-400D, 747-400F, 747SR, and 747SP series airplanes, certificated 
in any category.

(d) Subject

    Air Transport Association (ATA) of America Code 21, Air 
conditioning.

(e) Unsafe Condition

    This AD was prompted by reports of sealant deteriorating on the 
outside of the center wing fuel tank and analysis showing that 
sealant could deteriorate inside the fuel tank due to excess heat 
from trim air diffuser ducts or sidewall riser duct assemblies 
(collectively referred to as TADDs), and by the determination that 
existing requirements do not adequately address the unsafe 
condition. The FAA is issuing this AD to address potential hot air 
leakage from original fiberglass fabric material or high temperature 
composite material TADDs that can cause damage to the center wing 
fuel tank secondary fuel barrier coating and primary sealant, which 
can cause fuel leakage into an ignition zone, possibly resulting in 
a fire or explosion.

[[Page 54922]]

(f) Compliance

    Comply with this AD within the compliance times specified, 
unless already done.

(g) Required Actions

    Except as specified by paragraph (h) of this AD: At the 
applicable times specified in the ``Compliance'' paragraph of Boeing 
Alert Requirements Bulletin 747-21A2577 RB, Revision 1, dated March 
9, 2022, do all applicable actions identified in, and in accordance 
with, the Accomplishment Instructions of Boeing Alert Requirements 
Bulletin 747-21A2577 RB, Revision 1, dated March 9, 2022.
    Note 1 to paragraph (g): Guidance for accomplishing the actions 
required by this AD can be found in Boeing Alert Service Bulletin 
747-21A2577, Revision 1, dated March 9, 2022, which is referred to 
in Boeing Alert Requirements Bulletin 747-21A2577 RB, Revision 1, 
dated March 9, 2022.

(h) Exceptions to Service Information Specifications

    (1) Where the Compliance Time column of the tables in the 
``Compliance'' paragraph of Boeing Alert Requirements Bulletin 747-
21A2577 RB, Revision 1, dated March 9, 2022, uses the phrase ``the 
Revision 1 date of Requirements Bulletin 747-21A2577 RB,'' this AD 
requires using ``the effective date of this AD.''
    (2) Where Boeing Alert Requirements Bulletin 747-21A2577 RB, 
Revision 1, dated March 9, 2022, specifies contacting Boeing for 
repair instructions: This AD requires doing the repair before 
further flight using a method approved in accordance with the 
procedures specified in paragraph (k) of this AD.
    (3) Where Boeing Alert Requirements Bulletin 747-21A2577 RB, 
Revision 1, dated March 9, 2022, refers to ``new high temperature 
composite material TADD,'' for this AD high temperature composite 
material TADD is defined as the list of TADDs, indicated by part 
numbers, in Appendix B of Boeing Alert Service Bulletin 747-21A2577, 
Revision 1, dated March 9, 2022.
    (4) Where Boeing Alert Requirements Bulletin 747-21A2577 RB, 
Revision 1, dated March 9, 2022, refers to ``original fiberglass 
fabric material TADD,'' for this AD, original fiberglass fabric 
material TADD is defined as the list of TADDs, indicated by part 
numbers, in Appendix A of Boeing Alert Service Bulletin 747-21A2577, 
Revision 1, dated March 9, 2022.

(i) Parts Installation Prohibition

    As of the effective date of this AD, no person may install an 
original fiberglass fabric material TADD assembly, having a part 
number listed in Appendix A of Boeing Alert Service Bulletin 747-
21A2577, Revision 1, dated March 9, 2022, on any airplane.

(j) Credit for Previous Actions

    This paragraph provides credit for the actions specified in 
paragraph (g) of this AD, if those actions were performed before the 
effective date of this AD using Boeing Alert Requirements Bulletin 
747-21A2577 RB, dated February 18, 2020, which was incorporated by 
reference in AD 2021-07-09.

(k) Alternative Methods of Compliance (AMOCs)

    (1) The Manager, Seattle ACO Branch, FAA, has the authority to 
approve AMOCs for this AD, if requested using the procedures found 
in 14 CFR 39.19. In accordance with 14 CFR 39.19, send your request 
to your principal inspector or responsible Flight Standards Office, 
as appropriate. If sending information directly to the manager of 
the certification office, send it to the attention of the person 
identified in paragraph (l)(1) of this AD. Information may be 
emailed to: [email protected].
    (2) Before using any approved AMOC, notify your appropriate 
principal inspector, or lacking a principal inspector, the manager 
of the responsible Flight Standards Office.
    (3) An AMOC that provides an acceptable level of safety may be 
used for any repair, modification, or alteration required by this AD 
if it is approved by The Boeing Company Organization Designation 
Authorization (ODA) that has been authorized by the Manager, Seattle 
ACO Branch, FAA, to make those findings. To be approved, the repair 
method, modification deviation, or alteration deviation must meet 
the certification basis of the airplane, and the approval must 
specifically refer to this AD.
    (4) AMOCs approved for AD 2021-07-09 are approved as AMOCs for 
the corresponding provisions of Boeing Alert Requirements Bulletin 
747-21A2577 RB, Revision 1, dated March 9, 2022, that are required 
by paragraph (g) of this AD.

(l) Related Information

    (1) For more information about this AD, contact Nicole S. Tsang, 
Aerospace Engineer, Cabin Safety and Environmental Systems Section, 
FAA, Seattle ACO Branch, 2200 South 216th St., Des Moines, WA 98198; 
phone and fax: 206-231-3959; email: [email protected].
    (2) For service information identified in this AD, contact 
Boeing Commercial Airplanes, Attention: Contractual & Data Services 
(C&DS), 2600 Westminster Blvd., MC 110 SK57, Seal Beach, CA 90740 
5600; telephone 562-797-1717; internet myboeingfleet.com. You may 
view this referenced service information at the FAA, Airworthiness 
Products Section, Operational Safety Branch, 2200 South 216th St., 
Des Moines, WA. For information on the availability of this material 
at the FAA, call 206-231-3195.

    Issued on August 17, 2022.
Christina Underwood,
Acting Director, Compliance & Airworthiness Division, Aircraft 
Certification Service.
[FR Doc. 2022-19273 Filed 9-7-22; 8:45 am]
BILLING CODE 4910-13-P


