[Federal Register Volume 85, Number 184 (Tuesday, September 22, 2020)]
[Proposed Rules]
[Pages 59451-59454]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 2020-20807]


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DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 39

[Docket No. FAA-2020-0848; Product Identifier 2020-NM-088-AD]
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) 
2007-07-03, which applies to certain 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 2007-07-03 
requires repetitive tests to detect hot air leaking from the trim air 
diffuser ducts or sidewall riser duct assemblies (collectively referred 
to as TADDs), related investigative actions, and corrective actions if 
necessary. AD 2007-07-03 also provides an optional terminating action 
for the repetitive tests. Since the FAA issued AD 2007-07-03, operators 
reported high temperature composite material TADDs installed as 
specified in AD 2007-07-03 have also failed. This proposed AD would 
require repetitive inspections of all TADD material for damage and 
applicable on-condition actions. 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 November 6, 
2020.

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 https://www.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.
    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 https://www.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 on the internet at https://www.regulations.gov by searching for and locating Docket No. FAA-2020-
0848.

Examining the AD Docket

    You may examine the AD docket on the internet at https://www.regulations.gov by searching for and locating Docket No. FAA-2020-
0848; 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.

[[Page 59452]]

Comments will be available in the AD docket shortly after receipt.

FOR FURTHER INFORMATION CONTACT: Susan L. Monroe, Aerospace Engineer, 
Cabin Safety and Environmental Systems Section, FAA, Seattle ACO 
Branch, 2200 South 216th St., Des Moines, WA 98198; phone and fax: 206-
231-3570; email: susan.l.monroe@faa.gov.

SUPPLEMENTARY INFORMATION:

Comments Invited

    The FAA invites you to participate in this rulemaking by submitting 
written comments, data, or views. The most helpful comments reference a 
specific portion of the proposal, explain the reason for any 
recommended change, and include supporting data. To ensure the docket 
does not contain duplicate comments, commenters should send only one 
copy of written comments, or if comments are filed electronically, 
commenters should submit only one time.
    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 file in the docket all comments received, as well 
as a report summarizing each substantive public contact with FAA 
personnel concerning this proposed rulemaking. Before acting on this 
proposal, the FAA will consider all comments received on or before the 
closing date for comments. The FAA will consider comments filed after 
the comment period has closed if it is possible to do so without 
incurring expense or delay. The FAA may change this proposal in light 
of the comments received.

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 Susan 
L. Monroe, Aerospace Engineer, Cabin Safety and Environmental Systems 
Section, FAA, Seattle ACO Branch, 2200 South 216th St., Des Moines, WA 
98198; phone and fax: 206-231-3570; email: susan.l.monroe@faa.gov. Any 
commentary that the FAA receives which is not specifically designated 
as CBI will be placed in the public docket for this rulemaking.

Discussion

    The FAA issued AD 2007-07-03, Amendment 39-15003 (72 FR 14395, 
March 28, 2007) (``AD 2007-07-03''), for certain 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 2007-07-03 requires repetitive tests to detect hot air 
leaking from the TADDs, related investigative actions, and corrective 
actions if necessary. AD 2007-07-03 also provides an optional 
terminating action (replacement of the original fiberglass material 
TADDs with high temperature composition material TADDs) for the 
repetitive tests. AD 2007-07-03 resulted from 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 leaking TADDs. The FAA issued AD 2007-07-03 to address leakage of 
fuel or fuel vapors into areas where ignition sources may be present, 
which could result in a fire or explosion.

Actions Since AD 2007-07-03 Was Issued

    Since the FAA issued AD 2007-07-03, operators reported high 
temperature composite material TADDs installed as specified in AD 2007-
07-03 have also failed. Further inspection showed that the high 
temperature composite material TADDs were ruptured, with damaged 
insulation in poor condition. Analysis showed that hot trim air is 
causing material properties degradation of both the original fiberglass 
fabric material and high temperature composite material TADDs, which 
potentially causes hot air leakage from the TADD(s).

Related Service Information Under 1 CFR Part 51

    The FAA reviewed Boeing Alert Requirements Bulletin 747-21A2577 RB, 
dated February 18, 2020. The service information describes procedures 
for repetitive detailed inspections of TADDs made of original 
fiberglass fabric material and high temperature composite material for 
damage and applicable on-condition actions. On-condition actions 
include TADD replacement, detailed inspection of the center wing tank 
secondary fuel barrier and the center wing tank primary sealant for 
damage, a measurement of the electrical conductivity change of the 
upper skin of the center wing tank for indications of damage, other 
replacement as applicable, and repair. 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.

FAA's Determination

    The FAA is proposing this AD because the agency evaluated all the 
relevant information and determined the unsafe condition described 
previously is likely to exist or develop in other products of the same 
type design.

Proposed AD Requirements

    This proposed AD would retain none of the requirements of AD 2007-
07-03. However, the original TADDs specified in AD 2007-07-03, if 
installed, will continue to be inspected per the new proposed 
requirements of this AD. This proposed AD would require accomplishment 
of the actions identified in Boeing Alert Requirements Bulletin 747-
21A2577 RB, dated February 18, 2020, described previously, except for 
any differences identified as exceptions in the regulatory text of this 
proposed AD.
    For information on the procedures and compliance times, see this 
service information at https://www.regulations.gov by searching for and 
locating Docket No. FAA-2020-0848.

Explanation of Requirements Bulletin

    The FAA worked in conjunction with industry, under the 
Airworthiness Directive Implementation Aviation Rulemaking Committee 
(AD ARC), to enhance the AD system. One enhancement is a process for 
annotating which steps in the service information are ``required for 
compliance'' (RC) with an AD. Boeing has implemented this RC concept 
into Boeing service bulletins.
    In an effort to further improve the quality of ADs and AD-related 
Boeing service information, a joint process improvement initiative was 
worked between the FAA and Boeing. The initiative resulted in the 
development of a new process in which the service information more 
clearly identifies the actions needed to address the unsafe condition 
in the ``Accomplishment Instructions.'' The new process results in a 
Boeing Requirements Bulletin, which contains only the actions needed

[[Page 59453]]

to address the unsafe condition (i.e., only the RC actions).

Interim Action

    The FAA considers this proposed AD interim action. The manufacturer 
is currently developing a modification that will address the unsafe 
condition identified in this AD. Once this modification is developed, 
approved, and available, the FAA might consider additional rulemaking.

Costs of Compliance

    The FAA estimates that this proposed AD affects 188 airplanes of 
U.S. registry. The FAA estimates the following costs to comply with 
this proposed AD:

                                      Estimated Costs for Required Actions
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                                                                                                 Cost on U.S.
             Action                     Labor cost          Parts cost     Cost per product        operators
----------------------------------------------------------------------------------------------------------------
Repetitive inspections.........  Up to 44 work-hours x                $0  Up to $3,740 per    Up to $703,120 per
                                  $85 per hour = Up to                     inspection cycle.   inspection cycle.
                                  $3,740 per inspection
                                  cycle.
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    The FAA has received no definitive data that would enable providing 
cost estimates for the on-condition actions specified in this proposed 
AD.

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) Will not affect intrastate aviation in Alaska, and
    (3) Will 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 removing Airworthiness Directive (AD) 
2007-07-03, Amendment 39-15003 (72 FR 14395, March 28, 2007), and 
adding the following new AD:

The Boeing Company: Docket No. FAA-2020-0848; Product Identifier 
2020-NM-088-AD.

(a) Comments Due Date

    The FAA must receive comments on this AD action by November 6, 
2020.

(b) Affected ADs

    This AD replaces AD 2007-07-03, Amendment 39-15003 (72 FR 14395, 
March 28, 2007).

(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 may deteriorate inside the tank due to excess heat from 
leaking trim air diffuser ducts or sidewall riser duct assemblies 
(collectively referred to as TADDs). This AD was also prompted by 
reports indicating that the high temperature composite material 
TADDs installed as specified in AD 2007-07-03 have also failed. 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.

(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, dated February 
18, 2020, do all applicable actions identified in, and in accordance 
with, the Accomplishment Instructions of Boeing Alert Requirements 
Bulletin 747-21A2577 RB, dated February 18, 2020.

    Note 1 to paragraph (g):  Guidance for accomplishing the actions 
required by this AD can be found in Boeing Alert Service Bulletin 
747-21A2577, dated February 18, 2020, which is referred to in Boeing 
Alert Requirements Bulletin 747-21A2577 RB, dated February 18, 2020.

(h) Exceptions to Service Information Specifications

    (1) Where Boeing Alert Requirements Bulletin 747-21A2577 RB, 
dated February 18, 2020, uses the phrase ``the original issue 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, 
dated February 18, 2020, 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 (j) of this AD.

(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

[[Page 59454]]

Requirements Bulletin 747-21A2577 RB, dated February 18, 2020, on 
any airplane.

(j) 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 local Flight Standards District 
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 (k)(1) of this AD. Information may be 
emailed to: 9-ANM-Seattle-ACO-AMOC-Requests@faa.gov.
    (2) Before using any approved AMOC, notify your appropriate 
principal inspector, or lacking a principal inspector, the manager 
of the local flight standards district office/certificate holding 
district 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.

(k) Related Information

    (1) For more information about this AD, contact Susan L. Monroe, 
Aerospace Engineer, Cabin Safety and Environmental Systems Section, 
FAA, Seattle ACO Branch, 2200 South 216th St., Des Moines, WA 98198; 
phone and fax: 206-231-3570; email: susan.l.monroe@faa.gov.
    (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 https://www.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 September 14, 2020.
Lance T. Gant,
Director, Compliance & Airworthiness Division, Aircraft Certification 
Service.
[FR Doc. 2020-20807 Filed 9-21-20; 8:45 am]
BILLING CODE 4910-13-P


