DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 39

[Docket No. FAA-2021-0614; Project Identifier AD-2021-00831-T;
Amendment 39-21677; AD 2021-16-15]
RIN 2120-AA64

Airworthiness Directives; The Boeing Company Airplanes

AGENCY: Federal Aviation Administration (FAA), DOT.

ACTION: Final rule; request for comments.

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SUMMARY: The FAA is adopting a new airworthiness directive (AD) for all
The Boeing Company Model 737-8, 737-9, and 737-8200 (737 MAX)
airplanes; and certain Model 737-800 and 737-900ER series airplanes.
This AD was prompted by the determination that the aft cargo
compartment fire suppression capability is reduced if the airplane is
dispatched or released with failed electronic flow control of air
conditioning packs, as is currently allowed by these airplane models'
master minimum equipment lists (MMELs). This AD prohibits the carriage
of cargo in the aft cargo compartment when the airplane is dispatched
or released with failed electronic flow control of air conditioning
packs. The FAA is issuing this AD to address the unsafe condition on
these products.

DATES: This AD is effective August 9, 2021.
The FAA must receive comments on this AD by September 23, 2021.

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.

Examining the AD Docket

You may examine the AD docket at https://www.regulations.gov by
searching for and locating Docket No. FAA-2021-0614; 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 final rule, any
comments received, and other information. The street address for Docket
Operations is listed above.

FOR FURTHER INFORMATION CONTACT: Sam Nalbandian, Aerospace Engineer,
Cabin Safety and Environmental Systems Section, FAA, Seattle ACO
Branch, 2200 South 216th St., Des Moines, WA 98198; phone and fax: 206-
231-3993; email: Samuel.K.Nalbandian@faa.gov.

SUPPLEMENTARY INFORMATION:

Background

The FAA was notified by Boeing in March 2021 of a potential concern
that the aft cargo compartment fire suppression capability is reduced
on affected airplanes if the airplane is dispatched or released with
failed electronic flow control of air conditioning packs, as is
currently allowed by the existing FAA-approved MMEL of the affected
airplane models. This MMEL allowance can result in the inability to
contain a fire in the aft cargo compartment due to increased air
leakage that degrades the fire suppression performance. A failed
electronic flow control of air conditioning packs would significantly
increase the pack airflow and cargo compartment air leakage. In April
2021, Boeing advised the FAA that such increased leakage could result
in insufficient concentration of Halon fire suppressant in the aft
cargo compartment, which can result in the inability to contain a fire
for the time necessary to divert to a suitable airport.
The FAA is issuing this AD to address failed electronic flow
control of air conditioning packs, which can result in an uncontained
aft cargo compartment fire due to insufficient cargo fire suppression
capability. The FAA is issuing this AD to address the unsafe condition
on these products.

FAA's Determination

The FAA is issuing this AD because the agency has determined the
unsafe condition described previously is likely to exist or develop in
other products of the same type design.

AD Requirements

This AD prohibits dispatch or release of an airplane with cargo in
the aft cargo compartment with failed electronic flow control of air
conditioning packs. The AD specifically allows non-combustible and/or
non-flammable empty cargo handling equipment, ballast, and/or fly-away
kits in the aft cargo compartment.

MMEL Revisions

This AD refers to items in ATA System No. 21, Air Conditioning, of
Boeing 737 (B-737-100/200/300/400/500/600/700/800/900/900ER) MMEL,
Revision 61, dated July 8, 2020; and Boeing 737 MAX (B-737-8/-8200/-9)
MMEL, Revision 3, dated April 12, 2021; ¹ those items may also be
included in an operator's FAA-approved minimum equipment list (MEL).
This AD prohibits dispatch or release of the airplane under conditions
currently allowed by those items in the MMEL. The FAA plans to revise
the MMELs to modify those items; operators would then be required to
also revise their applicable existing FAA-approved MEL accordingly.
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¹The MMEL items can be found in the applicable FAA-approved
MMEL, which can be found on the Flight Standards Information
Management System (FSIMS) website, https://fsims.faa.gov/PICResults.aspx?mode=Publication&doctype=MMELByModel.
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Justification for Immediate Adoption and Determination of the Effective
Date

Section 553(b)(3)(B) of the Administrative Procedure Act (APA) (5
U.S.C. 551 et seq.) authorizes agencies to dispense with notice and
comment procedures for rules when the agency, for ``good cause,'' finds
that those procedures are ``impracticable, unnecessary, or contrary to
the public interest.'' Under this section, an agency, upon finding good
cause, may issue a final rule without providing notice and seeking comment prior
to issuance. Further, section 553(d) of the APA authorizes agencies to
make rules effective in less than thirty days, upon a finding of good
cause.
An unsafe condition exists that requires the immediate adoption of
this AD without providing an opportunity for public comments prior to
adoption. The FAA has found that the risk to the flying public
justifies forgoing notice and comment prior to adoption of this rule
because failed electronic flow control of air conditioning packs can
result in an uncontained aft cargo compartment fire due to insufficient
cargo fire suppression capability. Accordingly, notice and opportunity
for prior public comment are impracticable and contrary to the public
interest pursuant to 5 U.S.C. 553(b)(3)(B).
In addition, the FAA finds that good cause exists pursuant to 5
U.S.C. 553(d) for making this amendment effective in less than 30 days,
for the same reasons the FAA found good cause to forgo notice and
comment.

Comments Invited

The FAA invites you to send any written data, views, or arguments
about this final rule. Send your comments to an address listed under
ADDRESSES. Include Docket No. FAA-2021-0614 and Project Identifier AD-
2021-00831-T at the beginning of your comments. The most helpful
comments reference a specific portion of the final rule, 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
this final rule 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
https://www.regulations.gov, including any personal information you
provide. The agency will also post a report summarizing each
substantive verbal contact received about this final rule.

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 AD 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 AD, 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 AD. Submissions containing CBI should be sent to Sam
Nalbandian, Aerospace Engineer, Cabin Safety and Environmental Systems
Section, FAA, Seattle ACO Branch, 2200 South 216th St., Des Moines, WA
98198; phone and fax: 206-231-3993; email: Samuel.K.Nalbandian@faa.gov.
Any commentary that the FAA receives that is not specifically
designated as CBI will be placed in the public docket for this
rulemaking.

Regulatory Flexibility Act

The requirements of the Regulatory Flexibility Act (RFA) do not
apply when an agency finds good cause pursuant to 5 U.S.C. 553 to adopt
a rule without prior notice and comment. Because the FAA has determined
that it has good cause to adopt this rule without notice and comment,
RFA analysis is not required.

Costs of Compliance

The FAA estimates that this AD affects 663 airplanes of U.S. registry.
The FAA has determined that revising the operator's existing FAA-
approved MEL, if accomplished in association with compliance for the
requirements of this AD, would take an average of 90 work-hours per
operator, although the agency recognizes that this number may vary from
operator to operator. Since operators typically incorporate MEL changes
for their affected fleets, the FAA has determined that a per-operator
estimate is more accurate than a per-airplane estimate. Therefore, the
FAA estimates the average total cost per operator to be $7,650 (90
work-hours x $85 per work-hour).

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

This AD will not have federalism implications under Executive Order
13132. This AD will 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 this AD:
(1) Is not a ``significant regulatory action'' under Executive
Order 12866, and
(2) Will not affect intrastate aviation in Alaska.

List of Subjects in 14 CFR Part 39

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

Adoption of the Amendment

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

PART 39--AIRWORTHINESS DIRECTIVES

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]

2. The FAA amends Sec. 39.13 by adding the following new airworthiness
directive: