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2021-01-07 THE BOEING COMPANY: Amendment 39-21383; Docket No. FAA-2020-1109; Product Identifier 2020-NM-067-AD.
(a) EFFECTIVE DATE

    This airworthiness directive (AD) is effective March 9, 2021.

(b) AFFECTED ADS

    This  AD  affects  AD  2016-04-06,  Amendment  39-18400  (81  FR 9756,
    February 26, 2016) ("AD 2016-04-06").

(c) APPLICABILITY

    This AD applies to The Boeing Company Model 737-700 airplanes, certif-
    icated in any category, having line numbers (L/Ns) 481, 545, 684, 979,
    1089, 1211, and 1223.

(d) SUBJECT

    Air Transport Association (ATA) of America Code 2120, Air Distribution
    System.

(e) UNSAFE CONDITION

    This AD  was prompted  by a  determination that  a repetitive  test is
    needed to assess the components  on airplanes equipped with a  certain
    air distribution system configuration. The  FAA is issuing this AD  to
    address  latent  failures  of the  equipment  cooling  system and  low
    pressure environmental  control system,  which, in  combination with a
    cargo fire event, could result in smoke in the flight deck and/or main
    cabin, and possible loss of aircraft control.

(f) COMPLIANCE

    Comply with this AD within the compliance times specified,  unless al-
    ready done.

(g) REPETITIVE OPERATIONAL TESTS AND CORRECTIVE ACTIONS

    At the applicable times identified in paragraph 1.E.,  "Compliance" of
    Boeing Alert Service Bulletin 737-26A1137,  Revision 2,  dated January
    27, 2020, except as required by paragraph (i) of this AD,  do the test
    to verify correct operation of the smoke clearance mode  of the equip-
    ment cooling system and low pressure environmental control system, and
    do all applicable corrective actions,  in  accordance  with the Accom-
    plishment Instructions  of  Boeing Alert Service Bulletin 737-26A1137,
    Revision 2,  dated  January 27, 2020.  Do  all  applicable  corrective
    actions before further flight. Repeat the test thereafter at intervals
    not to exceed 9,000 flight hours.

(h) CONCURRENT REQUIREMENTS

    Before or concurrently with accomplishing the initial operational test
    required by paragraph (g) of this AD,  install  new relays  and change
    the wiring to the environmental control system, in accordance with the
    Accomplishment Instructions  of  Boeing  Alert  Service  Bulletin 737-
    26A1122, Revision 3, dated January 31, 2020. When the actions required
    by this paragraph are performed,  the installation  and changes speci-
    fied in paragraph 1.B. "Concurrent Requirements" of Boeing Alert Serv-
    ice Bulletin 737-26A1122 Revision 3, dated January 31, 2020, must also
    be done.

(i) EXCEPTIONS TO SERVICE INFORMATION SPECIFICATIONS

    Where  Boeing  Alert Service Bulletin 737-26A1137,  Revision 2,  dated
    January 27, 2020,  uses  the  phrase  "the R02 issue date  of  SB 737-
    26A1137," this AD requires using "the effective date of this AD."

(j) TERMINATING ACTION FOR AD 2016-04-06

    As of the effective date of this AD,  for the airplanes  identified in
    paragraph (c) of this AD only,  the requirements  of AD 2016-04-06 are
    terminated.

(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  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 identi-
    fied in paragraph  (l) 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 in-
    spector,  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.

(4) For service information  that  contains steps  that are labeled as Re-
    quired for Compliance (RC), the provisions of paragraphs (k)(4)(i) and
    (ii) of this AD apply.

(i) The steps labeled as RC,  including substeps  under an RC step and any
    figures identified in an RC step, must be done to comply with the  AD.
    If a step or substep is  labeled "RC Exempt," then the RC  requirement
    is removed  from that  step or  substep. An  AMOC is  required for any
    deviations to RC steps, including substeps and identified figures.

(ii) Steps not labeled as RC  may be  deviated from using accepted methods
     in accordance with the  operator's maintenance or inspection  program
     without  obtaining  approval  of  an  AMOC,  provided  the  RC steps,
     including  substeps  and identified  figures,  can still  be  done as
     specified,  and  the  airplane  can  be  put  back  in  an  airworthy
     condition.

(l) RELATED INFORMATION

    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.

(m) MATERIAL INCORPORATED BY REFERENCE

(1) The Director of the Federal Register  approved  the  incorporation  by
    reference (IBR) of the service information listed  in  this  paragraph
    under 5 U.S.C. 552(a) and 1 CFR part 51.

(2) You must use  this service information as applicable to do the actions
    required by this AD, unless the AD specifies otherwise.

(i) Boeing Alert Service Bulletin 737-26A1122,  Revision 3,  dated January
    31, 2020.

(ii) Boeing Alert Service Bulletin 737-26A1137, Revision 2,  dated January
     27, 2020.

(3) 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; tele-
    phone 562-797-1717; internet https://www.myboeingfleet.com.

(4) 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.

(5) You may view this service information  that is incorporated  by refer-
    ence at the National Archives and Records Administration  (NARA).  For
    information on the availability of this material at NARA, email fedreg
    .legal@nara.gov,  or go to: https://www.archives.gov/federal-register/
    cfr/ibr-locations.html.

Issued on December 30, 2020.  Lance T. Gant,  Director,  Compliance & Air-
worthiness Division, Aircraft Certification Service.

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.
PREAMBLE 

DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 39

[Docket No. FAA-2020-1109; Product Identifier 2020-NM-067-AD; Amendment
39-21383; AD 2021-01-07]
RIN 2120-AA64

Airworthiness Directives; The Boeing Company Airplanes

AGENCY: Federal Aviation Administration (FAA), DOT.

ACTION: Final rule; request for comments.

-----------------------------------------------------------------------

SUMMARY: The FAA is adopting a new airworthiness directive (AD) for
certain The Boeing Company Model 737-700 series airplanes. This AD
requires repetitive testing to verify correct operation of the smoke
clearance mode of the equipment cooling system and low pressure
environmental control system, and corrective actions if necessary. This
AD also requires installing new relays and changing the wiring to the
environmental control system, among other actions. This AD was prompted
by a determination that a repetitive test is needed to assess the
components on airplanes equipped with a certain air distribution system
configuration. The FAA is issuing this AD to address the unsafe
condition on these products.

DATES: This AD is effective March 9, 2021.
The Director of the Federal Register approved the incorporation by
reference of certain publications listed in this AD as of March 9,
2021.
The FAA must receive comments on this AD by April 8, 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.
For service information identified in this final rule, 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-
1109.

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-
1109; 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. 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:

Discussion

The FAA has determined that a repetitive test is needed to assess
the components on airplanes equipped with a certain air distribution
system configuration. A review by Boeing found that there was no
maintenance procedure available to assess the components used to
reconfigure the air distribution system to the cargo fire mode. Without
the repetitive test, failures of components could be latent for
extended periods. This condition, if not addressed, could result in
latent failures of the equipment cooling system and low pressure
environmental control system, which, in combination with a cargo fire
event, could result in smoke in the flight deck and/or main cabin, and
possible loss of aircraft control.

Other Related Rulemaking

The FAA issued AD 2016-04-06, Amendment 39-18400 (81 FR 9756,
February 26, 2016) (AD 2016-04-06), applicable to all The Boeing
Company Model 737-600, -700, -700C, -800, -900, and -900ER series
airplanes. That AD requires doing repetitive testing to verify correct
operation of the equipment cooling system and low pressure
environmental control system, and corrective actions if necessary. That
AD also requires, for certain airplanes, installing new relays and
changing the wiring to the environmental control system. That AD was
prompted by a determination that a repetitive test is needed to inspect
the components on airplanes equipped with a certain air distribution
system configuration. The actions required by that AD are intended to
address latent failures of the equipment cooling system and low
pressure environmental control system, which, in combination with a
cargo fire event, could result in smoke in the flight deck and/or main
cabin, and possible loss of aircraft control.
Since issuance of that AD, the FAA has determined that additional
actions are necessary to address the same unsafe condition identified
in AD 2016-04-06 for The Boeing Company Model 737-700 series airplanes
having line numbers (L/Ns) 481, 545, 684, 979, 1089, 1211, and 1223.
Those actions have been included in the revised service information
specified in paragraphs (g) and (h) of this AD. This AD adds the
requirements of paragraph (h) that include installing new relays and
changing the wiring to the environmental control system, and
accomplishing certain concurrent actions, for the affected airplanes.

Relationship Between This AD and AD 2016-04-06

This AD does not supersede AD 2016-04-06. Rather, the FAA has
determined that a stand-alone AD would be more appropriate to address
the requirements of this AD. AD 2016-04-06 did not address the unsafe
condition for the 7 airplanes mentioned previously and identified in
paragraph (c) of this AD. To address the unsafe condition for these 7
airplanes, this AD requires repetitive testing to verify correct
operation of the smoke clearance mode of the equipment cooling system
and low pressure environmental control system, and corrective actions
if necessary; and also requires installing new relays and changing the
wiring to the environmental control system, and accomplishing certain
concurrent actions. As such, this AD terminates all of the requirements
of AD 2016-04-06 for the airplanes identified in paragraph (c) of this
AD only.

Related Service Information Under 1 CFR Part 51

The FAA reviewed the following service information:
Boeing Alert Service Bulletin 737-26A1122, Revision 3, dated
January 31, 2020. This service information describes procedures for
installing new relays and changing the wiring to the environmental
control system.
Boeing Alert Service Bulletin 737-26A1137, Revision 2, dated
January 27, 2020. This service information describes procedures for
repetitive testing to verify correct operation of the smoke clearance
mode of the equipment cooling system and low pressure environmental
control system, and applicable corrective actions.
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 issuing 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.

AD Requirements

This AD requires accomplishing the actions specified in the service
information described previously.

FAA's Justification and Determination of the Effective Date

There are currently no domestic operators of these products.
Therefore, the FAA finds that notice and opportunity for prior public
comment are unnecessary and that good cause exists for making this
amendment effective in less than 30 days.

Comments Invited

This AD is a final rule that involves requirements affecting flight
safety and was not preceded by notice and an opportunity for public
comment. However, the FAA invites you to send any written data, views,
or arguments about this final rule. Send your comments to an address
listed under the ADDRESSES section. Include Docket No. FAA-2020-1109
and Product Identifier 2020-NM-067-AD at the beginning of your
comments. The FAA specifically invites comments on the overall
regulatory, economic, environmental, and energy aspects of this final
rule. 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, as well
as a report summarizing each substantive public contact with FAA
personnel concerning this AD. The FAA will consider all comments
received by the closing date for comments. The FAA may amend this AD
because of those comments.

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 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 that is not specifically designated as
CBI will be placed in the public docket for this rulemaking.

Regulatory Flexibility Act (RFA)

The requirements of the 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

Currently, there are no affected U.S.-registered airplanes. For any
affected airplane that is imported and placed on the U.S. Register in
the future, the FAA provides the following cost estimates to comply
with this AD:

Estimated Costs

Action Labor cost Parts cost Cost per product
Operational Test 4 work-hours x $85 per hour = $340 per test cycle $0 $340 per test cycle
New relays/wiring changes 104 work hours x $85 per hour = $8,840 11,417 $20,257

We estimate the following costs to do any necessary system fault
isolation and replacements that would be required based on the results
of the operational test. We have no way of determining the number of
aircraft that might need these actions:

On-Condition Costs

Action Labor cost Parts cost Cost per product
Perform system fault isolation and replace faulty component. 10 work-hours x $85 per hour = $850 $0 $850

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: