DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 39

[Docket No. FAA-2019-0480; Product Identifier 2019-NM-041-AD; Amendment
39-21498; AD 2021-08-04]
RIN 2120-AA64

Airworthiness Directives; The Boeing Company Airplanes

AGENCY: Federal Aviation Administration (FAA), DOT.

ACTION: Final rule.

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SUMMARY: The FAA is superseding Airworthiness Directive (AD) 2013-07-
09, which applied to certain The Boeing Company Model 737-700, -700C, -
800, and -900ER series airplanes, Model 747-400F series airplanes, and
Model 767-200 and -300 series airplanes. AD 2013-07-09 required a
general visual inspection for affected serial numbers of the crew
oxygen mask stowage box units, and replacement or re-identification as
necessary. This AD retains the requirements of AD 2013-07-09 and
expands the applicability. This AD was prompted by a determination that
the affected parts may be installed on airplanes outside the original
applicability of AD 2013-07-09. The FAA is issuing this AD to address
the unsafe condition on these products.

DATES: This AD is effective May 26, 2021.
The Director of the Federal Register approved the incorporation by
reference of certain publications listed in this AD as of May 20, 2013
(78 FR 22178, April 15, 2013).

ADDRESSES: For Boeing 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. For Intertechnique service information
identified in this final rule, contact Aerotechnics, 61 rue Pierre
Curie BP 1, 78373 Plaisir, CEDEX, France; phone: +33 1 6486 6964;
internet https://www.zodiacaerospace.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-2019-0480.

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-2019-
0480; 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
address for Docket Operations is U.S. Department of Transportation,
Docket Operations, M-30, West Building Ground Floor, Room W12-140, 1200
New Jersey Avenue SE, Washington, DC 20590.

FOR FURTHER INFORMATION CONTACT: Nicole 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: Nicole.S.Tsang@faa.gov.

SUPPLEMENTARY INFORMATION:

Background

The FAA issued a notice of proposed rulemaking (NPRM) to amend 14
CFR part 39 to supersede AD 2013-07-09, Amendment 39-17413 (78 FR
22178, April 15, 2013) (AD 2013-07-09). AD 2013-07-09 applied to
certain The Boeing Company Model 737-700, -700C, -800, and -900ER
series airplanes, Model 747-400F series airplanes, and Model 767-200
and -300 series airplanes. The NPRM published in the Federal Register
on June 25, 2019 (84 FR 29818). The NPRM was prompted by reports
indicating that certain crew oxygen mask stowage box units were
possibly delivered with a burr in the inlet fitting. The burr might
break loose during test or operation, and might pose an ignition source
or cause an inlet valve to jam. The NPRM was also prompted by a
determination that the affected parts may be installed on airplanes
outside the original applicability of AD 2013-07-09. The NPRM proposed
to continue to require a general visual inspection for affected serial
numbers of the crew oxygen mask stowage box units, and replacement or
re-identification as necessary. The NPRM also proposed to expand the
applicability to include those other airplanes. The FAA is issuing this
AD to address this possible ignition source, which could result in an
oxygen-fed fire; or an inlet valve jam in a crew oxygen mask stowage
box unit, which could result in restricted flow of oxygen.
The FAA issued a supplemental NPRM (SNPRM) that published in the
Federal Register on November 5, 2020 (85 FR 70526). The SNPRM proposed
to continue to require a general visual inspection for affected serial
numbers of the crew oxygen mask stowage box units, and replacement or
re-identification as necessary. The SNPRM also proposed to expand the
applicability to include additional airplane models.

Comments

The FAA gave the public the opportunity to participate in
developing this AD. The following presents the comments received on the
SNPRM and the FAA's response to each comment.

Support for the SNPRM

The Air Line Pilots Association, International (ALPA) and Boeing
expressed support for the SNPRM. Additional comments from ALPA are
addressed below.

Effect of Winglets on Accomplishment of the Proposed Actions

Aviation Partners Boeing stated that the installation of blended or
split scimitar winglets per Supplemental Type Certificate (STC)
ST01219SE on Model 737CL airplanes (Model 737-200, -300, -400, and -500
series airplanes), and blended winglets per STC ST01518SE on Model 757
airplanes, does not affect the accomplishment of the manufacturer's
service instructions.
The FAA agrees with the commenter that STC ST01219SE and STC
ST01518SE do not affect the accomplishment of the manufacturer's
service instructions. Therefore, the installation of STC ST01219SE or
STC ST01518SE does not affect the ability to accomplish the actions
required by this AD. The FAA has not changed this AD in this regard.

Request To Shorten the Compliance Time

ALPA requested that the FAA shorten the compliance time of the
proposed AD from 24 months to 12 months. ALPA noted that several
commenters on the NPRM requested an extended compliance time, and that
it is not in favor of an extension.
The FAA disagrees with the commenter's request. ALPA did not
provide justification for its request. As noted in the SNPRM, in
developing an appropriate compliance time for this action, the FAA
considered the safety implications, parts availability, and normal
maintenance schedules for the timely accomplishment of the inspection
and replacement or re-identification as necessary. Further, operators
are always permitted to accomplish the requirements of an AD at a time
earlier than the specified compliance time. In addition, to reduce the
compliance time of the proposed AD would necessitate (under the
provisions of the Administrative Procedure Act) reissuing the notice,
reopening the period for public comment, considering additional
comments subsequently received, and eventually issuing a final rule.
That procedure could add unwarranted time to the rulemaking process. In
light of this, and in consideration of the amount of time that has
already elapsed since issuance of the original notice, the FAA has
determined that further delay of this AD is not appropriate. The FAA
has not changed this AD in this regard.

Request To Allow a Records Review Based on Certain Additional Criteria

United Parcel Service Co. (UPS) requested that the introductory
text to paragraph (i) of the proposed AD be revised to allow a records
review in lieu of the specified inspection, provided it can be
conclusively determined that the serial number is not an affected
(suspect) part (one that is identified in the Appendix of
Intertechnique Service Bulletin MXP1/4-35-175, Revision 2, dated May
10, 2011). UPS noted that paragraph (i) of the proposed AD would allow
a records review if the serial number of the crew oxygen mask stowage
box unit could be conclusively determined. UPS noted that it has
identified scenarios where the serial number may not be conclusively
known, but the unit can be confirmed to not be one of the affected
units. UPS explained that Boeing was not consistent in providing serial
numbers for the units with delivery documents. However, UPS noted that
through records showing when units were changed, as well as knowing the
date of production of a given aircraft, UPS can conclusively determine
that the units with the affected serial numbers were not installed on a
given aircraft.
The FAA agrees with the commenter's request for the reasons
provided. The FAA has revised the introductory text to paragraph (i) of
this AD to clarify that a records review is also acceptable if it can
be conclusively determined that the serial number is not one that is
identified in the Appendix of Intertechnique Service Bulletin MXP1/4-
35-175, Revision 2, dated May 10, 2011.

Request To Revise Manufacturing Date Range

United Airlines requested that paragraph (i)(1) of the proposed AD
be revised to specify that units with a manufacturing date outside the
range of July 2007 through November 2007 inclusive (instead of July 12,
2007, through November 20, 2007, inclusive) do not need to be replaced.
United Airlines also requested that similar revisions be made to the
introductory text to paragraph (i) of the proposed AD, and paragraphs
(i)(2), (j)(1), and (j)(2) of the proposed AD. United Airlines stated
that the manufacture date on the mask stowage box units typically shows
only the month and year (in MMYYYY format). The commenter noted that
determining the exact calendar date of manufacture may not be possible,
and without a specific serial number, the manufacturer would not be
able to narrow down the date.
The FAA partially agrees with the commenter's request. The FAA
agrees that determining the exact date of manufacture may not be
possible because the manufacturer date on the mask stowage box units
typically shows only the month and year. The FAA has therefore revised
paragraph (i)(1) of this AD to specify that units with a manufacturing
date outside the range of July 2007 through November 2007 inclusive do
not need to be replaced. The FAA has also revised paragraph (j)(1) of
this AD to specify that units where the serial number is unreadable or
undetermined, but the manufacturing date can conclusively be determined
to be outside the range of July 2007 through November 2007 inclusive,
may be installed on an airplane. However, the FAA has determined that
the commenter's suggested revisions to the introductory text to
paragraph (i) of this AD are not needed because the introductory text
to paragraph (i) of this AD only requires determining the serial number
and does not specify actions based on whether or not the serial number
can be determined. In addition, the FAA has determined that the
commenter's suggested revisions to paragraphs (i)(2) and (j)(2) of this
AD are not needed because the actions in those paragraphs are only
applicable for units with a known serial number that is identified in
table 2 of the Appendix of Intertechnique Service Bulletin MXP1/4-35-
175, Revision 2, dated May 10, 2011 (those that need re-
identification).

Request To Allow Use of Aircraft Maintenance Manual (AMM)

Delta Air Lines (Delta) requested confirmation that it may use the
respective fleet's AMM to perform removals and installations if any of
the affected units are found on its airplanes. Delta noted that
paragraph (i) of the proposed AD does not specify instructions for
removal or replacement. Delta asked for confirmation that using the
applicable AMM for these tasks would not require it to obtain an
alternative method of compliance (AMOC).
The FAA agrees that the commenter's intended approach is acceptable
for compliance with this AD and that no AMOC is needed to use the
applicable AMM. The AMMs for the affected airplanes contain adequate
instructions for removal and installation of the affected units. No
change to this AD is necessary.

Clarification of Certain Actions

The FAA has revised paragraph (i)(1) of this AD to clarify
conditions that require replacement of a crew oxygen mask stowage box
unit, which includes an unreadable or undetermined serial number,
except as otherwise specified.
The FAA has also revised paragraph (j)(1) of this AD to clarify
conditions that prohibit the installation of a crew oxygen mask stowage
box unit, which includes an unreadable or undetermined serial number,
except as specified otherwise.

Conclusion

The FAA reviewed the relevant data, considered the comments
received, and determined that air safety and the public interest
require adopting this AD with the changes described previously, and
minor editorial changes. The FAA has determined that these minor
changes:

Are consistent with the intent that was proposed in the
SNPRM for addressing the unsafe condition; and
Do not add any additional burden upon the public than was
already proposed in the SNPRM.
The FAA also determined that these changes will not increase the
economic burden on any operator or increase the scope of this AD.

Related Service Information Under 1 CFR Part 51

This AD requires Boeing Alert Service Bulletin 737-35A1121,
Revision 1, dated November 7, 2011; Boeing Alert Service Bulletin 747-
35A2126, Revision 1, dated September 29, 2011; Boeing Alert Service
Bulletin 767-35A0057, Revision 1, dated November 17, 2011; and
Intertechnique Service Bulletin MXP1/4-35-175, Revision 2, dated May
10, 2011; which the Director of the Federal Register approved for
incorporation by reference as of May 20, 2013 (78 FR 22178, April 15,
2013). 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.

Costs of Compliance

The FAA estimates that this AD affects 3,723 airplanes of U.S.
registry. The FAA estimates the following costs to comply with this AD:

Estimated Costs

The FAA has received no definitive data that would enable providing
cost estimates for the on-condition actions specified in this 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 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,
(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.

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

a. Removing Airworthiness Directive (AD) 2013-07-09, Amendment 39-17413
(78 FR 22178, April 15, 2013); and

b. Adding the following new AD: