DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 39

[Docket No. FAA-2022-1479; Project Identifier AD-2022-00703-T;
Amendment 39-22497; AD 2023-13-12]
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 adopting a new airworthiness directive (AD) for all
The Boeing Company Model 737-100, 737-200, 737-200C, 737-300, 737-400,
737-500, 737-600, 737-700, 737-700C, 737-800, 737-900, 737-900ER, 757-
200, 757-200PF, 757-200CB, 757-300, 767-200, 767-300, 767-300F, and
767-400ER series airplanes. This AD was prompted by reports indicating
premature aging of certain passenger chemical oxygen generators. This
AD requires repetitively replacing affected chemical oxygen generators
with serviceable parts. This AD also limits the installation of
affected parts. The FAA is issuing this AD to address the unsafe
condition on these products.

DATES: This AD is effective September 5, 2023.

ADDRESSES:
AD Docket: You may examine the AD docket at regulations.gov under
Docket No. FAA-2022-1479; 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 S. Tsang, Aviation Safety
Engineer, FAA, 2200 South 216th St., Des Moines, WA 98198; phone: 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 by adding an AD that would apply to all The Boeing Company
Model 737-100, 737-200, 737-200C, 737-300, 737-400, 737-500, 737-600,
737-700, 737-700C, 737-800, 737-900, 737-900ER, 757-200, 757-200PF,
757-200CB, 757-300, 767-200, 767-300, 767-300F, and 767-400ER series
airplanes. The NPRM published in the Federal Register on December 9,
2022 (87 FR 75528).
The NPRM was prompted by reports indicating premature aging of
certain passenger chemical oxygen generators. In the NPRM, the FAA
proposed to require repetitively replacing affected chemical oxygen
generators with serviceable parts, and to limit the installation of
affected parts. The FAA is issuing this AD to address the premature
aging that resulted in the chemical oxygen generators failing to
activate, which could fail to deliver oxygen during an emergency,
possibly resulting in injury to the airplane occupants.

Discussion of Final Airworthiness Directive

Comments

The FAA received comments from the Air Line Pilots Association,
International, and The Boeing Company. Both commenters supported the
NPRM without change.
The FAA received additional comments from Delta Air Lines, American
Airlines, United Airlines, and United Parcel Service. The following
presents the comments received on the NPRM and the FAA's response to
each comment.

Request To Clarify Service Life of Affected Parts

American Airlines requested clarification on why paragraph (i)(3)
of the proposed AD allows chemical oxygen generators to remain in
service longer than 10 years. American Airlines stated that paragraph
(i)(3) of the proposed AD contradicts paragraph (h) of the proposed AD
and leads to confusion.
The FAA agrees to clarify. Currently, there are units with a
manufacturing date older than 10 years that are potentially installed
on airplanes, and these units might be included in the group identified
in paragraph (i)(3) of this AD. After the initial replacement required
by paragraph (i)(3) of this AD, the introductory text to paragraph (i)
of this AD requires operators to replace affected units before
exceeding 10 years since date of manufacture. To determine the
appropriate compliance time for paragraph (i)(3) of this AD, the FAA
assessed the failure rate of the units, the number of suspect units,
and the probability of an unsafe outcome. The FAA has not changed this
AD in this regard.

Request To Remove the 30-Day Compliance Time for Inspection of Part
Numbers

American Airlines and Delta Air Lines requested removing the 30-day
compliance time for the inspection of the chemical oxygen generators
part numbers. American Airlines stated that inspecting the part numbers
alone does not provide any increase in safety and will severely disrupt
the regular maintenance of the airplane with the potential to impact
passengers if other work has to be postponed to meet a 30-day
inspection requirement. Instead of requiring the 6-, 12-, and 24-month
replacement, American Airlines suggested allowing 12 months to inspect
and correct the units. Delta Air Lines recommended allowing operators
to use existing methods to obtain chemical oxygen generator part
numbers and dates of manufacture at a time that works within the needs
of their operation rather than within 30 days. Delta Air Lines stated
that the existing methods have already been reviewed by the operators'
Certificate Management Office (CMO) and is FAA approved.
The FAA disagrees with the request to remove the 30-day compliance
time for the part number inspection. The FAA disagrees with Delta Air
Lines' recommendation to allow operators' existing methods to inspect
the chemical oxygen generators part numbers and date of manufacture
that work within the needs of their operation rather than within this
AD's compliance time. The FAA also disagrees with replacing this AD's
proposed compliance times with the American Airlines' proposed 12-month
compliance time to inspect and correct units. The commenter did not
provide justification to substantiate how a 12-month compliance time to
inspect and correct units provides an acceptable level of safety.
Passenger chemical oxygen generators identified in paragraph (i)(1) of
this AD must be replaced sooner than the proposed 12-month compliance
time. After considering all of the available information, the FAA
determined that the compliance time, as proposed, represents an
appropriate interval of time in which the required actions can be
performed in a timely manner within the affected fleet, while still
maintaining an adequate level of safety. When developing the compliance
time, the FAA considered the estimated hours to complete the inspection
and replacements and the availability of parts. There are provisions in
paragraph (g) of this AD that allow review of the airplane maintenance
records in lieu of an inspection, provided the date of manufacture can be conclusively
determined by that review. Under the provisions of paragraph (k) of
this AD, operators may apply for an extension of the compliance times
by providing rationale explaining why a compliance time extension
provides an acceptable level of safety. The FAA has not changed this AD
in this regard.

Request To Remove Inspection for Retired and Long-Term Storage
Airplanes

American Airlines requested that inspection of retired airplanes or
airplanes in long-term storage not be required until the airplane goes
into service.
The FAA agrees that operators are not required to inspect retired
airplanes because retired airplanes are not in service. And the FAA
agrees that airplanes in long-term storage are not required to comply
with the requirements of this AD until the airplane goes into service
(14 CFR 39.7). If the compliance time has passed before a stored
airplane is returned to service, it is not a violation. A violation
occurs only if a product is operated that does not meet the
requirements of an AD. Under the provisions of paragraph (k) of this
AD, an operator who is unable to accomplish the inspection in this AD
within the specified compliance time may request an alternative method
of compliance (AMOC) to extend this time. The FAA has not changed this
AD in this regard.

Request Six Months To Revise Manuals

American Airlines requested six months to revise applicable
manuals.
The FAA disagrees with the request to require six months to revise
applicable manuals. This AD requires only inspection of the chemical
oxygen generator part numbers and replacement of chemical oxygen
generators. This AD does not mandate revising applicable manuals. The
FAA has not changed this AD in this regard.

Request Six Months To Purge Inventory

American Airlines requested six months to purge inventory of P/N
117080-XX chemical oxygen generators.
The FAA disagrees with the request to require six months to purge
inventory of P/N 117080-XX chemical oxygen generators. This AD requires
only inspection of the chemical oxygen generator part numbers and
replacement of chemical oxygen generators. This AD does not mandate
purging inventory of P/N 117080-XX chemical oxygen generators. The FAA
has not changed this AD in this regard.

Request To Confirm Life Limit of AVOX Systems Part Number P/N 807218-03

American Airlines requested confirmation that FAA has determined
AVOX Systems part number (P/N) 807218-03 does not have the same
problems as P/N 117080-04 and continues to be an approved part number
with a life of 15 years from the date of manufacture. AVOX Systems P/N
807218-03 has been qualified to both Boeing Spec S417T401-44 (or Drager
P/N E71740-00) and Boeing Spec S417T401-60 (or Collins P/N 117080-04).
The FAA confirms that AVOX Systems P/N 807218-03 does not have the
same problems as P/N 117080-04. The life limit for AVOX Systems P/N
807218-03 is 15 years from the date of manufacture. Because this AD
does not address P/N 807218-03, no change to this AD is necessary.

Effect of Winglets on Accomplishment of the Proposed Actions

Aviation Partners Boeing stated that the installation of winglets
per Supplemental Type Certificate (STC) ST00830SE, STC ST01219SE, STC
ST01518SE, and STC ST01920SE on applicable Boeing models subject to the
proposed AD does not affect compliance with the mandated actions.
The FAA agrees with the commenter that STC ST00830SE, STC
ST01219SE, STC ST01518SE, and STC ST01920SE do not affect the ability
to accomplish the actions required by this AD. The FAA has not changed
this AD in this regard.

Request Use of Illustrated Parts Catalog To Determine Approved Part
Numbers

Delta Air Lines requested clarification on how to determine whether
a part number is approved. Paragraph (h)(2) of this AD does not have
any provision to allow operators to determine if a part number is
approved. Delta Air Lines assumed operators may use the airplane
Illustrated Parts Catalog (IPC) to determine acceptable approved
alternate parts.
The FAA confirms that operators may use the airplane IPC to
determine acceptable approved part numbers. The FAA has not changed
this AD in this regard.

Request To Define Acceptable Replacement Chemical Oxygen Generators

Delta Air Lines requested that paragraph (i) of the proposed AD be
revised to explicitly state that chemical oxygen generators be replaced
with serviceable units during the repetitive replacement.
The FAA agrees with the comment and has revised the introductory
text to paragraph (i) of this AD accordingly.

Request To Limit Replacement Requirement Based on Date of Manufacture

Delta Air Lines suggested that paragraph (i) of the proposed AD be
revised to state that no replacement is necessary for affected
passenger chemical oxygen generators that have a date of manufacture in
2014 or later. Delta inferred that since these generators would have a
manufacture date of 2014 or later, and therefore be within the new 10-
year life limit, replacement would not be mandated per the proposed AD.
The FAA disagrees that units that have a date of manufacture in
2014 or later need not be replaced. The FAA has added paragraph (i)(4)
of this AD to clarify that units with a date of manufacture in 2014 or
later must be replaced before exceeding 10 years since the date of
manufacture, with a 24-month grace period that will allow for timely
and orderly replacement of units that are close to their 10-year life
limit.

Request To Clarify Affected Airplanes

The United Parcel Service (UPS) Airlines requested limiting the
proposed AD to apply only to the affected airplane models with part
number 117080-02, 117080-03, or 117080-04 chemical oxygen generators
installed. The commenter noted that the proposed AD would require
accomplishment of paragraphs (g) and (i) on all of the airplane models
covered by paragraph (c) of the proposed AD, even if an applicable
airplane does not have part number 117080-02, 117080-03, or 117080-04
installed.
The FAA disagrees with the commenter's request. The FAA determined
that the part number 117080-02, 117080-03, or 117080-04 chemical oxygen
generators are rotable. This AD therefore applies to all airplanes of
the affected models to ensure that no person installs a non-serviceable
passenger chemical oxygen generator on an airplane that was initially
delivered with an acceptable unit, thereby subjecting that airplane to
the unsafe condition. The FAA has not changed this AD in this regard.

Additional Change to AD

The compliance time in paragraph (i)(1) of this AD has been
adjusted to accommodate airplanes with generators close to the 15-year
life limit as of the effective date of the AD. This change is not more
restrictive than what was proposed, and does not expand the
scope of the requirement as specified in the proposed AD.

Conclusion

The FAA reviewed the relevant data, considered any comments
received, and determined that air safety requires adopting this AD as
proposed. Accordingly, the FAA is issuing this AD to address the unsafe
condition on these products. Except for minor editorial changes, and
any other changes described previously, this AD is adopted as proposed
in the NPRM. None of the changes will increase the economic burden on
any operator.

Related Service Information

Collins Aerospace Service Information Letter (SIL) 117080-SIL-002,
dated May 4, 2022, specifies procedures for replacing affected chemical
oxygen generators.

Costs of Compliance

The FAA estimates that this AD affects 3,419 airplanes of U.S.
registry. The FAA estimates the following costs to comply with this AD:

Estimated Costs

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,
(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 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: