Rule2023-07034
Airworthiness Directives; The Boeing Company Airplanes
Primary source
Metadata and text below are from the Federal Register, a public-domain U.S. government work. Always verify the official published version before relying on it for any legal matter.
Published
April 5, 2023
Effective
May 10, 2023
Issuing agencies
Transportation DepartmentFederal Aviation Administration
Abstract
The FAA is adopting a new airworthiness directive (AD) for certain The Boeing Company Model 737-8, 737-9, and 737-8200 airplanes. This AD was prompted by a determination that new airworthiness limitations are necessary to require periodic replacement; or testing, and replacement if necessary; of the oxygen sensor of the nitrogen generation system (NGS). This AD requires revising the existing maintenance or inspection program, as applicable, to incorporate the new airworthiness limitations. The FAA is issuing this AD to address the unsafe condition on these products.
Full Text
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<title>Federal Register, Volume 88 Issue 65 (Wednesday, April 5, 2023)</title>
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[Federal Register Volume 88, Number 65 (Wednesday, April 5, 2023)]
[Rules and Regulations]
[Pages 20070-20073]
From the Federal Register Online via the Government Publishing Office [<a href="http://www.gpo.gov">www.gpo.gov</a>]
[FR Doc No: 2023-07034]
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DEPARTMENT OF TRANSPORTATION
Federal Aviation Administration
14 CFR Part 39
[Docket No. FAA-2022-1063; Project Identifier AD-2021-01339-T;
Amendment 39-22375; AD 2023-05-06]
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
certain The Boeing Company Model 737-8, 737-9, and 737-8200 airplanes.
This AD was prompted by a determination that new airworthiness
limitations are necessary to require periodic replacement; or testing,
and replacement if necessary; of the oxygen sensor of the nitrogen
generation system (NGS). This AD requires revising the existing
maintenance or inspection program, as applicable, to incorporate the
new airworthiness limitations. The FAA is issuing this AD to address
the unsafe condition on these products.
DATES: This AD is effective May 10, 2023.
The Director of the Federal Register approved the incorporation by
reference of certain publications listed in this AD as of May 10, 2023.
ADDRESSES:
AD Docket: You may examine the AD docket at <a href="http://regulations.gov">regulations.gov</a> under
Docket No. FAA-2022-1063; 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.
Material Incorporated by Reference:
<bullet> 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; website <a href="http://myboeingfleet.com">myboeingfleet.com</a>.
<bullet> 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 at
<a href="http://regulations.gov">regulations.gov</a> under Docket No. FAA-2022-1063.
FOR FURTHER INFORMATION CONTACT: Sam Dorsey, Aerospace Engineer,
Propulsion Section, FAA, Seattle ACO Branch, 2200 South 216th St., Des
Moines, WA 98198; phone and fax: 206-231-3415; email:
<a href="/cdn-cgi/l/email-protection#3043515d45555c1e5a1e545f42435549705651511e575f46"><span class="__cf_email__" data-cfemail="f281939f87979edc98dc969d8081978bb2949393dc959d84">[email protected]</span></a>.
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 certain The Boeing
Company Model 737-8, 737-9, and 737-8200 airplanes. The NPRM published
in the Federal Register on November 28, 2022 (87 FR 72902). The NPRM
was prompted by a determination that a new airworthiness limitation is
necessary to require periodic replacement of the oxygen sensor of the
NGS. In the NPRM, the FAA proposed to require revising the existing
maintenance or inspection program, as applicable, to incorporate the
new airworthiness limitation. The FAA is issuing this AD to prevent
increasing the flammability exposure of the center fuel tank, which
together with an ignition source in the fuel tank, could lead to a fuel
tank explosion and consequent loss of the airplane.
Discussion of Final Airworthiness Directive
Comments
The FAA received comments from the Air Line Pilots Association,
International (ALPA) and an individual who supported the NPRM without
change.
The FAA received additional comments from four commenters,
including Boeing, American Airlines, SIA Engineering Company, and
United Airlines (United). The following presents the comments received
on the NPRM and the FAA's response to each comment.
Request To Refer to Latest Service Information
Boeing and United requested that the proposed AD be revised to
specify compliance with Boeing 737-7/8/8200/9/10 Special Compliance
Items/Airworthiness Limitations, D626A011-9-04, dated May 2022, instead
of Boeing 737-7/8/8200/9/10 Special Compliance Items/Airworthiness
Limitations, D626A011-9-04, dated January 2019. Boeing noted that
Boeing 737-7/8/8200/9/10 Special Compliance Items/Airworthiness
Limitations, D626A011-9-04, dated May 2022 includes a revision to 47-
AWL-09 and the addition of new airworthiness limitation 47-AWL-10
(which is a Critical Design Configuration Control Limitation (CDCCL)
that specifies procedures for oxygen sensor repairs). Boeing added that
the revision to 47-AWL-09 provides additional options for operators
beyond replacing the oxygen sensor with a new oxygen sensor. Those
options include testing the installed NGS oxygen sensor using a
functional check described in the Airplane Maintenance Manual (AMM)
(and replacing if necessary), and replacing the oxygen sensor with an
NGS oxygen sensor repaired as specified in 47-AWL-10. United noted that
these changes provide operators with benefits necessary for the
efficient accomplishment of task 47-AWL-09.
The FAA partially agrees with the commenters' requests. Boeing 737-
7/8/8200/9/10 Special Compliance Items/Airworthiness Limitations,
D626A011-9-04, dated May 2022, provides options that are relieving, but
also includes a new CDCCL requirement that was not included in the
proposed AD. The FAA has therefore revised this AD to require
incorporating the information specified in AWL No. 47-AWL-09,
``Nitrogen Generation System--Oxygen Sensor,'' of Boeing 737-7/8/8200/
9/10 Special Compliance Items/Airworthiness Limitations, D626A011-9-04,
dated
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January 2019; or the information specified in 47-AWL-09 and 47-AWL-10
of Boeing 737-7/8/8200/9/10 Special Compliance Items/Airworthiness
Limitations, D626A011-9-04, dated May 2022.
Request To Refer to Latest Service Information
American Airlines requested that the FAA add a provision to
accomplish the oxygen sensor replacement with a repaired or overhauled
sensor instead of a brand new sensor. The commenter noted that this
provision would ease the burden on operators by not requiring them to
scrap used sensors and buy new ones. American Airlines added that the
737NG fleet has a similar AWL requirement, with a provision that a
repaired sensor may be installed.
The FAA agrees with the commenter's request. As noted previously,
this AD has been revised to allow incorporating the information in
Boeing 737-7/8/8200/9/10 Special Compliance Items/Airworthiness
Limitations, D626A011-9-04, dated May 2022, which includes provisions
for replacing the oxygen sensor with a repaired oxygen sensor or
testing the oxygen sensor, and replacing if necessary.
Request To Clarify Applicability
SIA Engineering Company asked that the FAA confirm the commenter's
understanding of paragraph (c) of the proposed AD. SIA Engineering
Company requested confirmation that the proposed AD does not affect The
Boeing Company Model 737-8, 737-9, and 737-8200 airplanes having
original airworthiness certificate or original export certificate of
airworthiness issued on or before April 1, 2021, and with a line number
not identified in paragraph (c)(2) of the proposed AD.
The FAA agrees to clarify. This AD applies to The Boeing Company
Model 737-8, 737-9, and 737-8200 airplanes having original
airworthiness certificate or original export certificate of
airworthiness issued on or before April 1, 2021, and it also applies to
The Boeing Company Model 737-8, 737-9, and 737-8200 airplanes with a
line number specified in paragraph (c)(2) of this AD. This AD does not
apply to any airplanes not specified in paragraph (c)(1) or (2) of this
AD.
Request To Revise a Sentence in the Background
Boeing requested that the FAA revise a sentence in the Background
section. In the NPRM the sentence reads ``Degraded performance by the
sensor could result in the [air separation module] ASM failing to
produce nitrogen-enriched air, and the fuel tank becoming more
flammable due to excessive oxygen-enriched air.'' Boeing stated that
this sentence is inaccurate because it implies a causality between a
failing oxygen sensor and a degrading ASM, when there is none. Boeing
added that the sentence further implies that the oxygen enriched air
(OEA) is redirected to the fuel tanks if the ASMs start going bad.
Boeing stated that the sentence should state: ``Degraded oxygen sensor
performance could result in the system failing to detect when the ASM
performance degrades below the acceptable threshold for nitrogen-
enriched air, and the fuel tank becoming more flammable due to
receiving poor-quality nitrogen-enriched air.''
The FAA agrees that there is no causality between the degraded
performance of the oxygen sensor and failure of ASM. Degradation of the
oxygen sensor performance does not directly result in the ASM failing
to produce nitrogen-enriched air, but rather it would result in a
failure to detect the condition of the ASM not performing at a required
level. However, the sentence in question from the Background section of
the NPRM will not be carried over to this final rule. Therefore, the
FAA has not changed this AD regarding this issue.
Request To Include Cost for Replacement Sensor
United requested that the NPRM be revised to include the cost of a
replacement NGS oxygen sensor and its availability.
The FAA disagrees with the commenter's request. This AD does not
require compliance with the maintenance actions specified in the AWL
items. Instead, this AD requires operators to revise their existing
maintenance or inspection program, as applicable, to incorporate the
new airworthiness limitations. Compliance with any airworthiness
limitation is required by 14 CFR 91.403(c). Therefore, compliance with
the AWLs is not a requirement of this AD, and including the cost of a
replacement part would be inappropriate. The FAA has not changed this
AD regarding this issue.
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 Under 1 CFR Part 51
The FAA reviewed Boeing 737-7/8/8200/9/10 Special Compliance Items/
Airworthiness Limitations, D626A011-9-04, dated January 2019. This
service information describes, among other airworthiness limitations
(AWLs), airworthiness limitation instruction (ALI) AWL No. 47-AWL-09,
``Nitrogen Generation System--Oxygen Sensor,'' for replacing oxygen
sensors.
The FAA also reviewed Boeing 737-7/8/8200/9/10 Special Compliance
Items/Airworthiness Limitations, D626A011-9-04, dated May 2022. This
service information describes, among other AWLs, ALI AWL No. 47-AWL-09,
``Nitrogen Generation System (NGS)--Oxygen Sensor,'' for replacement;
or testing, and replacement if necessary; of the oxygen sensor of the
nitrogen generation system (NGS), and AWL No. 47-AWL-10, ``Nitrogen
Generation System (NGS)--Oxygen Sensor Repair,'' for repairing oxygen
sensors.
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 ADDRESSES.
Costs of Compliance
The FAA estimates that this AD affects 62 airplanes of U.S.
registry. The FAA estimates the following costs to comply with this AD:
The FAA has determined that revising the existing maintenance or
inspection program takes an average of 90 work-hours per operator,
although the agency recognizes that this number may vary from operator
to operator. Since operators incorporate maintenance or inspection
program changes for their affected fleet(s), 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 workhour).
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
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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
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 adding the following new airworthiness
directive:
2023-05-06 The Boeing Company: Amendment 39-22375; Docket No. FAA-
2022-1063; Project Identifier AD-2021-01339-T.
(a) Effective Date
This airworthiness directive (AD) is effective May 10, 2023.
(b) Affected ADs
None
(c) Applicability
This AD applies to The Boeing Company Model 737-8, 737-9, and
737-8200 airplanes, certificated in any category, identified in
paragraphs (c)(1) and (2) of this AD.
(1) Airplanes with an original airworthiness certificate or
original export certificate of airworthiness issued on or before
April 1, 2021.
(2) Airplanes with line numbers 7668, 7678, and 7915.
(d) Subject
Air Transport Association (ATA) of America Code 28, Fuel.
(e) Unsafe Condition
This AD was prompted by significant changes made to
airworthiness limitations (AWLs) related to the nitrogen generation
system (NGS). The FAA is issuing this AD to prevent increasing the
flammability exposure of the center fuel tank, which together with
an ignition source in the fuel tank, could lead to a fuel tank
explosion and consequent loss of the airplane.
(f) Compliance
Comply with this AD within the compliance times specified,
unless already done.
(g) Maintenance or Inspection Program Revision
Within 60 days after the effective date of this AD, revise the
existing maintenance or inspection program, as applicable, to
incorporate the information specified in AWL No. 47-AWL-09,
``Nitrogen Generation System--Oxygen Sensor,'' of Boeing 737-7/8/
8200/9/10 Special Compliance Items/Airworthiness Limitations,
D626A011-9-04, dated January 2019; or the information specified in
AWL No. 47-AWL-09, ``Nitrogen Generation System (NGS)--Oxygen
Sensor,'' and AWL No. 47-AWL-10, ``Nitrogen Generation System
(NGS)--Oxygen Sensor Repair,'' of Boeing 737-7/8/8200/9/10 Special
Compliance Items/Airworthiness Limitations, D626A011-9-04, dated May
2022. The initial compliance time for accomplishing task AWL No. 47-
AWL-09 is: Within 18,000 flight hours after the date of issuance of
the original airworthiness certificate or the original export
certificate of airworthiness, within 18,000 flight hours after the
most recent replacement or test was performed as specified in AWL
No. 47-AWL-09, or within 12 months after the effective date of this
AD, whichever is latest.
(h) No Alternative Actions, Intervals, or Critical Design Configuration
Control Limitations (CDCCLs)
After the existing maintenance or inspection program has been
revised as required by paragraph (g) of this AD, no alternative
actions (e.g., inspections), intervals, or CDCCLs may be used unless
the actions, intervals, and CDCCLs are approved as an alternative
method of compliance (AMOC) in accordance with the procedures
specified in paragraph (i) of this AD.
(i) 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 responsible Flight Standards 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 (j) of this AD. Information may be emailed
to: <a href="/cdn-cgi/l/email-protection#685145292625453b0d091c1c040d45292b27452925272b453a0d191d0d1b1c1b280e0909460f071e"><span class="__cf_email__" data-cfemail="94adb9d5dad9b9c7f1f5e0e0f8f1b9d5d7dbb9d5d9dbd7b9c6f1e5e1f1e7e0e7d4f2f5f5baf3fbe2">[email protected]</span></a>.
(2) Before using any approved AMOC, notify your appropriate
principal inspector, or lacking a principal inspector, the manager
of the responsible Flight Standards 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.
(j) Additional Information
For more information about this AD, contact Sam Dorsey,
Aerospace Engineer, Propulsion Section, FAA, Seattle ACO Branch,
2200 South 216th St., Des Moines, WA 98198; phone and fax: 206-231-
3415; email: <a href="/cdn-cgi/l/email-protection#6c1f0d0119090042064208031e1f09152c0a0d0d420b031a"><span class="__cf_email__" data-cfemail="aad9cbc7dfcfc684c084cec5d8d9cfd3eacccbcb84cdc5dc">[email protected]</span></a>.
(k) 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 737-7/8/8200/9/10 Special Compliance Items/
Airworthiness Limitations, D626A011-9-04, dated January 2019.
(ii) Boeing 737-7/8/8200/9/10 Special Compliance Items/
Airworthiness Limitations, D626A011-9-04, dated May 2022.
(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; telephone 562-797-1717; website <a href="http://myboeingfleet.com">myboeingfleet.com</a>.
(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 reference at the National Archives and Records Administration
(NARA). For information on the availability of this material at
NARA, <a href="/cdn-cgi/l/email-protection#9cfaeeb2f5f2efecf9ffe8f5f3f2dcf2fdeefdb2fbf3ea"><span class="__cf_email__" data-cfemail="90f6e2bef9fee3e0f5f3e4f9fffed0fef1e2f1bef7ffe6">[email protected]</span></a>, or go to: <a href="http://www.archives.gov/federal-register/cfr/ibr-locations.html">www.archives.gov/federal-register/cfr/ibr-locations.html</a>.
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Issued on March 5, 2023.
Christina Underwood,
Acting Director, Compliance & Airworthiness Division, Aircraft
Certification Service.
[FR Doc. 2023-07034 Filed 4-4-23; 8:45 am]
BILLING CODE 4910-13-P
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