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Rule2023-26367

Airworthiness Directives; The Boeing Company Airplanes

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Published

November 30, 2023

Effective

December 15, 2023

Issuing agencies

Transportation DepartmentFederal Aviation Administration

Abstract

The FAA is adopting a new airworthiness directive (AD) for all The Boeing Company Model 747 airplanes. This AD was prompted by reports of latent failures of the lightning protection features for the engine fuel feed system. This AD requires an inspection for damage and a measurement of the electrical bonding resistance of the out-tank fuel feed tube bonding jumper in the strut for each of the four engines, a measurement of the electrical bonding resistance of the forward side of the front spar bulkhead fitting adapter for each of the four engines, and applicable related investigative and corrective actions. 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 229 (Thursday, November 30, 2023)</title>
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[Federal Register Volume 88, Number 229 (Thursday, November 30, 2023)]
[Rules and Regulations]
[Pages 83494-83498]
From the Federal Register Online via the Government Publishing Office [<a href="http://www.gpo.gov">www.gpo.gov</a>]
[FR Doc No: 2023-26367]

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DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 39

[Docket No. FAA-2023-2228; Project Identifier AD-2023-01095-T;
Amendment 39-22616; AD 2023-23-14]
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 747 airplanes. This AD was prompted by reports
of latent failures of the lightning protection features for the engine
fuel feed system. This AD requires an inspection for damage and a
measurement of the electrical bonding resistance of the out-tank fuel
feed tube bonding jumper in the strut for each of the four engines, a
measurement of the electrical bonding resistance of the forward side of
the front spar bulkhead fitting adapter for each of the four engines,
and applicable related investigative and corrective actions. The FAA is
issuing this AD to address the unsafe condition on these products.

DATES: This AD is effective December 15, 2023.
The Director of the Federal Register approved the incorporation by
reference of certain publications listed in this AD as of December 15,
2023.
The FAA must receive comments on this AD by January 16, 2024.

ADDRESSES: You may send comments, using the procedures found in 14 CFR
11.43 and 11.45, by any of the following methods:
<bullet> Federal eRulemaking Portal: Go to <a href="http://regulations.gov">regulations.gov</a>. Follow
the instructions for submitting comments.
<bullet> Fax: 202-493-2251.
<bullet> 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.
<bullet> Hand Delivery: Deliver to Mail address above between 9
a.m. and 5 p.m., Monday through Friday, except Federal holidays.
AD Docket: You may examine the AD docket at <a href="http://regulations.gov">regulations.gov</a> by
searching for and locating Docket No. FAA-2023-2228; 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.
Material Incorporated by Reference:
<bullet> For Boeing material 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 referenced material 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> by searching for and locating Docket No. FAA-2023-2228.

FOR FURTHER INFORMATION CONTACT: Samuel Dorsey, Aviation Safety
Engineer, FAA, 2200 South 216th St., Des Moines, WA 98198; phone: 206-
231-3415; email: <a href="/cdn-cgi/l/email-protection#df8cbeb2aabab3f1b5f1bbb0adacbaa69fb9bebef1b8b0a9">[email&#160;protected]</a>.

SUPPLEMENTARY INFORMATION:

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-2023-2228 and Project Identifier AD-
2023-01095-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

[[Page 83495]]

information as described in 14 CFR 11.35, the FAA will post all
comments received, without change, to <a href="http://regulations.gov">regulations.gov</a>, 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 Samuel
Dorsey, Aviation Safety Engineer, FAA, 2200 South 216th St., Des
Moines, WA 98198; phone: 206-231-3415; email: <a href="/cdn-cgi/l/email-protection#7724161a02121b591d5913180504120e3711161659101801">[email&#160;protected]</a>.
Any commentary that the FAA receives that is not specifically
designated as CBI will be placed in the public docket for this
rulemaking.

Background

The electrical bonding of the engine fuel feed tube penetrating the
fuel tanks of Boeing Model 747-8 series airplanes and other models is
the primary design feature to prevent the development of an ignition
source inside the fuel tank during a lightning strike to the engine
nacelle. The fuel feed lightning protection features include the spar
fitting that redirects the majority of current during a lightning
event. A separate bonding jumper outside the fuel tank provides a
second electrical path for current from lightning strikes. The
encapsulation sealant over the fuel tank wall fitting inside the fuel
tank provides additional protection.
However, Boeing has recently discovered that the bonding jumper
outside the fuel tank is failing at an excessive rate in addition to
the known degradation of the primary electrical bonding path through
the spar fitting. Furthermore, Boeing has reported finding a complete
crack around the circumference of the fuel feed fitting encapsulation
inside a fuel tank of a Model 747-8 series airplane. This encapsulation
is designed to isolate any sparks/arcing generated during a lightning
strike because of failed electrical bonds from flammable fuel vapors in
the tank. This is an urgent safety issue, as all fuel feed lightning
protection features now have evidence of compromise. The FAA has
determined that all Model 747 airplanes are affected by the unsafe
condition.
A lightning strike to an engine nacelle combined with a latent
failure of the lightning protection features for the engine fuel feed
system, if not addressed, could result in the potential for ignition
sources inside fuel tanks, which, in combination with flammable fuel
vapors, could result in a fuel tank explosion and consequent loss of
the airplane. 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.

Related Service Information Under 1 CFR Part 51

The FAA reviewed the following service information. These documents
are distinct since they apply to different airplane models.
<bullet> For Model 747-8 and 747-8F series airplanes: Boeing Multi
Operator Message MOM-MOM-23-0885-01B-R1, dated November 13, 2023.
<bullet> For Model 747-400, 747-400D, and 747-400F series
airplanes: Boeing Multi Operator Message MOM-MOM-23-0899-01B-R1, dated
November 13, 2023. (For the 747-400D, see the Differences Between this
AD and the Service Information section below.)
<bullet> For Model 747-100, 747-100B, 747-100B SUD, 747-200B, 747-
200C, 747-200F, 747-300, 747SR, and 747SP series airplanes: Boeing
Multi Operator Message MOM-MOM-23-0907-01B, dated November 13, 2023.
This service information specifies procedures for a detailed
inspection for damage and a measurement of the electrical bonding
resistance of the out-tank fuel feed tube bonding jumper in the strut
for each of the four engines, and a measurement of the electrical
bonding resistance of the forward side of the front spar bulkhead
fitting adapter for each of the four engines. The detailed inspection
for damage includes making sure the bonding jumper installation is
secure.
This service information also specifies related investigative
actions, which include, depending on the airplane configuration, a
general visual inspection of the aft side of the front spar to identify
the configuration of the fuel feed tube and bulkhead fitting adapter, a
detailed inspection for damage and measurements of the electrical
bonding resistance of the in-tank bonding jumper, a general visual
inspection of the wet-side front spar bulkhead fitting adapter for
missing and damaged sealant or for missing sealant and damage to the
encapsulation seal, and a general visual inspection of the seal for the
welded tube fitting configuration for missing and damaged sealant.
This service information also specifies corrective actions, which
include, depending on the airplane configuration, adjusting the
installation and reworking the bonding jumper bonding path, replacement
of the bonding jumper; and re-installing the front spar bulkhead
fitting and applying sealant.
This service information also specifies reporting findings of the
inspections and measurements to Boeing.
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.

AD Requirements

This AD requires an inspection for damage and a measurement of the
electrical bonding resistance of the out-tank fuel feed tube bonding
jumper in the strut for each of the four engines, a measurement of the
electrical bonding resistance of the forward side of the front spar
bulkhead fitting adapter for each of the four engines, applicable
related investigative and corrective actions, and reporting inspection
and measurement findings to Boeing.

Differences Between This AD and the Service Information

For Boeing Multi Operator Message MOM-MOM-23-0899-01B-R1, dated
November 13, 2023, which applies to Model 747-400 and 747-400F series
airplanes, the FAA has determined that Model 747-400D airplanes can
also accomplish the required actions using that service information.
Model 747-400D airplanes are similar in design to Model 747-400 and
747-400F series airplanes.

Interim Action

This AD is considered to be interim action. The inspection reports
that are required by this AD will enable the manufacturer to obtain
better insight into the nature, cause, and extent of the bonding
degradation and failures, and eventually to develop final action to

[[Page 83496]]

address the unsafe condition. Once final action has been identified,
the FAA might consider further rulemaking.

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 the lightning protection features for the engine fuel feed
system could fail without being detected. This could result in no
lightning protection features remaining due to the latent failure. A
lightning strike to an engine nacelle, in combination with flammable
fuel vapors, could result in a fuel tank explosion and consequent loss
of the airplane. 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.

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 211 airplanes of U.S.
registry. The FAA estimates the following costs to comply with this AD:

Estimated Costs
----------------------------------------------------------------------------------------------------------------
Cost on U.S.
Action Labor cost Parts cost Cost per product operators
----------------------------------------------------------------------------------------------------------------
Inspections/measurements of the Up to 6 work-hours $0 Up to $510 per Up to $107,610 per
out-tank bonding jumper and x $85 per hour = inspection/ inspection/
front spar bulkhead fitting Up to $510 per measurement cycle. measurement cycle.
adapter. inspection/
measurement cycle.
Reporting........................ 1 work-hour x 85 0 85 per inspection/ 85 per inspection/
per hour = 85 per measurement cycle. measurement cycle.
inspection/
measurement cycle.
----------------------------------------------------------------------------------------------------------------

The FAA estimates the following costs to do any necessary related
investigative and corrective actions that would be required based on
the results of the inspections/measurements. The FAA has no way of
determining the number of aircraft that might need these actions:

On-Condition Costs
------------------------------------------------------------------------
Action Labor cost Parts cost
------------------------------------------------------------------------
Related Investigative Actions.. Up to 2 work-hours $0.
x $85 per hour =
$170.
Corrective Actions............. Up to 34 work- Up to 1,000.
hours x 85 per
hour = 2,890.
------------------------------------------------------------------------

Paperwork Reduction Act

A federal agency may not conduct or sponsor, and a person is not
required to respond to, nor shall a person be subject to a penalty for
failure to comply with a collection of information subject to the
requirements of the Paperwork Reduction Act unless that collection of
information displays a currently valid OMB Control Number. The OMB
Control Number for this information collection is 2120-0056. Public
reporting for this collection of information is estimated to be
approximately 1 hour per response, including the time for reviewing
instructions, searching existing data sources, gathering and
maintaining the data needed, completing and reviewing the collection of
information. All responses to this collection of information are
mandatory. Send comments regarding this burden estimate or any other
aspect of this collection of information, including suggestions for
reducing this burden to: Information Collection Clearance Officer,
Federal Aviation Administration, 10101 Hillwood Parkway, Fort Worth, TX
76177-1524.

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.

[[Page 83497]]

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.

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:

2023-23-14 The Boeing Company: Amendment 39-22616; Docket No. FAA-
2023-2228; Project Identifier AD-2023-01095-T.

(a) Effective Date

This airworthiness directive (AD) is effective December 15,
2023.

(b) Affected ADs

None.

This AD applies to all The Boeing Company Model 747-100, 747-
100B, 747-100B SUD, 747-200B, 747-200C, 747-200F, 747-300, 747-400,
747-400D, 747-400F, 747SR, 747SP, 747-8F, and 747-8 series
airplanes, certificated in any category.

(d) Subject

Air Transport Association (ATA) of America Code 28, Fuel.

(e) Unsafe Condition

This AD was prompted by reports of latent failures of the
lightning protection features for the engine fuel feed system. The
FAA is issuing this AD to address latent failures of the lightning
protection features for the engine fuel feed system. A lightning
strike to an engine nacelle combined with latent failures of the
lightning protection features for the engine fuel feed system, if
not addressed, could result in the potential for ignition sources
inside fuel tanks, which, in combination with flammable fuel vapors,
could result in 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) Repetitive Inspections/Measurements, Related Investigative, and
Corrective Actions

Within 90 days after the effective date of this AD for Model 747
airplanes operated in a passenger configuration, and within 120 days
after the effective date of this AD for Model 747 airplanes operated
in an all-cargo configuration: Do a detailed inspection for damage
and measure the electrical bonding resistance of the out-tank fuel
feed tube bonding jumper in the strut for each of the four engines,
measure the electrical bonding resistance of the forward side of the
front spar bulkhead fitting adapter for each of the four engines,
and do all applicable related investigative and corrective actions,
in accordance with Part 2 of the applicable Boeing multi operator
message specified in paragraphs (g)(1) through (3) of this AD. Do
all applicable related investigative and corrective actions before
further flight. Repeat the inspection and measurements thereafter at
intervals not to exceed 12 months.
(1) For Model 747-8 and 747-8F series airplanes: Boeing Multi
Operator Message MOM-MOM-23-0885-01B-R1, dated November 13, 2023.
(2) For Model 747-400, 747-400D, and 747-400F series airplanes:
Boeing Multi Operator Message MOM-MOM-23-0899-01B-R1, dated November
13, 2023.
(3) For Model 747-100, 747-100B, 747-100B SUD, 747-200B, 747-
200C, 747-200F, 747-300, 747SR, and 747SP series airplanes: Boeing
Multi Operator Message MOM-MOM-23-0907-01B, dated November 13, 2023.

(h) Repetitive Reporting Requirement for All Airplanes

At the applicable compliance times specified in paragraphs
(h)(1) and (2) of this AD: Submit a report of all findings from each
work package performed as required by paragraph (g) of this AD, in
accordance with Appendix C of the applicable Boeing multi operator
message identified in paragraphs (g)(1) though (3) of this AD.
(1) For the initial inspections and measurements required by
paragraph (g) of this AD, submit the report at the applicable
compliance time specified in paragraph (h)(1)(i) or (ii) of this AD.
(i) For Model 747 airplanes operated in a passenger
configuration: Within 120 days after the effective date of this AD.
(ii) For Model 747 airplanes operated in an all-cargo
configuration: Within 150 days after the effective date of this AD.
(2) For each repetitive inspection and measurement required by
paragraph (g) of this AD, submit the report at intervals not to
exceed 30 days after completing all four work packages.

(i) Alternative Methods of Compliance (AMOCs)

(1) The Manager, AIR-520, Continued Operational Safety 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#b48d99f5faf999e7d1d5c0c0d8d199f5f7fb99f5f9fbf799e6d1c5c1d1c7c0c7f4d2d5d59ad3dbc2">[email&#160;protected]</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, AIR-
520, Continued Operational Safety 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) Related Information

For more information about this AD, contact Samuel Dorsey,
Aviation Safety Engineer, FAA, 2200 South 216th St., Des Moines, WA
98198; phone: 206-231-3415; email: <a href="/cdn-cgi/l/email-protection#144775796171783a7e3a707b6667716d547275753a737b62">[email&#160;protected]</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 Multi Operator Message MOM-MOM-23-0885-01B-R1, dated
November 13, 2023.
(ii) Boeing Multi Operator Message MOM-MOM-23-0899-01B-R1, dated
November 13, 2023.
(iii) Boeing Multi Operator Message MOM-MOM-23-0907-01B, dated
November 13, 2023.
(3) For Boeing material 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 material 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 material at the National Archives and
Records Administration (NARA). For information on the availability
of this material at NARA,

[[Page 83498]]

visit <a href="http://www.archives.gov/federal-register/cfr/ibr-locations">www.archives.gov/federal-register/cfr/ibr-locations</a>, or email
<a href="/cdn-cgi/l/email-protection#bfd9cd91d6d1cccfdadccbd6d0d1ffd1decdde91d8d0c9">[email&#160;protected]</a>.

Issued on November 20, 2023.
Caitlin Locke,
Director, Compliance & Airworthiness Division, Aircraft Certification
Service.
[FR Doc. 2023-26367 Filed 11-27-23; 4:15 pm]
BILLING CODE 4910-13-P

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