
[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 [www.gpo.gov]
[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:
     Federal eRulemaking Portal: Go to 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.
    AD Docket: You may examine the AD docket at regulations.gov 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:
     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 myboeingfleet.com.
     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 
regulations.gov 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: [email protected].

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 regulations.gov, 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: [email protected]. 
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.
     For Model 747-8 and 747-8F series airplanes: Boeing Multi 
Operator Message MOM-MOM-23-0885-01B-R1, dated November 13, 2023.
     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.)
     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.

(c) Applicability

    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: [email protected].
    (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: [email protected].

(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 myboeingfleet.com.
    (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 www.archives.gov/federal-register/cfr/ibr-locations, or email 
[email protected].

    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


