[Federal Register Volume 88, Number 66 (Thursday, April 6, 2023)]
[Proposed Rules]
[Pages 20433-20436]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 2023-07011]


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DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 39

[Docket No. FAA-2023-0436; Project Identifier AD-2022-00395-T]
RIN 2120-AA64


Airworthiness Directives; The Boeing Company Airplanes

AGENCY: Federal Aviation Administration (FAA), DOT.

ACTION: Notice of proposed rulemaking (NPRM).

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SUMMARY: The FAA proposes to adopt a new airworthiness directive (AD) 
for all The Boeing Company Model 777-200, 777-200LR, 777-300, 777-
300ER, and 777F series airplanes. This proposed AD was prompted by a 
report of a ``FLAPS DRIVE'' caution message in flight due to the torque 
trip indicator of the No. 2 trailing edge (TE) flap transmission 
assembly being in the set position, which resulted in an air turn-back. 
This proposed AD would require an inspection or records review to 
determine the serial numbers of the TE flap transmission and gearbox 
assemblies, and applicable on-condition corrective actions. This 
proposed AD would also limit the installation of affected parts. The 
FAA is proposing this AD to address the unsafe condition on these 
products.

DATES: The FAA must receive comments on this proposed AD by May 22, 
2023.

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 under 
Docket No. FAA-2023-0436; 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 NPRM, any comments received, and other 
information. The street address for Docket Operations is listed above.
    Material Incorporated by Reference:
     For service information identified in this NPRM, 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 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 
regulations.gov by searching for and locating Docket No. FAA-2023-0436.

[[Page 20434]]


FOR FURTHER INFORMATION CONTACT: Douglas Tsuji, Senior Aerospace 
Engineer, Systems and Equipment Section, FAA, Seattle ACO Branch, 2200 
South 216th St., Des Moines, WA 98198; phone: 206-231-3548; email: 
[email protected].

SUPPLEMENTARY INFORMATION:

Comments Invited

    The FAA invites you to send any written relevant data, views, or 
arguments about this proposal. Send your comments to an address listed 
under ADDRESSES. Include ``Docket No. FAA-2023-0436; Project Identifier 
AD-2022-00395-T'' at the beginning of your comments. The most helpful 
comments reference a specific portion of the proposal, 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 proposal because of those comments.
    Except for Confidential Business Information (CBI) as described in 
the following paragraph, and other 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 NPRM.

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 NPRM 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 NPRM, 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 NPRM. Submissions containing CBI should be sent to 
Douglas Tsuji, Senior Aerospace Engineer, Systems and Equipment 
Section, FAA, Seattle ACO Branch, 2200 South 216th St., Des Moines, WA 
98198; phone: 206-231-3548; 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 FAA has received a report of a ``FLAPS DRIVE'' caution message 
in flight, which resulted in an air turn-back. Subsequent investigation 
found that the torque trip indicator of the No. 2 trailing edge (TE) 
flap transmission assembly was in the set position, which had caused 
the ``FLAPS DRIVE'' caution message. The TE flap transmission assembly 
was removed from the airplane and sent for a teardown inspection to 
find the cause of the problem. The teardown inspection revealed a 
broken no-back brake ratchet pawl; the broken piece had lodged itself 
between the housing and a drive gear, which had resulted in a TE flap 
transmission assembly lock-up condition. A subsequent Boeing analysis 
of the broken pawl found that the spring guide pin bore did not meet 
design requirements. The depth of the pawl bore was more than the 
specified requirement, and its inner diameter was insufficient. 
Further, the drawing requirement for the pawl bore inner diameter 
resulted in an undersized spring guide pin bore, which caused an 
excessive interference fit between the bore and spring guide, which in 
turn caused the ratchet pawl assembly to break.
    From in-service reports, there have been three known incidents of 
Model 777 TE flap transmission no-back brake ratchet pawls cracking in 
service from the same supplier since 2018. The same ratchet pawl part 
number is used on all eight TE flap transmissions. Historically, these 
pawls have been fabricated by three different sub-tier suppliers. The 
three broken pawls were manufactured by the same sub-tier supplier, 
which is no longer in business. The root cause of the unsafe condition 
has been determined to be the undersized bores in the suspect pawls 
causing an interference fit with the mating spring guide pin resulting 
in increased hoop stresses in the pawl. A review of two inspection 
reports revealed that the sub-tier supplier had misread the bore 
requirements.
    A broken ratchet pawl assembly, in combination with an upstream 
torque tube disconnect, can cause failure of the no-back brake to hold 
flap surfaces in a commanded position--a condition referred to as flap 
``blowback.'' In addition, a broken ratchet pawl assembly can allow 
debris in the transmission assembly, which can prevent the pawl from 
engaging the ratchet plate or cause other damage to the transmission 
assembly. Both conditions can cause failure of the no-back brake, in 
combination with an upstream torque tube disconnect, which could lead 
to uncommanded retraction of the TE flap resulting in asymmetric loss 
of lift that can affect continued safe flight and landing.

FAA's Determination

    The FAA is issuing this NPRM after determining that the unsafe 
condition described previously is likely to exist or develop on other 
products of the same type design.

Related Service Information Under 1 CFR Part 51

    The FAA reviewed Boeing Alert Requirements Bulletin 777-27A0123 RB, 
Revision 1, dated January 16, 2023. This service information specifies 
procedures for an inspection or records review for affected serial 
numbers of the TE flap transmission and gearbox assemblies at positions 
1 through 8. For affected serial numbers, the service information 
specifies procedures for either (1) removing the TE flap transmission 
assembly and installing a new or serviceable assembly, or (2) removing 
the TE flap transmission and ratchet pawl assemblies, inspecting the 
ratchet pawl assembly for damage and missing material, and, depending 
on the findings, either installing a new ratchet pawl assembly and a 
changed TE flap transmission assembly or replacing the ratchet pawl 
assembly and TE flap transmission assembly with new or serviceable 
parts. 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.

Proposed AD Requirements in This NPRM

    This proposed AD would require accomplishing the actions specified 
in the service information already described. For information on the 
procedures and compliance times, see this service information at 
regulations.gov by searching for and locating Docket No. FAA-2023-0436.

Costs of Compliance

    The FAA estimates that this AD, if adopted as proposed, would 
affect 267 airplanes of U.S. registry. The FAA estimates the following 
costs to comply with this proposed AD:

[[Page 20435]]



                                                 Estimated Costs
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                                                                                    Cost per       Cost on U.S.
               Action                        Labor cost           Parts cost        product         operators
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Inspection or records review........  1 work-hour x $85 per                $0              $85          $22,695
                                       hour = $85.
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    The FAA estimates the following costs to do any necessary 
replacement(s) that would be required based on the results of the 
inspection or records review. The FAA has no way of determining the 
number of aircraft that might need these replacements:

                                    Estimated Costs for On-Condition Actions
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                                                                                                     Cost per
                 Action                          Labor cost                  Parts cost              product
----------------------------------------------------------------------------------------------------------------
Replacement............................  6 work-hours x $85 per      $5,090 per part...........          $5,600
                                          hour = $510.
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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 determined that this proposed AD would not have federalism 
implications under Executive Order 13132. This proposed AD would 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 this proposed 
regulation:
    (1) Is not a ``significant regulatory action'' under Executive 
Order 12866,
    (2) Would not affect intrastate aviation in Alaska, and
    (3) Would 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 Proposed Amendment

    Accordingly, under the authority delegated to me by the 
Administrator, the FAA proposes to amend 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:

The Boeing Company: Docket No. FAA-2023-0436; Project Identifier AD-
2022-00395-T.

(a) Comments Due Date

    The FAA must receive comments on this airworthiness directive 
(AD) by May 22, 2023.

(b) Affected ADs

    None.

(c) Applicability

    This AD applies to all The Boeing Company Model 777-200, 777-
200LR, 777-300, 777-300ER, and 777F series airplanes, certificated 
in any category.

(d) Subject

    Air Transport Association (ATA) of America Code 27, Flight 
controls.

(e) Unsafe Condition

    This AD was prompted by a report of a ``FLAPS DRIVE'' caution 
message in flight due to the torque trip indicator of the No. 2 
trailing edge (TE) flap transmission assembly being in the set 
position, which resulted in an air turn-back. The FAA is issuing 
this AD to address a broken ratchet pawl assembly in combination 
with an upstream torque tube disconnect, which can cause failure of 
the no-back brake to hold flap surfaces in a commanded position, and 
possible debris in the transmission assembly, which can prevent the 
pawl from engaging the ratchet plate or cause other damage to the 
transmission assembly. The unsafe condition, if not addressed, could 
result in asymmetric loss of the lift that can prevent continued 
safe flight and landing.

(f) Compliance

    Comply with this AD within the compliance times specified, 
unless already done.

(g) Required Actions

    Except as specified by paragraph (h) of this AD: At the 
applicable times specified in the ``Compliance'' paragraph of Boeing 
Alert Requirements Bulletin 777-27A0123 RB, Revision 1, dated 
January 16, 2023, do all applicable actions identified in, and in 
accordance with, the Accomplishment Instructions of Boeing Alert 
Requirements Bulletin 777-27A0123 RB, Revision 1, dated January 16, 
2023.
    Note 1 to paragraph (g): Guidance for accomplishing the actions 
required by this AD can be found in Boeing Alert Service Bulletin 
777-27A0123, Revision 1, dated January 16, 2023, which is referred 
to in Boeing Alert Requirements Bulletin 777-27A0123 RB, Revision 1, 
dated January 16, 2023.

(h) Exception to Service Information Specifications

    Where the Compliance Time columns of the tables in the 
``Compliance'' paragraph of Boeing Alert Requirements Bulletin 777-
27A0123 RB, Revision 1, dated January 16, 2023, use the phrase ``the 
original issue date of Requirements Bulletin 777-27A0123 RB,'' this 
AD requires using ``the effective date of this AD.''

(i) Credit for Previous Actions

    This paragraph provides credit for the actions specified in 
paragraph (g) of this AD, if those actions were performed before the 
effective date of this AD using Boeing Alert Requirements Bulletin 
777-27A0123 RB, dated October 11, 2021.

[[Page 20436]]

(j) Parts Installation Limitation

    As of the effective date of this AD, no person may install, on 
any airplane, an affected TE flap transmission or gearbox assembly, 
as identified in Appendix J of Boeing Alert Requirements Bulletin 
777-27A0123 RB, Revision 1, dated January 16, 2023, unless the 
assembly has been inspected and all applicable corrective actions 
have been performed in accordance with Boeing Alert Requirements 
Bulletin 777-27A0123 RB, Revision 1, dated January 16, 2023.

(k) 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 (l) 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, 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.

(l) Related Information

    For more information about this AD, contact Douglas Tsuji, 
Senior Aerospace Engineer, Systems and Equipment Section, FAA, 
Seattle ACO Branch, 2200 South 216th St., Des Moines, WA 98198; 
phone: 206-231-3548; email: [email protected].

(m) 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 Alert Requirements Bulletin 777-27A0123 RB, Revision 
1, dated January 16, 2023.
    (ii) [Reserved]
    (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 myboeingfleet.com.
    (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, [email protected], or go to: www.archives.gov/federal-register/cfr/ibr-locations.html.

    Issued on March 9, 2023.
Christina Underwood,
Acting Director, Compliance & Airworthiness Division, Aircraft 
Certification Service.
[FR Doc. 2023-07011 Filed 4-5-23; 8:45 am]
BILLING CODE 4910-13-P


