[Federal Register Volume 86, Number 178 (Friday, September 17, 2021)]
[Rules and Regulations]
[Pages 51788-51792]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 2021-20035]


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DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 39

[Docket No. FAA-2021-0263; Project Identifier AD-2020-01702-T; 
Amendment 39-21710; AD 2021-18-09]
RIN 2120-AA64


Airworthiness Directives; The Boeing Company Airplanes

AGENCY: Federal Aviation Administration (FAA), DOT.

ACTION: Final rule.

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SUMMARY: The FAA is adopting a new airworthiness directive (AD) for all 
The Boeing Company Model 777 airplanes. This AD was prompted by a 
report that an operator found solid rivets with missing heads at the 
left buttock line 25 on the sloping pressure deck web. This AD requires 
doing a detailed inspection of the left- and right-side sloping 
pressure deck at certain stations for any damaged solid rivets, and 
applicable on-condition actions. The FAA is issuing this AD to address 
the unsafe condition on these products.

DATES: This AD is effective October 22, 2021.
    The Director of the Federal Register approved the incorporation by 
reference of a certain publication listed in this AD as of October 22, 
2021.

ADDRESSES: 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; internet https://www.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 
https://www.regulations.gov by searching for and locating Docket No. 
FAA-2021-0263.

Examining the AD Docket

    You may examine the AD docket at https://www.regulations.gov by 
searching for and locating Docket No. FAA-2021-0263; or in person at 
Docket Operations between 9 a.m. and 5 p.m., Monday through Friday, 
except Federal holidays. The AD docket contains this final rule, any 
comments received, and other information. The address for Docket 
Operations is U.S. Department of Transportation, Docket Operations, M-
30, West Building Ground Floor, Room W12-140, 1200 New Jersey Avenue 
SE, Washington, DC 20590.

FOR FURTHER INFORMATION CONTACT: Luis Cortez, Aerospace Engineer, 
Airframe Section, FAA, Seattle ACO Branch, 2200 South 216th St., Des 
Moines, WA 98198; phone and fax: (206) 231-3958; email: Luis.A.Cortez-Muniz@faa.gov.

SUPPLEMENTARY INFORMATION:

Background

    The FAA issued a notice of proposed rulemaking (NPRM) to amend 14 
CFR part 39 by adding an AD that would apply to all The Boeing Company 
Model 777 airplanes. The NPRM published in the Federal Register on 
April 9, 2021 (86 FR 18479). The NPRM was

[[Page 51789]]

prompted by a report that an operator found solid rivets with missing 
heads at the left buttock line 25 on the sloping pressure deck web. In 
the NPRM, the FAA proposed to require doing a detailed inspection of 
the left- and right-side sloping pressure deck at certain stations for 
any damaged solid rivets, and applicable on-condition actions. The FAA 
is issuing this AD to address damaged or missing solid rivet heads on 
the sloping pressure deck web, which could result in loss of sloping 
pressure deck panels, causing decompression and pressure loss, and loss 
of the hydraulic systems in the area for wheel brakes (both normal and 
alternate) and steering, and potentially leading to runway departure 
and adversely affecting the structural integrity of the airplane.

Discussion of Final Airworthiness Directive

Comments

    The FAA received comments from four commenters, including Boeing, 
American Airlines (AA), FedEx, and United Airlines (UAL). The following 
presents the comments received on the NPRM and the FAA's response to 
each comment.

Request To Revise the On-Condition Actions Statement

    Boeing requested a revision to the on-condition actions statement 
in the third sentence of the ``Related Service Information Under 1 CFR 
part 51'' paragraph of the NPRM. Boeing stated that the repetitive 
detailed inspections cover ``two rows of fasteners common to the 
affected stiffener,'' instead of ``two rows of blind fasteners and 
solid rivets common to the affected stiffener.'' Boeing commented that 
the blind fastener repair option is allowed only under Condition 2 of 
Boeing Alert Requirements Bulletin 777-53A0093 RB, dated November 24, 
2020, which is limited to findings of a maximum of nine damaged rivets 
within the same stiffener. Boeing commented that the damage rivets must 
be within the same fastener row, and therefore, the compliance action 
does not allow for blind fasteners to be installed in both fastener 
rows of an affected stiffener. Boeing commented that the revised 
language improves clarity of the on-condition actions because it does 
not imply that blind fasteners can be installed in both fastener rows 
of an affected stiffener.
    The FAA agrees to revise the on-condition actions statement in the 
``Related Service Information Under 1 CFR part 51'' paragraph of this 
final rule for the reasons provided above; the FAA has revised this 
final rule accordingly.

Request To Revise Cost of Compliance Paragraph

    Boeing requested a revision to the on-condition work-hours for 
replacing a blind fastener. Boeing stated that the blind fastener 
replacement does not require internal access, and therefore, the 328 
work-hours can be reduced to 11 work-hours as noted in Boeing 
Information Notice 777-53A0093 IN 01, dated January 27, 2021.
    The FAA agrees to revise the on-condition work-hours for replacing 
a blind fastener for the reason provided above; this final rule has 
been revised accordingly.

Request To Clarify the Applicability

    AA asked if the rivet problems specified in the NPRM affect any 
airplanes in the AA livery, particularly N-numbers (nose numbers) so it 
can keep better track on preflights.
    For clarification, this AD does affect AA airplanes because its 
fleet includes Model 777-200 and -300ER airplanes. This AD applies to 
all Model 777-200, -200LR, -300, -300ER, and 777F airplanes, as 
specified in paragraph (c) of this AD. Since all Model 777 airplanes 
are affected, it is not necessary to identify airplanes by N-numbers. 
The FAA has not changed this AD in this regard.

Request To Revise the Compliance Time

    FedEx Express (FedEx) agreed with the intent of the proposed AD, 
but found the 16-month compliance time for the initial inspection does 
not align with its heavy maintenance visits and requested an extension. 
FedEx stated that its current heavy maintenance visits would be the 
suitable time to accomplish the actions in the proposed AD, and that 
accomplishing the initial inspection in the proposed AD may require 
performing special maintenance visits. FedEx commented that it 
currently has 26 Model 777F airplanes that have accumulated more than 
32,000 flight hours, and therefore, will be required to accomplish the 
initial inspection within the 16-month initial compliance time.
    FedEx also commented that since Boeing found the missing rivet 
heads from a retired Model 777-200 airplane, the current in-service 
Model 777 airplanes can operate with missing rivets without 
experiencing adverse structural complications since the issue was not 
discovered until after that airplane retired from service.
    The FAA disagrees with the commenter's request to extend the 
initial compliance time. The FAA cannot assume that Model 777 airplanes 
can operate with missing rivet heads without experiencing adverse 
structural complications. The FAA determined that the compliance time, 
as proposed, represents the maximum interval of time allowable for the 
affected airplanes to continue to safely operate before the initial and 
repetitive inspections and on-condition actions are done. If the 
inspection interval were based on maintenance schedules, which vary 
among operators, there would be no assurance that the airplane would be 
inspected and repaired during that maximum interval. In addition, in 
developing an appropriate compliance time, the FAA coordinated with the 
manufacturer to provide a compliance time with an acceptable level of 
safety. However, under the provisions of paragraph (i) of this AD, the 
FAA will consider requests for approval of an extension of the 
compliance time, if sufficient data are submitted to substantiate that 
the change would provide an acceptable level of safety. The FAA has not 
changed this AD in this regard.

Request To Clarify Required Service Information

    FedEx requested that the FAA revise note 1 to paragraph (g) in the 
proposed AD to clarify that the proposed AD requires accomplishment of 
the actions only specified in Boeing Alert Requirements Bulletin 777-
53A0093 RB, dated November 24, 2020. FedEx stated that note 1 does not 
clearly distinguish the required actions from the guidance service 
information for accomplishing the actions in the proposed AD.
    The FAA disagrees with the commenter's request to change the note. 
For clarification, paragraph (g) of this AD states the required actions 
for applicable airplanes, and only specifies to do all applicable 
actions identified in, and in accordance with, the Accomplishment 
Instructions of Boeing Alert Requirements Bulletin 777-53A0093 RB, 
dated November 24, 2020. The FAA clearly states that note 1 to 
paragraph (g) of this AD is guidance and Boeing Alert Service Bulletin 
777-53A0093, dated November 24, 2020, is only referred to in that note. 
The FAA has not changed this AD in this regard.

Request To Clarify Repair Instructions

    UAL indicated support for the NPRM, but requested clarification as 
to what to do if a Condition 4 is found in one stiffener and a 
Condition 3 is found in

[[Page 51790]]

another stiffener as referenced in Boeing Alert Service Bulletin 777-
53A0093, dated November 24, 2020. UAL stated that Condition 4 requires 
operators to contact Boeing and request repair instructions and to do 
the repair if any damaged rivet is found on both fastener rows within 
the same stiffener.
    In addition, UAL requested the following clarifications.
     When contacting Boeing, should operators provide all 
details of affected stiffeners regardless of the condition identified 
in Boeing Alert Service Bulletin 777-53A0093, dated November 24, 2020? 
UAL commented that Boeing Alert Service Bulletin 777-53A0093, dated 
November 24, 2020, appears to request details associated with a 
specific stiffener only.
     Where a Condition 4 discrepancy is present, is it 
acceptable to continue with the repair of an adjacent Condition 3 
stiffener discrepancy or is further manufacturer approval required?
    UAL stated that it assumes that the conservative approach would be 
for the operator to provide all details of affected stiffeners to the 
manufacturer and then the manufacturer will provide approval to repair 
both Conditions 3 and 4, as referenced in Boeing Alert Service Bulletin 
777-53A0093, dated November 24, 2020. UAL asserted that clarification 
will help operators determine which information is required by the 
manufacturer to make a repair assessment, and it will also provide 
clarification as to what to do in the event of a parallel process 
involving both Condition 3 and Condition 4 repair.
    The FAA provides the following clarification for the commenter. 
This AD requires operators to use Boeing Alert Requirements Bulletin 
777-53A0093 RB, dated November 24, 2020, to perform the actions 
required in this AD. Boeing Alert Service Bulletin 777-53A0093, dated 
November 24, 2020, is for guidance only. Boeing Alert Requirements 
Bulletin 777-53A0093 RB, dated November 24, 2020, does not specify any 
limitations on a Condition 3 repair based on any conditions found on 
another stiffener. When a Condition 3 is found, the FAA finds no issues 
with continuing with the Condition 3 repair of replacing all solid 
rivets even in the event a Condition 4 is found in an adjacent 
stiffener. Regarding the question on the details to provide to Boeing 
for a repair, as specified in Note 4. of 5.A., ``General Information,'' 
of Boeing Alert Requirements Bulletin 777-53A0093 RB, dated November 
24, 2020, operators can refer to Boeing Service Letter 777-SL-51-013, 
Damage Reporting and Repair Plan/Design Guidelines, which describes 
what information must be provided to Boeing before a structural repair 
can be provided. The structural repair must be approved by the FAA or 
the Boeing Company Organization Designation Authorization (ODA) as 
specified in paragraph (h)(2) of this AD. The FAA has not revised this 
AD in this regard.

Conclusion

    The FAA reviewed the relevant data, considered any comments 
received, and determined that air safety requires adopting this AD as 
proposed. 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 Alert Requirements Bulletin 777-53A0093 RB, 
dated November 24, 2020. This service information specifies procedures 
for doing a detailed inspection of the left- and right-side sloping 
pressure deck from station (STA) 1245 to STA 1287 for any damaged 
(i.e., missing solid rivet heads, cracking or deformation of the solid 
rivet, or gaps between the solid rivet head and the sloping pressure 
deck surface) solid rivets, and applicable on-condition actions. On-
condition actions include repeating the detailed inspection of the 
left-and right-side sloping pressure deck from STA 1245 to STA 1287 for 
any damaged solid rivet; repetitive detailed inspections of two rows of 
fasteners common to the affected stiffener for any damaged solid rivet 
or damaged blind fastener; replacing solid rivets or blind fasteners; 
and repair. 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 224 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
----------------------------------------------------------------------------------------------------------------
Detailed inspections.............  Up to 384 work-                  $0  Up to $32,640......  Up to $7,311,360.
                                    hours x $85 per
                                    hour = Up to
                                    $32,640.
----------------------------------------------------------------------------------------------------------------

    The FAA estimates the following costs to do any necessary 
replacements or inspections that would be required based on the results 
of the inspection. The agency has no way of determining the number of 
aircraft that might need these replacements or inspections:

                                               On-Condition Costs
----------------------------------------------------------------------------------------------------------------
                Action                        Labor cost               Parts cost            Cost per product
----------------------------------------------------------------------------------------------------------------
Replacement (solid fastener).........  338 work-hours x $85     Up to $3,200...........  Up to $31,930.
                                        per hour = $28,730.
Replacement (blind fastener).........  11 work-hour x $85 per   Up to $450.............  Up to $1,385.
                                        hour = $935.
Repetitive inspections of fastener     326 work-hours x $85     $0 per inspection cycle  $27,710 per inspection
 rows.                                  per hour = $27,710 per                            cycle.
                                        inspection cycle.
----------------------------------------------------------------------------------------------------------------


[[Page 51791]]

    The FAA has received no definitive data on which to base the cost 
estimates for the on-condition repairs specified in this AD.

Authority for This Rulemaking

    Title 49 of the United States Code specifies the FAA's authority to 
issue rules on aviation safety. Subtitle I, section 106, describes the 
authority of the FAA Administrator. Subtitle VII: Aviation Programs, 
describes in more detail the scope of the Agency's authority.
    The FAA is issuing this rulemaking under the authority described in 
Subtitle VII, Part A, Subpart III, Section 44701: General requirements. 
Under that section, Congress charges the FAA with promoting safe flight 
of civil aircraft in air commerce by prescribing regulations for 
practices, methods, and procedures the Administrator finds necessary 
for safety in air commerce. This regulation is within the scope of that 
authority because it addresses an unsafe condition that is likely to 
exist or develop on products identified in this rulemaking action.

Regulatory Findings

    This AD will not have federalism implications under Executive Order 
13132. This AD will not have a substantial direct effect on the States, 
on the relationship between the national government and the States, or 
on the distribution of power and responsibilities among the various 
levels of government.
    For the reasons discussed above, I certify that this AD:
    (1) Is not a ``significant regulatory action'' under Executive 
Order 12866,
    (2) Will not affect intrastate aviation in Alaska, and
    (3) Will not have a significant economic impact, positive or 
negative, on a substantial number of small entities under the criteria 
of the Regulatory Flexibility Act.

List of Subjects in 14 CFR Part 39

    Air transportation, Aircraft, Aviation safety, Incorporation by 
reference, Safety.

The Amendment

    Accordingly, under the authority delegated to me by the 
Administrator, the FAA amends 14 CFR part 39 as follows:

PART 39--AIRWORTHINESS DIRECTIVES

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:

2021-18-09 The Boeing Company: Amendment 39-21710; Docket No. FAA-
2021-0263; Project Identifier AD-2020-01702-T.

(a) Effective Date

    This airworthiness directive (AD) is effective October 22, 2021.

(b) Affected ADs

    None.

(c) Applicability

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

(d) Subject

    Air Transport Association (ATA) of America Code 53, Fuselage.

(e) Unsafe Condition

    This AD was prompted by a report that an operator found solid 
rivets with missing heads at the left buttock line 25 on the sloping 
pressure deck web. The FAA is issuing this AD to address damaged or 
missing solid rivet heads on the sloping pressure deck web, which 
could result in loss of sloping pressure deck panels, causing 
decompression and pressure loss, and loss of the hydraulic systems 
in the area for wheel brakes (both normal and alternate) and 
steering, and potentially leading to runway departure and adversely 
affecting the structural integrity of the airplane.

(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 777-53A0093 RB, dated November 24, 2020, 
do all applicable actions identified in, and in accordance with, the 
Accomplishment Instructions of Boeing Alert Requirements Bulletin 
777-53A0093 RB, dated November 24, 2020.

    Note 1 to paragraph (g): Guidance for accomplishing the actions 
required by this AD can be found in Boeing Alert Service Bulletin 
777-53A0093, dated November 24, 2020, which is referred to in Boeing 
Alert Requirements Bulletin 777-53A0093 RB, dated November 24, 2020.

(h) Exceptions to Service Information Specifications

    (1) Where Boeing Alert Requirements Bulletin 777-53A0093 RB, 
dated November 24, 2020, uses the phrase ``the original issue date 
of 777-53A0093 RB'' or ``the original issue date of Requirements 
Bulletin 777-53A0093 RB,'' this AD requires using ``the effective 
date of this AD,'' except where Alert Requirements Bulletin 777-
53A0093 RB, dated November 24, 2020, uses the phrase ``the original 
issue date of Requirements Bulletin 777-53A0093 RB'' in a note or 
flag note.
    (2) Where Boeing Alert Requirements Bulletin 777-53A0093 RB, 
dated November 24, 2020, specifies contacting Boeing for repair 
instructions: This AD requires doing the repair using a method 
approved 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 Related Information. Information may be emailed to: 9-ANM-Seattle-ACO-AMOC-Requests@faa.gov.
    (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) Related Information

    (1) For more information about this AD, contact Luis Cortez, 
Aerospace Engineer, Airframe Section, FAA, Seattle ACO Branch, 2200 
South 216th St., Des Moines, WA 98198; phone and fax: (206) 231-
3958; email: Luis.A.Cortez-Muniz@faa.gov.
    (2) Service information identified in this AD that is not 
incorporated by reference is available at the addresses specified in 
paragraphs (k)(3) and (4) of this AD.

(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 Alert Requirements Bulletin 777-53A0093 RB, dated 
November 24, 2020.
    (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; internet https://www.myboeingfleet.com.
    (4) You may view this service information at the FAA, 
Airworthiness Products Section, Operational Safety Branch, 2200 
South 216th

[[Page 51792]]

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 fr.inspection@nara.gov, or go to: https://www.archives.gov/federal-register/cfr/ibr-locations.html.

    Issued on August 25, 2021.
Gaetano A. Sciortino,
Deputy Director for Strategic Initiatives, Compliance & Airworthiness 
Division, Aircraft Certification Service.
[FR Doc. 2021-20035 Filed 9-16-21; 8:45 am]
BILLING CODE 4910-13-P


