Airworthiness Directives; The Boeing Company Airplanes

[Federal Register Volume 88, Number 129 (Friday, July 7, 2023)]
[Rules and Regulations]
[Pages 43253-43256]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 2023-14331]


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DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 39

[Docket No. FAA-2023-0157; Project Identifier AD-2022-01309-T; 
Amendment 39-22466; AD 2023-12-08]
RIN 2120-AA64


Airworthiness Directives; The Boeing Company Airplanes

AGENCY: Federal Aviation Administration (FAA), DOT.

ACTION: Final rule.

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SUMMARY: The FAA is adopting a new airworthiness directive (AD) for 
certain The Boeing Company Model 747-8 series airplanes. This AD was 
prompted by a report of stress corrosion cracking in certain stringers 
and end stringer splice assemblies. This AD requires repetitive 
inspections of the stringers and end stringer splice assemblies for any 
crack, shim, or gap, and applicable on-condition actions. The FAA is 
issuing this AD to address the unsafe condition on these products.

DATES: This AD is effective August 11, 2023.
    The Director of the Federal Register approved the incorporation by 
reference of a certain publication listed in this AD as of August 11, 
2023.

ADDRESSES: 
    AD Docket: You may examine the AD docket at regulations.gov under 
Docket No. FAA-2023-0157; or in person at Docket Operations between 9 
a.m. and 5 p.m., Monday through Friday, except Federal holidays. The AD 
docket contains this final rule, any comments received, and other 
information. The address for Docket Operations is U.S. Department of 
Transportation, Docket Operations, M-30, West Building Ground Floor, 
Room W12-140, 1200 New Jersey Avenue SE, Washington, DC 20590.
    Material Incorporated by Reference:
    <bullet> For service information identified in this final rule, 
contact Boeing Commercial Airplanes, Attention: Contractual & Data 
Services (C&DS), 2600 Westminster Blvd., MC 110-SK57,

[[Page 43254]]

Seal Beach, CA 90740-5600; telephone 562-797-1717; website 
myboeingfleet.com.
    <bullet> You may view this service information at the FAA, 
Airworthiness Products Section, Operational Safety Branch, 2200 South 
216th St., Des Moines, WA. For information on the availability of this 
material at the FAA, call 206-231-3195. It is also available at 
regulations.gov under Docket No. FAA-2023-0157.

FOR FURTHER INFORMATION CONTACT: Stefanie N. Roesli, Aviation Safety 
Engineer, FAA, 2200 South 216th Street, Des Moines, WA 98198; phone: 
206-231-3964; email: [email protected].

SUPPLEMENTARY INFORMATION:

Background

    The FAA issued a notice of proposed rulemaking (NPRM) to amend 14 
CFR part 39 by adding an AD that would apply to certain The Boeing 
Company Model 747-8 series airplanes. The NPRM published in the Federal 
Register on February 15, 2023 (88 FR 9773). The NPRM was prompted by a 
report indicating cracks found on end stringers of two Model 747-8 
airplanes at station (STA) 2285, left and right sides, during foreign 
object debris (FOD) inspections in preparation for airplane 
modification. The cracks were not visually detectable until the 
stringer splice assemblies were removed. The root cause was found to be 
stress corrosion cracking caused by excessive and sustained internal 
tensile stresses that were due to no shim being installed or shimmed 
gaps exceeding engineering limits at production. In the NPRM, the FAA 
proposed to require repetitive inspections of the stringers and end 
stringer splice assemblies for any crack, shim, or gap, and applicable 
on-condition actions. The FAA is issuing this AD to prevent cracks in a 
stringer or end stringer splice assembly increasing in length and going 
undetected. This condition, if not addressed, could result in the 
inability of a structural element to sustain limit load and could 
adversely affect the structural integrity of the airplane.

Discussion of Final Airworthiness Directive

Comments

    The FAA received a comment from The Boeing Company who supported 
the NPRM without change.
    The FAA received an additional comment from an individual 
commenter. The following presents the comment received on the NPRM and 
the FAA's response to the comment.

Request for Root Cause of Stress Corrosion Cracks (SCCs)

    The individual commenter requested if Boeing provided heat 
treatment specification as a root cause of SCCs and the quality process 
for verification of SCC nucleation was within their shelf life. The 
individual indicated a larger production deficiency for an airplane 
that has been out of production, and stated that this unsafe condition 
should not be treated as widespread fatigue damage.
    During the root-cause investigation to determine the appropriate 
corrective actions, the FAA considered material changes and evaluated 
the manufacturing and assembly process. This evaluation would have 
included any necessary changes to treatment specifications and quality 
inspections. The FAA has not changed this AD.

Conclusion

    The FAA reviewed the relevant data, considered any comments 
received, and determined that air safety requires adopting this AD as 
proposed. Accordingly, the FAA is issuing this AD to address the unsafe 
condition on these products. Except for minor editorial changes, this 
AD is adopted as proposed in the NPRM. None of the changes will 
increase the economic burden on any operator.

Clarification of Terminating Action

    Boeing Alert Requirements Bulletin 747-53A2909 RB, dated September 
21, 2022, contains a terminating action flagnote (b) in Tables 1 
through 4 of the Accomplishment Instructions that specifies ``Doing the 
detailed and High Frequency Eddy Current (HFEC) inspections and finding 
no crack as a result of the inspection is terminating action to 
Requirements Bulletin 747-53A2909 RB for that affected end stringer 
splice assembly.'' However, the flagnote ``(b)'' is located with 
certain conditions in Tables 1 through 4 and appears to be 
contradictory in certain locations, e.g., ``Condition 8.2: No crack 
found as a result of option 2 inspections'' specifies to do repetitive 
inspections; however the option 2 inspections are the detailed and HFEC 
inspections, which the flagnote specifies is terminating action. The 
FAA has clarified the terminating action in paragraphs (g)(1) through 
(4) of this AD to confirm that no action is required for an end 
stringer splice assembly on which no cracking is found after the 
specified option 2 inspections are done.

Related Service Information Under 1 CFR Part 51

    The FAA reviewed Boeing Alert Requirements Bulletin 747-53A2909 RB, 
dated September 21, 2022. This service information specifies procedures 
for repetitive detailed inspections of the stringers and the end 
stringer splice assemblies at stringers S-17 to S-25 from STA 2285 to 
STA 2300 main entry door #5 cutout aft edge frame for any crack, any 
shim between a stringer and bear strap, and any gap within the 
fastener-joint-to-bear-strap joint, and applicable on-condition 
actions. On-condition actions include detailed inspections of the 
stringers and end stringers splice assemblies located between STA 2285 
and STA 2300 from stringers S-17L to S-25L/S-17R to S-25R, open hole 
high HFEC inspection of the fastener holes of the skin common to the 
end stringer splice fitting for cracks, and repair of cracked stringer/
end stringer splice fittings.
    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 2 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 Inspection (S-17L to S- 4 work-hours x $85 per               $0   $340 per            $680 per
 25L) and (S-17R to S-25R).       hour = $340 per                           inspection cycle.   inspection
                                  inspection cycle.                                             cycle.
----------------------------------------------------------------------------------------------------------------


[[Page 43255]]

    The FAA estimates the following costs to do any necessary on-
condition actions that would be required based on the results of the 
proposed inspection. The agency has no way of determining which, if 
any, of the affected airplanes might need these on-condition actions:

                                               On-Condition Costs
----------------------------------------------------------------------------------------------------------------
                                                                                                     Cost per
                   Action                                 Labor cost                Parts cost        product
----------------------------------------------------------------------------------------------------------------
Detailed Inspection and Open Hole HFEC       54 work-hours x $85 per hour =                   $0          $4,590
 Inspection per side.                         $4,590.
Repair of cracked stringer/end stringer      13 work-hours x $85 per hour =                  600           1,705
 splice fitting.                              $1,105.
----------------------------------------------------------------------------------------------------------------

    The FAA has included all known costs in its cost estimate. 
According to the manufacturer, however, some or all of the costs of 
this AD may be covered under warranty, thereby reducing the cost impact 
on affected operators.

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:

2023-12-08 The Boeing Company: Amendment 39-22466; Docket No. FAA-
2023-0157; Project Identifier AD-2022-01309-T.

(a) Effective Date

    This airworthiness directive (AD) is effective August 11, 2023.

(b) Affected ADs

    None.

(c) Applicability

    This AD applies to The Boeing Company Model 747-8 series 
airplanes, certificated in any category, as identified in Boeing 
Alert Requirements Bulletin 747-53A2909 RB, dated September 21, 
2022.

(d) Subject

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

 (e) Unsafe Condition

    This AD was prompted by a report of stress corrosion cracking in 
the stringers and end stringer splice assemblies located between 
station (STA) 2285 and STA 2300 from stringers S-17 to S-25 on the 
left and right sides of the airplane caused by excessive and 
sustained internal tensile stresses that were due to no shim being 
installed or shimmed gaps exceeding engineering limits at 
production. A crack in a stringer or end stringer splice assembly 
could grow in length and go undetected. The unsafe condition, if not 
addressed, could result in the inability of a structural element to 
sustain limit load and could adversely affect 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 747-53A2909 RB, dated September 21, 
2022, do all applicable actions identified in, and in accordance 
with, the Accomplishment Instructions of Boeing Alert Requirements 
Bulletin 747-53A2909 RB, dated September 21, 2022. For this AD, 
terminating action for certain end stringer springer splice 
assemblies are specified in paragraphs (g)(1) through (4) of this 
AD.
    Note 1 to paragraph (g): Guidance for accomplishing the actions 
required by this AD can be found in Boeing Alert Service Bulletin 
747-53A2909, dated September 21, 2022, which is referred to in 
Boeing Alert Requirements Bulletin 747-53A2909 RB, dated September 
21, 2022.
    (1) For any end stringer splice assembly on which no cracking is 
found after accomplishing CONDITION 3 (OPTION 2) (ACTION 1) and 
CONDITION 3 (OPTION 2) (ACTION 2) inspections specified in Table 1 
of the Accomplishment Instruction of Boeing Alert Requirements 
Bulletin 747-53A2909 RB, dated September 21, 2022, no further action 
is required by this AD for that end stringer splice assembly.
    (2) For any end stringer splice assembly on which no cracking is 
found after accomplishing CONDITION 6 (OPTION 2) (ACTION 1) and 
CONDITION 6 (OPTION 2) (ACTION 2) inspections specified in Table 2 
of the Accomplishment Instruction of Boeing Alert Requirements 
Bulletin 747-53A2909 RB, dated September 21, 2022, no further action 
is required by this AD for that end stringer splice assembly.
    (3) For any end stringer splice assembly on which no cracking is 
found after accomplishing CONDITION 8 (OPTION 2) (ACTION 1) and 
CONDITION 8 (OPTION 2) (ACTION 2) inspections specified in Table 3 
of the Accomplishment Instruction of Boeing Alert Requirements 
Bulletin 747-53A2909 RB, dated September 21, 2022, no further action 
is required by this AD for that end stringer splice assembly.
    (4) For any end stringer splice assembly on which no cracking is 
found after accomplishing CONDITION 10 (OPTION 2)

[[Page 43256]]

(ACTION 1) and CONDITION 10 (OPTION 2) (ACTION 2) inspections 
specified in Table 4 of the Accomplishment Instruction of Boeing 
Alert Requirements Bulletin 747-53A2909 RB, dated September 21, 
2022, no further action is required by this AD for that end stringer 
splice assembly.

 (h) Exceptions to Service Information Specifications

    (1) Where the Compliance Time column and certain notes of the 
tables in the ``Compliance'' paragraph of Boeing Alert Requirements 
Bulletin 747-53A2909 RB, dated September 21, 2022, use the phrase 
``the original issue date of Requirements Bulletin 747-53A2909 RB,'' 
this AD requires using ``the effective date of this AD.''
    (2) Where Boeing Alert Requirements Bulletin 747-53A2909 RB, 
dated September 21, 2022, 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, 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, 
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 Stefanie N. Roesli, 
Aviation Safety Engineer, FAA, 2200 South 216th Street, Des Moines, 
WA 98198; phone: 206-231-3964; 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 Alert Requirements Bulletin 747-53A2909 RB, dated 
September 21, 2022.
    (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 June 13, 2023.
Michael Linegang,
Acting Director, Compliance & Airworthiness Division, Aircraft 
Certification Service.
[FR Doc. 2023-14331 Filed 7-6-23; 8:45 am]
BILLING CODE 4910-13-P

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