2024-06995. Airworthiness Directives; The Boeing Company Airplanes

AGENCY:

Federal Aviation Administration (FAA), DOT.

ACTION:

Final rule.

SUMMARY:

The FAA is adopting a new airworthiness directive (AD) for certain The Boeing Company Model 757-200, -200CB, and -300 series airplanes. This AD was prompted by a report of a crack at fuselage station (STA) 1640 frame web common to the lower hinge intercostal tee clip center hole of the upper fastener row. This AD requires a maintenance records check for existing repairs at STA 1640, repetitive ultrasonic (UT) inspections for cracking of the frame web, and applicable on-condition actions. The FAA is issuing this AD to address the unsafe condition on these products.

DATES:

This AD is effective May 8, 2024.

The Director of the Federal Register approved the incorporation by reference of a certain publication listed in this AD as of May 8, 2024.

ADDRESSES:

AD Docket: You may examine the AD docket at regulations.gov under Docket No. FAA-2023-1046; 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:

• For material identified in this final rule, contact Boeing Commercial Airplanes, Attention: Contractual & Data Services (C&DS), 2600 Westminster Boulevard, MC 110-SK57, Seal Beach, CA 90740-5600; telephone [phone]; website: myboeingfleet.com.

• You may view this material that is incorporated by reference 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-2023-1046.

FOR FURTHER INFORMATION CONTACT:

Wayne Ha, Aviation Safety Engineer, Continued Operational Safety Branch, FAA, 2200 South 216th Street, Des Moines, WA 98198; phone: [phone]; email: [e-mail].

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 757-200, -200CB, and -300 series airplanes. The NPRM published in the Federal Register on June 1, 2023 (88 FR 35783). The NPRM was prompted by a report of a crack at fuselage STA 1640 frame web common to the lower hinge intercostal tee clip center hole of the upper fastener row. In the NPRM, the FAA proposed to require a maintenance records check for existing repairs at STA 1640, repetitive UT inspections for cracking of the frame web, and applicable on-condition actions. The FAA is issuing this AD to address possible undetected cracking in the STA 1640 frame web common to the lower hinge intercostal tee clip center hole of the upper fastener row. Such cracking, if not addressed, could result in the inability of a principal structural element to sustain limit loads which could adversely affect the structural integrity of the airplane.

Discussion of Final Airworthiness Directive

Comments

The FAA received comments from Air Line Pilots Association, International, who supported the NPRM without change.

The FAA received additional comments from seven commenters, including Aviation Partners Boeing (APB), Boeing, Delta Air Lines (DAL), European Air Transport GmbH (DHL), FedEx Express, United Airlines (UAL), and VT Mobile Aerospace Engineering, Inc. (VT MAE). The following presents the comments received on the NPRM and the FAA's response to each comment.

Request To Correct the Location of the Unsafe Condition

Boeing requested that the location of the cracking be corrected from “inboard and center holes” to “center hole” of the upper fastener row in the Summary and Background of the NPRM, and paragraph (e) of the proposed AD. Boeing said that cracking was found only in the center hole.

The FAA agrees. The correction has been made in the specified sections of this AD.

Request To Change Inspection Requirement for Certain Converted Airplanes

VT MAE proposed that no additional inspection be required other than the inspection specified in VT MAE 15-Pallet Maintenance Planning Data (MPD) Supplement 757SF-MPD-01 for airplanes converted per VT MAE Supplemental Type Certificate (STC) ST04242AT. VT MAE asserted that Boeing has performed analysis of the modified airplanes, including the new STA 1640 frame, which is inspected as part of the VT MAE MPD Supplement 757SF-MPD-01.

The FAA disagrees with the commenter's request because sufficient data was not submitted to substantiate that the inspections specified in VT MAE MPD Supplement 757SF-MPD-01 would provide an acceptable level of safety. Under the provisions of paragraph (i) of this AD, however, the FAA will consider requests for approval of alternative actions and compliance times 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 a Certain Exception

DAL requested that paragraph (h)(3) of the proposed AD be amended or revised to clarify whether aircraft configured with STC ST01518SE but without winglets require the specified reduction in applicable compliance times and repeat intervals. DAL stated that this approved configuration was not clearly addressed in the proposed AD.

The FAA agrees to clarify. Because a longer compliance time for the identified configuration (STC ST01518SE without winglets) has not been evaluated, all configurations with the STC ST01518SE modification must be included in the requirement. The FAA has revised paragraph (h)(3) of this AD to specify that airplanes modified in accordance APB STC ST01518SE, with or without blended or scimitar blended winglets installed, have the reduced compliance time. However, as specified in paragraph (i) of this AD, the FAA will consider requests for approval of alternative actions and compliance times if sufficient data are submitted to substantiate that the change would provide an acceptable level of safety.

Request To Clarify What Prompted the NPRM

Boeing requested that the Background section of the NPRM be revised to clarify the sequence of events and the associated service documents that led to detection of the cracking that prompted the NPRM. Boeing asserted that the NPRM indicated that the crack was found as a result of inspections required by AD 2020-20-10, Amendment 39-21266 (85 FR 63002, October 6, 2020) (AD 2020-20-10), but the crack was actually found as a result of inspections required by AD 2018-06-07, Amendment 39-19227 (83 FR 13398, March 29, 2018) (AD 2018-06-07).

The FAA agrees that the AD number reference in the Background section of the NPRM described by Boeing should have been AD 2018-06-07 (which was superseded by AD 2020-20-10). However, since that portion of the Background section does not reappear in the final rule, no change to the final rule is necessary.

Request To Extend Compliance Time

APB, DAL, and DHL proposed that APB Service Bulletin AP757-53-005 be incorporated into the final rule. APB, DAL, DHL, and UAL suggested that paragraph (h)(3) of the proposed AD be revised to extend the required time for compliance. APB explained that APB Service Bulletin AP757-53-005 is currently in approval review by an independent DER (Designated Engineering Representative) for submittal to the FAA, and this service information proposes less restrictive compliance times than specified by paragraphs (g) and (h)(3) of the proposed AD. DHL added that halving the compliance time for the initial inspection is more burdensome than halving the time for repetitive inspections, which can still be accomplished during base maintenance events. DAL and UAL added that the reduced initial inspection time would mean that the inspection could not occur during a regularly scheduled check, resulting in extended unscheduled ground time and increased costs for operators.

The FAA does not agree. Waiting for the review and approval of APB Service Bulletin AP757-53-005 would delay the rulemaking process. The urgency of the unsafe condition warrants issuing this AD as proposed because it adequately addresses the unsafe condition. Until APB completes its evaluation of airplanes with APB STC ST01518SE installed to determine an appropriate compliance time for the inspection, the conservative factor of 2 will apply to these airplanes. Under the provisions of paragraph (i) of this AD, however, the FAA will consider requests for approval of alternative compliance times 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 for Clarification on Credit for Certain Airplanes

UAL requested clarification on the NPRM as it does not give operators credit for airplanes on which the required inspection in Boeing Alert Requirements Bulletin 757-53A0121 RB, dated September 28, 2022, was already accomplished prior to release of the pending AD. UAL said they intend to start inspection as soon as possible, and not having any allowance for credit prior to AD release may drive some of UAL's Model 757 fleet into another round of the required inspection sooner than the required repetitive inspection time limit.

The FAA provides the following clarification. Paragraph (f) of this AD states that operators must comply with the requirements of the AD unless those actions have already been done, which negates the need to add the requested credit. Any repetitive actions must be done within the compliance times required by this AD. This AD has not been changed regarding this request.

Request To Exclude Certain Airplanes From AD Requirements

VT MAE requested that no inspection be required for aircraft converted per ST03952AT that have a long inner chord strap at the STA 1640 fuselage frame. VT MAE and FedEx Express requested that no inspection be required for aircraft converted per VT MAE STC ST03562AT that have a long inner chord strap at the STA 1640 fuselage frame. The commenters asserted that the modified STA 1640 frame is identical to that of Boeing 757-200 special freighter airplanes, which are not included in Boeing Alert Requirements Bulletin 757-53A0121 RB, dated September 28, 2022. The commenters claimed that Boeing and the FAA stated that these special freighter-configured airplanes were not subject to cracking at the lower hinge intercostal tee clip. The commenters stated that the stresses in the inner chord are higher, and AD 2020-20-10 and Boeing Alert Service Bulletin 757-53A0108, Revision 1, dated July 17, 2019, would be able to detect the web cracks sooner.

The FAA agrees with the proposed change. For aircraft converted per VT MAE STC ST03562AT and ST03952AT that have a long inner chord strap at the STA 1640 fuselage frame, the modified STA 1640 frame is identical to that of Boeing 757-200 special freighter airplanes. Paragraph (h)(4) of this AD has been added to provide an exception stating that the actions of paragraph (g) of this AD are not required for Group 1 airplanes that have been converted from passenger to freighter configuration using VT MAE STC ST03562AT or ST03952AT that have a long inner chord strap at the STA 1640 fuselage frame.

Request for Alternative Required Actions for Certain Airplanes

VT MAE and FedEx Express requested the use of Group 4 inspections/methods/compliance times, given in Boeing Alert Requirements Bulletin 757-53A0121 RB, dated September 28, 2022, for the airplane having registration number N935FD, which was converted per VT MAE STC ST03562AT. The commenters noted that this airplane has a short inner chord strap at the STA 1640 fuselage frame, and that the modified STA 1640 frame is identical to the STA 1640 frame found on Boeing 757-200 special freighter airplanes, which are identified as Group 4 in Boeing Alert Requirements Bulletin 757-53A0121 RB, dated September 28, 2022.

The FAA agrees that the modified STA 1640 frame is identical to the STA 1640 frame found on Boeing 757-200 special freighter airplanes, identified as Group 4 in Boeing Alert Requirements Bulletin 757-53A0121 RB, dated September 28, 2022. The FAA has added paragraph (h)(5) of this AD to specify that airplanes modified in this manner should accomplish the actions for Group 4 airplanes at the applicable times for Group 4 airplanes, as specified in Boeing Alert Requirements Bulletin 757-53A0121 RB, dated September 28, 2022.

Limited ODA Approvals

APB stated that Boeing does not have a delegation to approve repairs in areas affected by the scimitar blended winglet configuration of STC ST01518SE. APB also commented that approval by The Boeing Company Organization Designation Authorization (ODA), as specified in paragraph (i)(3) of the proposed AD, may not be given for an alternative method of compliance (AMOC) for repairs in those areas, but such approval must be obtained as specified in paragraph (i)(1) of this AD.

The FAA acknowledges and concurs with APB's assertions. However, no change to the AD is necessary. Paragraph (h)(2) of this AD states that AMOC approval be obtained using a method approved in accordance with the procedures specified in “paragraph (i)” of this AD, and does not limit approvals to the provisions of paragraph (i)(1) or (3) of this AD. Therefore, AMOC approval in accordance with paragraph (i)(1) or (3) of this AD would be provided based on whether the actions needing an AMOC apply to the APB design or the Boeing design.

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, 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 757-53A0121 RB, dated September 28, 2022. This service information specifies procedures for a maintenance records check of the left- and right-side STA 1640 frame web between S-9 and S-20 for existing repairs; repetitive UT inspections of the frame web for any cracks; and applicable on-condition actions. On-condition actions include 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 section.

Costs of Compliance

The FAA estimates that this AD affects 309 airplanes of U.S. registry. The FAA estimates the following costs to comply with this AD:

Estimated Costs

Action	Labor cost	Parts cost	Cost per product	Cost on U.S. operators
Maintenance records check	1 work-hour × $85 per hour = $85	$0	$85	$26,265.
UT inspection	39 work-hours × $85 per hour = $3,315 per inspection cycle	$0	$3,315 per inspection cycle	$1,024,335 per inspection cycle.

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

1. The authority citation for part 39 continues to read as follows:

Authority: 49 U.S.C. 106(g), 40113, 44701.

§ 39.13

[Amended]

2. The FAA amends § 39.13 by adding the following new airworthiness directive:

2024-05-09 The Boeing Company: Amendment 39-22700; Docket No. FAA-2023-1046; Project Identifier AD-2023-00253-T.

(a) Effective Date

This airworthiness directive (AD) is effective May 8, 2024.

(b) Affected ADs

None.

(c) Applicability

This AD applies to The Boeing Company Model 757-200, -200CB, and -300 series airplanes, certificated in any category, as identified in Boeing Alert Requirements Bulletin 757-53A0121 RB, dated September 28, 2022.

(d) Subject

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

(e) Unsafe Condition

This AD was prompted by a report of a crack at fuselage station (STA) 1640 frame web common to the lower hinge intercostal tee clip center hole of the upper fastener row. This condition, if not addressed, could result in the inability of a principal structural element to sustain limit loads, which 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 757-53A0121 RB, dated September 28, 2022, do all applicable actions identified in, and in accordance with, the Accomplishment Instructions of Boeing Alert Requirements Bulletin 757-53A0121 RB, dated September 28, 2022.

Note 1 to paragraph (g): Guidance for accomplishing the actions required by this AD can be found in Boeing Alert Service Bulletin 757-53A0121, dated September 28, 2022, which is referred to in Boeing Alert Requirements Bulletin 757-53A0121 RB, dated September 28, 2022.

(h) Exceptions to Service Information Specifications

(1) Where the Compliance Time columns of the tables in the “Compliance” paragraph of Boeing Alert Requirements Bulletin 757-53A0121 RB, dated September 28, 2022, use the phrase “the original issue date of Requirements Bulletin 757-53A0121 RB,” this AD requires replacing those words with “the effective date of this AD.”

(2) Where Boeing Alert Requirements Bulletin 757-53A0121 RB, dated September 28, 2022, specifies contacting Boeing for repair instructions or for alternative inspections: This AD requires doing the repair, or doing the alternative inspections and applicable on-condition actions using a method approved in accordance with the procedures specified in paragraph (i) of this AD.

(3) For airplanes modified in accordance with Aviation Partners Boeing (APB) Supplemental Type Certificate (STC) ST01518SE, with or without blended or scimitar blended winglets installed: This AD requires dividing the applicable compliance times and repeat intervals specified in the “Compliance” paragraph of Boeing Alert Requirements Bulletin 757-53A0121 RB, dated September 28, 2022, by a factor of two.

(4) For Group 1 airplanes identified in Boeing Alert Requirements Bulletin 757-53A0121 RB, dated September 28, 2022, that have been converted from passenger to freighter configuration using VT MAE STC ST03562AT or ST03952AT and that have a long inner chord strap part number 146N8711-65 at the STA 1640 fuselage frame: The actions specified in paragraph (g) of this AD are not required.

(5) For Group 3 airplanes identified in Boeing Alert Requirements Bulletin 757-53A0121 RB, dated September 28, 2022, that have been converted from passenger to freighter configuration using VT MAE STC ST03562AT: Do all applicable actions for Group 4, as identified in, and in accordance with, Boeing Alert Requirements Bulletin 757-53A0121 RB, dated September 28, 2022, at the applicable times for Group 4 as specified in the “Compliance” paragraph of Boeing Alert Requirements Bulletin 757-53A0121 RB, dated September 28, 2022.

(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)(1) of this AD. Information may be emailed to: [e-mail].

(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

(1) For more information about this AD, contact Wayne Ha, Aviation Safety Engineer, Continued Operational Safety Branch, FAA, 2200 South 216th Street, Des Moines, WA 98198; phone: [phone]; email: [e-mail].

(2) Service information identified in this AD that is not incorporated by reference is available at the address specified in paragraph (k)(3) 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 757-53A0121 RB, dated September 28, 2022.

(ii) [Reserved]

(3) For material identified in this AD, contact Boeing Commercial Airplanes, Attention: Contractual & Data Services (C&DS), 2600 Westminster Boulevard, MC 110-SK57, Seal Beach, CA 90740-5600; telephone [phone]; website: myboeingfleet.com.

(4) You may view this material that is incorporated by reference at the FAA, Airworthiness Products Section, Operational Safety Branch, 2200 South 216th Street, 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, visit www.archives.gov/​federal-register/​cfr/​ibr-locations or [e-mail].

Issued on March 4, 2024.

Victor Wicklund,

Deputy Director, Compliance & Airworthiness Division, Aircraft Certification Service.