2023-06075. 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 Boeing Model 737-8 and 737-9 airplanes, and certain Model 737-600, -700, -700C, -800, -900, and -900ER series airplanes. This AD was prompted by reports of damage to the auxiliary power unit (APU) fuel line shroud located aft of the aft cargo area; investigation revealed that the placement of the pressure switch wire clamp assembly and its fastener allowed interference of the fastener against the APU fuel line shroud. This AD requires inspecting the APU fuel line shroud for damage, inspecting the pressure switch wire clamp for correct bolt orientation and horizontal distance from the APU fuel line shroud, 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 1, 2023.

The Director of the Federal Register approved the incorporation by reference of certain publications listed in this AD as of May 1, 2023.

ADDRESSES:

AD Docket: You may examine the AD docket at regulations.gov under Docket No. FAA-2022-1068; 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 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 [phone]; internet 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 under Docket No. FAA-2022-1068.

FOR FURTHER INFORMATION CONTACT:

Chris Baker, Aerospace Engineer, Propulsion Section, FAA, Seattle ACO Branch, 2200 South 216th St., 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 Boeing Model 737-8 and 737-9 airplanes, and certain Model 737-600, -700, -700C, -800, -900, and -900ER series airplanes. The NPRM published in the Federal Register on October 5, 2022 (87 FR 60347). The NPRM was prompted by reports of damage to the auxiliary power unit (APU) fuel line shroud located aft of the aft cargo area; investigation revealed that the placement of the pressure switch wire clamp assembly and its fastener allowed interference of the fastener against the APU fuel line shroud. In the NPRM, the FAA proposed to require inspecting the APU fuel line shroud for damage, inspecting the pressure switch wire clamp for correct bolt orientation and horizontal distance from the APU fuel line shroud, and applicable on-condition actions. The FAA is issuing this AD to address interference of the fastener against the APU fuel line shroud, possibly resulting in a damaged APU fuel line shroud and consequent failure of the APU fuel hose, which could result in a flammable fluid leak in an ignition zone.

Discussion of Final Airworthiness Directive

Comments

The FAA received a comment from The Air Line Pilots Association, International (ALPA), who supported the NPRM without change.

The FAA received a comment from Aviation Partners Boeing (APB), who has reviewed the NPRM and determined that the incorporation of STC ST00830SE for installation of blended or split scimitar winglets on Boeing 737NG airplanes does not affect compliance with the mandated actions in the proposed rule. APB supported the NPRM without change.

The FAA received additional comments from Erick Leon, Delta Air Lines (DAL), Southwest Airlines (SWA), Boeing, and American Airlines (AAL). The following presents the comments received on the NPRM and the FAA's response to each comment.

Request To Update Service Information

Eric Leon requested that the procedure for installing the wire clamp should be updated to prevent the fuel line shroud from being damaged. The commenter noted that APU manufacturers should be required to make necessary corrections on the installation requirements for APU fuel line shroud. Lastly, the commenter stated that it would be important to understand what regulations are doing to ensure installation requirements meet minimum safety requirements set by the FAA.

The FAA does not agree with the requested change by the commenter. As discussed in the NPRM, incorrect installation of the fastener of the pressure switch wire clamp allowed interference of the fastener against the APU fuel line shroud. This installation activity occurred as part of airplane production, and is not an area intended to be covered by the APU manufacturer's design or installation instructions. To address this issue, the Boeing Alert Requirements Bulletins mandated by this AD require an inspection to determine the orientation of the fastener installed for the pressure switch wire clamp. If the fastener is not installed correctly, it must be reinstalled according to the procedures provided by the Boeing Alert Requirements Bulletins. Correct installation of the fastener will eliminate the potential of the fastener contacting the APU fuel line shroud and prevent occurrences of damage to the APU fuel line shroud. Furthermore, the correct installation specified in the Boeing Alert Requirements Bulletins complies with applicable regulations and therefore meets the minimum FAA safety requirements. The FAA has not changed this AD in response to this comment.

Request To Include Revisions of Boeing Alert Requirements Bulletins

DAL, AAL, and Boeing asked to revise the AD to require new revisions of service information that Boeing is currently drafting. Boeing noted that they are drafting revisions to Boeing Alert Requirements Bulletin 737-38A1072 RB, dated February 25, 2022, and Boeing Alert Requirements Bulletin 737-38A1073 RB, dated February 25, 2022, to address the condition of a missing clamp. As an alternative, AAL asked the FAA to consider allowing “later approved revisions” of the service information.

The FAA acknowledges the commenters' concerns regarding the procedures in the service information involving a potential missing clamp. In light of the critical nature of the identified unsafe condition, the FAA does not consider it appropriate to delay this final rule until new service information is available. Revisions of Boeing Alert Requirements Bulletins 737-38A1072 RB and 737-38A1073 RB have not been submitted to the FAA for review and approval. Therefore, the FAA is unable to mandate those revisions as requested. Furthermore, we disagree to add a provision to the AD to allow the use of “later approved revisions” of the Boeing Alert Requirements Bulletins. The FAA can only mandate a published document since the mandated document becomes part of the AD as it is incorporated by reference. Therefore, we are unable to mandate a “later revision” that does not exist at the time of AD publication. The FAA has not changed this AD in response to this comment.

Request To Provide Allowances for On-Wing Repairs of Damage to the APU Fuel Line Shroud

DAL requested to provide allowances for on-wing repairs of damage to the APU fuel line shroud. DAL noted that any crack or hole found on the APU fuel line shroud or any damage which exposes bare metal on the APU fuel line shroud exceeding the blend-out limits requires replacing the existing shroud with a new or repaired shroud. DAL explained that the action of removing and re-installing the shroud represents a significant maintenance burden, estimated at up to 300 labor hours as noted in the Costs of Compliance/On-Condition Costs of the NPRM. DAL noted that they are aware of on-wing repair actions for similar damage on other aircraft models, which would alleviate the need for shroud removal, potentially reducing repair labor hours to approximately 20 labor hours.

The FAA does not agree with the requested change by DAL. The FAA is unable to provide allowances for on-wing repairs of the damaged APU fuel line shroud since such repair procedures are not provided in the service information mandated by this AD. However, if an alternative procedure is available that would provide an acceptable level of safety, such a procedure can be requested for FAA approval through the provisions of paragraph (i) of this AD. The FAA has not changed this AD in response to this comment.

Request Regarding Parts Availability

DAL's review of parts availability from information on MyBoeingFleet Part Page shows zero stock of MPN 346A2201-26 APU Fuel Line Shroud as of October 5, 2022, with one part expected to be available by June 25, 2023. The subject MPN 346A2201-26 is applicable to approximately 100 DAL 737-900ER aircraft. DAL stated lack of availability of this part could severely hamper their ability to comply with this AD in the time period proposed.

According to DAL, Boeing has advised DAL that they have what they believe to be an adequate number of MPN 346A2201-26 shrouds available, however these are under allocation control by Boeing. This condition minimizes an operator's ability to effectively plan for proper contingencies should a shroud require replacement as the operator will have to delay repair actions while awaiting Boeing to release and ship the part to the operator potentially delaying aircraft return to service. DAL stated that if an AD will mandate this action, parts must be available to accomplish the requirements under paragraph (g) of the proposed AD.

The FAA agrees to provide clarification. When the FAA assesses unsafe conditions and establishes compliance times for ADs, the agency accounts for the practical aspects associated with compliance, including parts availability. As indicated by the commenter, the manufacturer considers that parts availability will be adequate. Similarly, the FAA has not been informed of a potential shortage of necessary parts. Therefore, the FAA considers that the compliance time of three years is adequate for operators to acquire the necessary parts and accomplish the actions required by this AD. The FAA has not changed this AD in response to this comment.

Request To Include an Inspection for Clamp Presence as First Action and in Figure 2 of Boeing Alert Service Bulletin

DAL requested to include an inspection for clamp presence as the first action rather than current ACTION 1, mandated per paragraph (g)(1) of the proposed AD under Boeing Alert Requirements Bulletin 737-38A1072 RB, dated February 25, 2022. If the clamp is not installed, DAL requests a requirement to install the clamp prior to any work being performed. DAL also stated that Figure 2, sheet 3 of 4 of Boeing Alert Requirements Bulletin 737-38A1072 RB, dated February 25, 2022, should have a provision to inspect for the missing clamp prior to any work being performed. DAL suggested an additional paragraph be added to inspect for the missing clamp. DAL stated that if the final rule continues to require accomplishment of the Boeing Alert Requirements Bulletin rather than the forthcoming revision, ACTION 1 to establish inspection within 3 inches of the clamp cannot be accomplished if clamp is not present. Therefore, an inspection for the presence of the clamp must be done first. Then, installation of the clamp and the inspection included in ACTION 1 can be performed.

The FAA does not agree with the requested changes by DAL. As stated previously, in light of the critical nature of the identified unsafe condition, the FAA does not consider it appropriate to delay this final rule until new service information is available. In addition, a pressure switch wire clamp should be present at the location specified in the service information mandated by the AD in order for an airplane to conform to the type design. We have not received any reports from the manufacturer regarding airplanes delivered with a missing pressure switch wire clamp. Also, we have not received any reports regarding the potential of the pressure switch wire clamp failing in service. Therefore, we consider that the instructions provided in the service information are adequate to address the unsafe condition. If an operator discovers an airplane with a missing pressure switch wire clamp during the accomplishment of the service information, we recommend that the operator inform the manufacturer of that condition. Operators may also request an Alternative Method of Compliance (AMOC) using the provisions in paragraph (i) of this AD if necessary. The FAA has not changed this AD in response to this comment.

Request To Clarify an Airplane Maintenance Manual (AMM) Reference

DAL requested to clarify the AMM reference in Boeing Alert Requirements Bulletin 737-38A1072 RB, dated February 25, 2022, Part 2 for APU Fuel line shroud removal/installation to indicate the MAIN APU fuel line shroud. DAL stated the AMM 28-25-05 has two shroud removal procedures—MAIN and AFT. In AMM 28-25-05/401, step 1.C notes that the APU shroud is divided into 2 parts with the main shroud being the one between the center tank and the pressure bulkhead, which is the subject of Boeing Alert Requirements Bulletin 737-38A1072 RB, dated February 25, 2022, and the NPRM.

The FAA agrees that the AMM reference should be clarified to reflect the intent of the AD, which is to replace the Main APU fuel line shroud only. However, the procedures in the Boeing Alert Service Bulletin (SB) that refer to AMM 28-25-05 are not required for compliance with this AD, and therefore those procedures are not provided in the Boeing Alert Requirements Bulletin (RB). As stated in Note 1 to paragraph (g)(1) and Note 2 to paragraph (g)(2) of this AD, the Boeing Alert Service Bulletins (SB) provide guidance for accomplishing the actions required by this AD. The FAA has not changed this AD in response to this comment.

Request for Additional Instructions in Boeing Alert Requirements Bulletin

DAL stated that Boeing Alert Requirements Bulletin 737-38A1072 RB, dated February 25, 2022, Part 3, step 1.a. includes verbiage to ensure the damage is smoothed out and should not exceed 2 inches in length. DAL suggested an additional paragraph be provided to instruct operators to replace the existing shroud should the smoothing process require more than 2 inches. For Part 3, step 1.a., DAL stated there is no guidance should the smoothing be longer than 2 inches.

Additionally, DAL stated that Boeing Alert Requirements Bulletin 737-38A1072 RB, dated February 25, 2022, Part 3, step 1.b. indicates to not remove more than 0.018 inches of metal from the wall thickness. For Part 3, step 1.b., DAL stated there is no guidance should more than 0.018 inches of metal be removed.

The FAA does not agree with the requested changes by DAL. Although additional clarification as suggested by the commenter may be beneficial to operators, the FAA considers that the specific steps in the Requirements Bulletin (RB) are adequate to address the unsafe condition. Part 3 of the Service Bulletin (SB) provides one acceptable method of compliance. Part 3 of the SB provides an option to repair damage to the existing APU fuel line shroud. If the blend surface exceeds 2 inches, or if more than 0.018 inch of metal is removed from the wall thickness, the conditions required by Part 3 cannot be met, and therefore this option should not be taken. In this case, the FAA recommends the operator to follow the option provided by Part 2, which is to replace the APU fuel line shroud with a new or repaired shroud. As we clarified previously, the procedures identified by the commenter are not part of the Requirements Bulletin, and therefore are not required by this AD. Those procedures are provided in the Service Bulletin as guidance for accomplishing the actions required by this AD. The FAA has not changed this AD in response to this comment.

Request To Use Serviceable Parts

SWA stated the “Action” column of Table 1 in Boeing Alert Requirements Bulletin 737-38A1072 RB, dated February 25, 2022, and Boeing Alert Requirements Bulletin 737-38A1073 RB, dated February 25, 2022, specifies “Replace existing APU fuel line shroud with new or repaired shroud.” For Condition 1, Condition 2 (Option 2), and Condition 3, SWA requested clarification regarding the use of an APU fuel line shroud which is not “new or repaired,” but is otherwise in serviceable condition. We infer SWA requested that the FAA allow an option to use serviceable parts.

The FAA agrees with the requested change by SWA. The service instructions should allow for serviceable parts, not just “new or repaired” shrouds. This AD allows the installation of a “serviceable” APU fuel line shroud. A “serviceable” APU fuel line shroud is defined as an APU fuel line shroud that has been maintained using methods acceptable to the FAA and identified by the FAA as airworthy. The FAA has added paragraphs (h)(3) and (4) to this AD to include this information.

Request To Clarify the Location of the APU Fuel Line Shroud Damage

Boeing requested to clarify the location of the APU fuel line shroud damage. Boeing proposed to revise paragraph (e) of the NPRM to change the statement from: “This AD was prompted by reports of damage to the auxiliary power unit (APU) fuel line shroud located in the aft cargo area” to: “This AD was prompted by reports of damage to the auxiliary power unit (APU) fuel line shroud located aft of the aft cargo area.” This will more precisely describe the location of the APU fuel line shroud damage that was found.

The FAA agrees with the requested change by Boeing because it better describes the location of the APU fuel line shroud. The FAA has changed the SUMMARY , Background, and paragraph (e) of this AD as requested.

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 Bulletins 737-38A1072 RB and 737-38A1073 RB, both dated February 25, 2022. This service information specifies procedures for a general visual inspection of the APU fuel line shroud in the area within 3 inches of the fastener of the pressure switch wire clamp for any damage (any crack or hole, any damage that exposes bare metal on the APU fuel line shroud, and any dent damage found that decreases the outside diameter of the shroud by more than 0.031 inch); a detailed inspection of the pressure switch wire clamp to determine if the fastener of the pressure switch wire clamp is installed with the bolt head on top and the nut on the bottom, and that there is a minimum 1.5 inches of horizontal separation between the fastener of the pressure switch wire clamp and the APU fuel line shroud, and applicable on-condition actions. On-condition actions include replacing the existing APU fuel line shroud with a new or repaired shroud; repairing any damage to the APU fuel line shroud; reinstalling the fastener of the pressure switch wire clamp with the bolt head on top and the nut on the bottom; and reinstalling the pressure switch wire clamp assembly to make sure there is 1.5 inches minimum of horizontal separation between the fastener of the pressure switch wire clamp and the APU fuel line shroud. These documents are distinct since they apply to different airplane minor models. 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 1,919 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
One-time Inspections	2 work-hours × $85 per hour = $170	$0	$170	$326,230

The FAA estimates the following costs to do any necessary repairs, replacements, or re-installations 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 repairs, replacements, or re-installations:

On-Condition Costs

Action	Labor cost	Parts cost	Cost per product
Repair	Up to 3 work-hours × $85 per hour = Up to $255	$0	Up to $255.
Replacement (includes re-installation)	Up to 300 work-hours × $85 per hour = Up to $25,500	Up to $8,158	Up to $33,658.

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

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:

2023-04-17 The Boeing Company: Amendment 39-22364; Docket No. FAA-2022-1068; Project Identifier AD-2022-00358-T.

(a) Effective Date

This airworthiness directive (AD) is effective May 1, 2023.

(b) Affected ADs

None.

(c) Applicability

This AD applies to The Boeing Company airplanes identified in paragraphs (c)(1) and (2) of this AD, certificated in any category.

(1) Model 737-600, -700, -700C, -800, -900, and -900ER series airplanes, as identified in Boeing Alert Requirements Bulletin 737-38A1072 RB, dated February 25, 2022.

(2) Model 737-8 and 737-9 airplanes, as identified in Boeing Alert Requirements Bulletin 737-38A1073 RB, dated February 25, 2022.

(d) Subject

Air Transport Association (ATA) of America Code 28, Fuel.

(e) Unsafe Condition

This AD was prompted by reports of damage to the auxiliary power unit (APU) fuel line shroud located aft of the aft cargo area; investigation revealed that the placement of the pressure switch wire clamp assembly and the fastener allowed interference of the fastener against the APU fuel line shroud. The FAA is issuing this AD to address interference of the fastener against the APU fuel line shroud, possibly resulting in a damaged APU fuel line shroud and consequent failure of the APU fuel hose, which could result in a flammable fluid leak in an ignition zone.

(f) Compliance

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

(g) Required Actions

(1) For the airplanes identified in paragraph (c)(1) of this AD, except as specified by paragraph (h) of this AD: At the applicable times specified in the “Compliance” paragraph of Boeing Alert Requirements Bulletin 737-38A1072 RB, dated February 25, 2022, do all applicable actions identified in, and in accordance with, the Accomplishment Instructions of Boeing Alert Requirements Bulletin 737-38A1072 RB, dated February 25, 2022.

Note 1 to paragraph (g)(1):

Guidance for accomplishing the actions required by this AD can be found in Boeing Alert Service Bulletin 737-38A1072, dated February 25, 2022, which is referred to in Boeing Alert Requirements Bulletin 737-38A1072 RB, dated February 25, 2022.

(2) For the airplanes identified in paragraph (c)(2) of this AD, except as specified by paragraph (h) of this AD: At the applicable times specified in the “Compliance” paragraph of Boeing Alert Requirements Bulletin 737-38A1073 RB, dated February 25, 2022, do all applicable actions identified in, and in accordance with, the Accomplishment Instructions of Boeing Alert Requirements Bulletin 737-38A1073 RB, dated February 25, 2022.

Note 2 to paragraph (g)(2):

Guidance for accomplishing the actions required by this AD can be found in Boeing Alert Service Bulletin 737-38A1073, dated February 25, 2022, which is referred to in Boeing Alert Requirements Bulletin 737-38A1073 RB, dated February 25, 2022.

(h) Exceptions to Service Information Specifications

(1) Where the Compliance Time columns of the tables in the “Compliance” paragraphs of Boeing Alert Requirements Bulletin 737-38A1072 RB, dated February 25, 2022, use the phrase “the original issue date of Requirements Bulletin 737-38A1072 RB,” this AD requires using “the effective date of this AD.”

(2) Where the Compliance Time columns of the tables in the “Compliance” paragraphs of Boeing Alert Requirements Bulletin 737-38A1073 RB, dated February 25, 2022, use the phrase “the original issue date of Requirements Bulletin 737-38A1073 RB,” this AD requires using “the effective date of this AD.”

(3) Where the Action column in Table 1 of Boeing Alert Requirements Bulletin 737-38A1072 RB, dated February 25, 2022, uses the phrase “Replace existing APU fuel line shroud with new or repaired shroud,” this AD allows the installation of a “serviceable” APU fuel line shroud. A “serviceable” APU fuel line shroud is defined as an APU fuel line shroud that has been maintained using methods acceptable to the FAA and identified by the FAA as airworthy.

(4) Where the Action column in Table 1 of Boeing Alert Requirements Bulletin 737-38A1073 RB, dated February 25, 2022, uses the phrase “Replace existing APU fuel line shroud with new or repaired shroud,” this AD allows the installation of a “serviceable” APU fuel line shroud. A “serviceable” APU fuel line shroud is defined as an APU fuel line shroud that has been maintained using methods acceptable to the FAA and identified by the FAA as airworthy.

(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 paragraph (j) 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, 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

For more information about this AD, contact Chris Baker, Aerospace Engineer, Propulsion Section, FAA, Seattle ACO Branch, 2200 South 216th St., Des Moines, WA 98198; phone: [phone]; email: [e-mail].

(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 737-38A1072 RB, dated February 25, 2022.

(ii) Boeing Alert Requirements Bulletin 737-38A1073 RB, dated February 25, 2022.

(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 [phone]; internet 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, [e-mail], or go to: www.archives.gov/​federal-register/​cfr/​ibr-locations.html.

Issued on February 22, 2023.

Christina Underwood,

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