AD 2023-25-12

This AD is effective February 7, 2024.

The Director of the Federal Register approved the incorporation by reference of a certain publication listed in this AD as of February 7, 2024.

AD Docket: You may examine the AD docket at regulations.gov under Docket No. FAA-2023-1711; 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, the mandatory continuing airworthiness information (MCAI), 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 incorporated by reference in this AD, contact EASA, Konrad-Adenauer-Ufer 3, 50668 Cologne, Germany; telephone +49 221 8999 000; email ADs@easa.europa.eu; website easa.europa.eu. You may find this material on the EASA website at ad.easa.europa.eu.

• You may view this material 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 in the AD docket at regulations.gov under Docket No. FAA-2023-1711.

Tim Dowling, Aviation Safety Engineer, FAA, 1600 Stewart Avenue, Suite 410, Westbury, NY 11590; telephone 206-231-3667; email timothy.p.dowling@faa.gov.

The FAA issued a notice of proposed rulemaking (NPRM) to amend 14 CFR part 39 by adding an AD that would apply to all Airbus SAS Model A318-112 airplanes; Model A319-115, -132, -133, -151N, -153N, and -171N airplanes; Model A320-211, -212, -214, -231, -232, -251N, -252N, -253N, -271N, -272N, and -273N airplanes; and Model A321-112 airplanes. The NPRM published in the Federal Register on August 17, 2023 (88 FR 55953). The NPRM was prompted by AD 2023-0014, dated January 18, 2023, issued by EASA, which is the Technical Agent for the Member States of the European Union (EASA AD 2023-0014) (also referred to as the MCAI). The MCAI states that computations conducted on the Model A320 family program showed that the fatigue life limit of the motoreductor, installed on the on-board entrance stairs and acting as one of the two (stair) immobilization systems, is not demonstrated for the complete airplane design service goal (DSG). Therefore, a motoreductor failure could remain undetected during the period between the demonstrated life limit of the motoreductor and the airplane DSG (and subsequent extended service goal). A failed motoreductor, if not corrected, could lead to an airstairs deployment in flight, possibly resulting in loss of control of the airplane.

In the NPRM, the FAA proposed to require repetitive replacement of the motoreductor for onboard entrance stairs, and limit the installation of affected parts under certain conditions, as specified in EASA AD 2023-0014. The FAA is issuing this AD to address the unsafe condition on these products.

You may examine the MCAI in the AD docket at regulations.gov under Docket No. FAA-2023-1711.

The FAA received comments from a commenter, American Airlines (AAL). The following presents the comments received on the NPRM and the FAA's response to each comment.

AAL requested revising paragraph (c) of the proposed AD to narrow the scope of affected airplanes to only those that have had certain modifications accomplished for installing airstairs on the affected Airbus SAS model airplanes (identified as Group 1 airplanes in EASA AD 2023-0014). AAL acknowledged that the FAA carried over EASA AD 2023-0014's applicability statement on all serial numbers of the affected Airbus SAS models. AAL also noted that the replacement action is only necessary if the airplane is equipped with the airstairs.

The FAA agrees that the replacement actions are only required for airplanes equipped with the affected airstairs (Group 1 airplanes). However, the FAA has determined it is necessary to retain the proposed applicability that is based on EASA's determination of the effectivity of EASA AD 2023-0014. Airplanes that have airstairs installed after the effective date would be subject to the requirements of this AD. Removing airplanes identified as Group 2 airplanes in EASA AD 2023-0014 (airplanes not equipped with the affected airstairs) would remove this AD from those airplanes' records and possibly increase the risk that the affected airstair part could be installed during a later modification of the Group 2 airplane into a Group 1 airplane without the operator's awareness that the requirements of this AD would then apply to that airplane. A Group 2 airplane with on-board entrance stairs becomes a Group 1 airplane. Operators can check the airplane's maintenance records to monitor the Group status and determine the applicable requirements for that airplane. The FAA has not changed this AD as a result of this comment.

This product has been approved by the aviation authority of another country and is approved for operation in the United States. Pursuant to the FAA's bilateral agreement with this State of Design Authority, it has notified the FAA of the unsafe condition described in the MCAI referenced above. The FAA reviewed the relevant data, considered the comment 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 this product. 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.

EASA AD 2023-0014 specifies procedures for repetitive replacement of the motoreductor for Airbus on-board entrance stairs, including a detailed inspection to determine the threshold for replacement. This material is reasonably available because the interested parties have access to it through their normal course of business or by the means identified in the ADDRESSES section.

The FAA estimates that this AD will affect 954 airplanes of U.S. registry. The FAA estimates the following costs to comply with this AD:

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.

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.

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

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

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