AD 2025-03-10

This AD is effective March 21, 2025.

The Director of the Federal Register approved the incorporation by reference of a certain publication listed in this AD as of March 21, 2025.

AD Docket: You may examine the AD docket at regulations.gov under Docket No. FAA-2024-2408; 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 Boeing material 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.

• 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 at regulations.gov under Docket No. FAA-2024-2408.

Courtney Tuck, Aviation Safety Engineer, FAA, 2200 South 216th St., Des Moines, WA 98198; phone: 206-231-3986; email: Courtney.K.Tuck@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 certain The Boeing Company Model 747-400, 747-400F, 747-8F, and 747-8 series airplanes. The NPRM published in the Federal Register on November 12, 2024 (89 FR 88906). The NPRM was prompted by a report that, during potable water servicing, there were multiple engine indicating and crew alerting system messages. The cause was the separation of a fitting and steel water supply tube above an electronics equipment cooling air filter, behind the forward cargo compartment left sidewall. In the NPRM, the FAA proposed to require, depending on configuration, installing at certain locations: conduits on exposed potable water supply lines, envelope assemblies over all exposed potable water line fittings and exposed potable water supply lines, a slitted spray shield, a two-piece deflector shield around the ECS air inlet, and/or a shroud on exposed potable water supply lines. The FAA is issuing this AD to address water leaks into the main electronics center. This condition, if not addressed, could result in an adverse impact on the function of multiple electronics and line replaceable units (LRUs) in the equipment bay racks that are essential for safe flight, which can lead to the loss of continued safe flight and landing.

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

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.

The FAA reviewed Boeing Alert Requirements Bulletin 747-38A2146 RB, dated August 7, 2024. This material specifies procedures for, depending on configuration, installing: conduits on exposed potable water supply lines between station (STA) 580 and STA 650, between STA 575 and STA 650, or between STA 595 and STA 650, as applicable; envelope assemblies over all exposed potable water line fittings and exposed potable water supply lines between STA 650 and STA 660, between STA 640 and STA 660, between STA 570 and STA 580, between STA 570 and STA 580 and between STA 650 and STA 660, between STA 580 and STA 600 and between STA 650 and STA 660, or between STA 580 and STA 600, as applicable; a slitted spray shield; a two-piece deflector shield around the ECS air inlet STA 610; a spray shield; and/or a shroud on exposed potable water supply line between STA 550 and STA 680.

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 affects 178 airplanes of U.S. registry. The FAA estimates the following costs to comply with this AD:

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.

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: