AD 2021-14-10

This AD is effective August 19, 2021.

The Director of the Federal Register approved the incorporation by reference of a certain publication listed in this AD as of August 19, 2021.

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 562-797-1717; internet https://www.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 https://www.regulations.gov by searching for and locating Docket No. FAA-2021-0258.

Julie Linn, Aerospace Engineer, Cabin Safety and Environmental Systems Section, FAA, Seattle ACO Branch, 2200 South 216th St., Des Moines, WA 98198; phone and fax: 206-231-3584; email: Julie.Linn@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, 747-400D, and 747-400F series airplanes. The NPRM published in the Federal Register on April 13, 2021 (86 FR 19160). The NPRM was prompted by reports of burned BMS 8-39 urethane foam found in certain locations on the airplane; investigation revealed that the fire-retardant properties degrade with age. In the NPRM, the FAA proposed to require inspecting the insulation blankets in certain areas of the forward cargo compartment for exposed BMS 8-39 urethane foam, not encapsulated by a protective fire resistant barrier, and for seal integrity, and replacing the BMS 8-39 urethane foam and seal if necessary. The FAA is issuing this AD to address degraded BMS 8-39 urethane foam used in seals, which may fail to maintain sufficient halon concentrations in the cargo compartments to extinguish or contain fire or smoke, and may fail to prevent penetration of fire or smoke in areas of the airplane that are difficult to access for fire and smoke detection or suppression, which could result in loss of control of the airplane.

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

The FAA reviewed the relevant data, considered the comment received, and determined that air safety requires adopting this AD as proposed. 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 Special Attention Requirements Bulletin 747-25-3725 RB, dated October 27, 2020. This service information specifies procedures for doing a general visual inspection of the insulation blankets in the area between station (STA) 960 and STA 1000 on the left and right sides of the forward cargo compartment for exposed BMS 8-39 urethane foam, not encapsulated by a protective fire resistant barrier, and seal integrity, and replacing any BMS 8-39 urethane foam that is found exposed and any seal that does not have acceptable integrity for a smoke barrier. 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 the ADDRESSES section.

The FAA estimates that this AD affects 109 airplanes of U.S. registry. The FAA estimates the following costs to comply with this AD:

The FAA estimates the following costs to do any necessary on-condition actions that are required. The FAA has no way of determining the number of aircraft that might need these on-condition actions:

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: