AD 2021-13-02

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-2020-1030.

Courtney Kronenberger, Aerospace Engineer, Cabin Safety and Environmental Systems Section, FAA, Seattle ACO Branch, 2200 South 216th St., Des Moines, WA 98198; phone and fax: 206-231-3986; email: courtney.a.kronenberger@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 777-300ER series airplanes. The NPRM published in the Federal Register on December 29, 2020 (85 FR 85557). The NPRM was prompted by report indicating that a production design change to certain insulation blankets inadvertently opened up leakage paths for halon and smoke to escape from the aft cargo compartment in the event of a fire. In the NPRM, the FAA proposed to require installation of an insulation blanket assembly on top of existing insulation blankets in certain areas of the forward endwall in the aft cargo compartment. The FAA is issuing this AD to address increased leakage paths, which, in the event of a fire, could result in loss of fire suppressant in the cargo compartment, and could lead to an uncontained fire and subsequent loss of the airplane.

The FAA received comments from one commenter, Boeing, who supported the NPRM without change.

The FAA received additional comments from one commenter, United Airlines. The following presents the comments received on the NPRM and the FAA's response to each comment.

United Airlines stated that it agrees with the intent of the proposed AD. United Airlines also recommended that Boeing update the applicable IPC to show configuration control of the new part numbers that are installed during the accomplishment of the actions specified in the referenced service information. United Airlines noted that the update would provide proper configuration control and documentation support to maintain the new insulation blanket installation changes made prior to the release of the AD. United Airlines also asserted that the change could mitigate incorrect blanket installation.

The FAA acknowledges the commenter's recommendation and reasoning. However, the FAA does not control or require changes to the IPC. The FAA has not changed this AD in this regard.

The FAA reviewed the relevant data, considered any comments 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 777-25-0753 RB, dated July 31, 2020. This service information specifies procedures for installing an insulation blanket assembly on top of existing insulation blankets on the left and right side corner of the forward endwall in the aft cargo compartment. 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.

The FAA estimates that this AD affects 22 airplanes of U.S. registry. The FAA estimates the following costs to comply with this AD:

According to the manufacturer, some or all of the costs of this AD may be covered under warranty, thereby reducing the cost impact on affected operators. The FAA does not control warranty coverage for affected operators. As a result, the FAA has included all known costs in the cost estimate.

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: