AD 2017-04-13

This AD is effective April 3, 2017.

The Director of the Federal Register approved the incorporation by reference of a certain publication listed in this AD as of April 3, 2017.

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; telephone 562-797-1717; Internet https://www.myboeingfleet.com. You may view this referenced service information at the FAA, Transport Airplane Directorate, 1601 Lind Avenue SW., Renton, WA. For information on the availability of this material at the FAA, call 425-227-1221. It is also available on the Internet at http://www.regulations.gov by searching for and locating Docket No. FAA-2016-9053.

Tung Tran, Aerospace Engineer, Propulsion Branch, ANM-140S, FAA, Seattle Aircraft Certification Office (ACO), 1601 Lind Avenue SW., Renton, WA 98057-3356; phone: 425-917-6505; fax: 425-917-6590; email: tung.tran@faa.gov.

We issued a notice of proposed rulemaking (NPRM) to amend 14 CFR part 39 by adding an AD that would apply to all The Boeing Company Model 747-8 and 747-8F series airplanes. The NPRM published in the Federal Register on August 30, 2016 (81 FR 59544). The NPRM was prompted by reports of damaged vapor seals, block seals, and heat shield seals on the outboard pylons between the engine strut and aft fairing. The NPRM proposed to require repetitive inspections for heat damage of the vapor seals between the engine strut and aft fairing, and replacement of the seals with new seals if necessary. We are issuing this AD to detect and correct heat damage to the vapor seals between the engine strut and aft fairing. Such damage could allow flammable fluid leakage out of the aft fairing, which could result in an uncontrolled fire in the engine strut.

We gave the public the opportunity to participate in developing this AD. The following presents the comment received on the NPRM and the FAA's response to the comment.

Boeing asked that we change the unsafe condition in the SUMMARY and Discussion sections and in paragraph (e) of the proposed AD from “Such damage could allow flammable fluid leakage into the aft fairing...” to “Such damage could allow flammable fluid leakage out of the aft fairing...” Boeing stated that the aft fairing is a flammable leakage zone, and escaping fluid passing the vapor seal is leaving the aft fairing.

We agree with the commenter for the reason provided. However, the unsafe condition is not carried over into the SUMMARY section of this final rule. We have changed the unsafe condition in the Discussion section and paragraph (e) of this AD accordingly.

We reviewed the relevant data, considered the comment received, and determined that air safety and the public interest require adopting this AD with the change described previously and minor editorial changes. We have determined that these minor changes:

• Are consistent with the intent that was proposed in the NPRM for correcting the unsafe condition; and

• Do not add any additional burden upon the public than was already proposed in the NPRM.

We also determined that these changes will not increase the economic burden on any operator or increase the scope of this AD.

We reviewed Boeing Alert Service Bulletin 747-54A2246, dated February 5, 2016. The service information describes procedures for repetitive inspections for heat damage of the vapor seals between the engine strut and aft fairing, and replacement of the seals with new seals. 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.

We estimate that this AD affects 10 airplanes of U.S. registry. We estimate the following costs to comply with this AD:

We estimate the following costs to do any necessary seal replacement that will be required based on the results of the vapor seal inspection. We have no way of determining the number of aircraft that might need these seal replacements.

According to the manufacturer, some of the costs of this AD may be covered under warranty, thereby reducing the cost impact on affected individuals. We do not control warranty coverage for affected individuals. As a result, we have included all costs in our 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.

We are 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) Is not a “significant rule” under DOT Regulatory Policies and Procedures (44 FR 11034, February 26, 1979),

(3) Will not affect intrastate aviation in Alaska, and

(4) 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 (AD):