AD 2018-15-03

This AD is effective August 27, 2018.

The Director of the Federal Register approved the incorporation by reference of a certain publication listed in this AD as of August 27, 2018.

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 referenced service information at the FAA, Transport Standards 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 on the internet at http://www.regulations.gov by searching for and locating Docket No. FAA-2018-0114.

Tak Kobayashi, Aerospace Engineer, Propulsion Section, FAA, Seattle ACO Branch, 2200 South 216th St., Des Moines, WA; phone: 206-231-3553; email: Takahisa.Kobayashi@faa.gov.

We issued a notice of proposed rulemaking (NPRM) to amend 14 CFR part 39 by adding an AD that would apply to The Boeing Company Model 787 series airplanes powered by Rolls Royce Trent 1000 engines. The NPRM published in the Federal Register on February 23, 2018 (83 FR 8017). The NPRM was prompted by reports of failures of the IFS forward upper fire seal and damage to thermal insulation blankets in the forward upper area of the TR. The NPRM proposed to require an inspection to determine the part number of the IFS forward upper fire seal, and applicable on-condition actions.

We are issuing this AD to prevent failure of the IFS forward upper fire seal, which causes the loss of seal pressurization and allows fan bypass air to enter the engine core compartment. Fan bypass air entering the engine core compartment could degrade the ability to detect and extinguish an engine fire, resulting in an uncontrolled fire. Furthermore, fan bypass air entering the engine core compartment could cause damage to the TR insulation blanket, resulting in thermal damage to the TR inner wall, the subsequent release of engine exhaust components, and consequent damage to critical areas of the airplane.

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

Boeing supported the intent of the NPRM.

An anonymous commenter requested that an additional action be included in the proposed AD. The commenter proposed that Boeing develop an inspection of the thermal blankets and fire seals to ensure the integrity and safe operation of these components. The commenter expressed concern that a thermal blanket could fail due to insufficient sealing by the fire seals that have incorporated the modification mandated by this AD. The modification of the fire seals is specified in Boeing Alert Service Bulletin B787-81205-SB780033-00, Issue 001, dated November 1, 2017 (“BASB B787-81205-SB780033-00, Issue 001”).

The commenter stated that the post-modification fire seals are still failing. The commenter is aware of 30 findings of fire seal/thermal blanket damage across a fleet size of 16 airplanes. The commenter noted that there were 18 findings prior to incorporation of the modification of the fire seals specified in BASB B787-81205-SB780033-00, Issue 001, and 12 findings after incorporation of that modification. The commenter is concerned that the unsafe condition addressed by this AD could still exist after accomplishment of the mandatory modification.

We do not agree with the commenter's request. We do not want to delay the publication of this AD by adding a new inspection requirement that will require additional time for public comment. We have determined that the modification of the fire seals required by this AD addresses the design issue of the fire seal end cap that resulted in failure of the IFS forward upper fire seal and damage to the thermal blanket. We are aware of operator reports that damage to the IFS forward upper fire seal and thermal blanket has been discovered on airplanes on which the modification specified in BASB B787-81205-SB780033-00, Issue 001, has been done. The airplane manufacturer is investigating the root cause of this damage and, when the root cause is identified, we may consider further rulemaking at that time. We have not changed this AD in this regard.

We reviewed the relevant data, considered the comments received, and determined that air safety and the public interest require adopting this final rule as proposed, except for minor editorial changes. We have determined that these minor changes:

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

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

Boeing has issued Boeing Alert Service Bulletin B787-81205-SB780033-00, Issue 001, dated November 1, 2017. This service information describes procedures for an inspection to determine the part number of the IFS forward upper fire seal and applicable on-condition actions. 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 13 airplanes of U.S. registry. We estimate the following costs to comply with this AD:

We estimate the following costs to do any necessary on-condition actions that will be required. We have 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.

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 is issued in accordance with authority delegated by the Executive Director, Aircraft Certification Service, as authorized by FAA Order 8000.51C. In accordance with that order, issuance of ADs is normally a function of the Compliance and Airworthiness Division, but during this transition period, the Executive Director has delegated the authority to issue ADs applicable to transport category airplanes and associated appliances to the Director of the System Oversight Division.

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):