AD 2018-25-15

This AD is effective January 22, 2019.

The Director of the Federal Register approved the incorporation by reference of certain publication listed in this AD as of January 22, 2019.

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, 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-2018-0803.

Muoi Vuong, Aerospace Engineer, Airframe Section, FAA, Los Angeles ACO Branch, 3960 Paramount Boulevard, Lakewood, CA 90712-4137; phone: 562-627-5205; fax: 562-627-5210; email: muoi.vuong@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 727 airplanes. The NPRM published in the Federal Register on September 28, 2018 (83 FR 49017). The NPRM was prompted by a report of cracking in the inboard lower flange and adjacent web near the forward attachment of the outboard flap track at a certain position on a Model 737-300 airplane. The flap tracks of Model 737-300 airplanes are similar to the flap tracks of Model 727 airplanes. The NPRM proposed to require repetitive detailed inspections and surface HFEC inspections of each outboard flap track at certain positions for any crack and discrepancy, and applicable on-condition actions.

We are issuing this AD to address the inability of a principal structural element to sustain required flight loads, which could result in loss of the outboard trailing edge flap and reduced controllability of the airplane.

We gave the public the opportunity to participate in developing this final rule. We have considered the comment received. Boeing indicated its support for the NPRM.

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.

We reviewed Boeing Alert Requirements Bulletin 727-57A0188 RB, dated May 31, 2018. The service information describes procedures for repetitive detailed inspections for discrepancies and surface HFEC inspections for cracks of each outboard flap track at positions 1, 2, 7, and 8, and applicable on-condition actions. On-condition actions include repairs and installation of a new or serviceable flap track. 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 16 airplanes of U.S. registry. We estimate the following costs to comply with this AD:

We have received no definitive data that would enable us to provide cost estimates for the on-condition actions specified in this AD.

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):