2021-27539

Document Headings Document headings vary by document type but may contain the following: • the agency or agencies that issued and signed a document • the number of the CFR title and the number of each part the document amends, proposes to amend, or is directly related to • the agency docket number / agency internal file number • the RIN which identifies each regulatory action listed in the Unified Agenda of Federal Regulatory and Deregulatory Actions See the Document Drafting Handbook for more details. Department of Transportation Federal Aviation Administration • 14 CFR Part 39 • [Docket No. FAA-2021-0951; Project Identifier AD-2021-01047-R; Amendment 39-21804; AD 2021-23-06] • RIN 2120-AA64 AGENCY: Federal Aviation Administration (FAA), DOT. ACTION: Final rule; request for comments. SUMMARY: The FAA is adopting a new airworthiness directive (AD) for various Model 234 and Model CH-47D helicopters. This AD was prompted by two reports of mechanical failures of the longitudinal cyclic trim actuator (LCTA). This AD requires determining the maintenance history, and hours time-in-service (TIS) and number of lift cycles for each LCTA since last overhaul, and then requires initial and repetitive overhauls of each LCTA based on that maintenance and service history. This AD also prohibits installing an LCTA unless it meets certain requirements. Finally, this AD requires reporting certain information to the FAA. The FAA is issuing this AD to address the unsafe condition on these products. DATES: This AD is effective January 4, 2022. The FAA must receive comments on this AD by February 3, 2022. ADDRESSES: You may send comments, using the procedures found in 14 CFR 11.43 and 11.45, by any of the following methods: • Federal eRulemaking Portal: Go to https://www.regulations.gov. Follow the instructions for submitting comments. • Fax: (202) 493-2251. • Mail: U.S. Department of Transportation, Docket Operations,M-30, West Building Ground Floor, Room W12-140, 1200 New Jersey Avenue SE, Washington, DC 20590. • Hand Delivery: Deliver to Mail address above between 9 a.m. and 5 p.m., Monday through Friday, except Federal holidays. Examining the AD Docket You may examine the AD docket at https://www.regulations.gov by searching for and locating Docket No. FAA-2021-0951; or in person at Docket Operations between 9 a.m. and 5 p.m., Monday through Friday, except Federal holidays. The AD docket contains this final rule, any comments received, and other information. The street address for the Docket Operations is listed above. FOR FURTHER INFORMATION CONTACT: David Herron, Aerospace Engineer, Systems & Equipment Section, Seattle ACO Branch, FAA, 2200 South 216th St., Des Moines, WA 98198; phone and fax: (206) 231-3554; email david.herron@faa.gov. SUPPLEMENTARY INFORMATION: Background The FAA received two reports of mechanical failure of an LCTA, the function of which is to constrain and control the non-rotating swashplate. In both failures, which occurred on Model CH-47D helicopters, the flight crew was forced to make an emergency landing as they had difficulty controlling the helicopter. Model 234 and Model CH-47D helicopters both have the same LCTA installed, with two installed on each rotorcraft. Investigation as to the root cause of these failures has determined that inadequate maintenance overhaul procedures and scheduled overhaul intervals for this critical flight component with a single structural load path likely contributed to this unsafe condition. One event occurred due to excessive wear of the acme screw threads from de…

Fonte: Federal Register (federalregister.gov). Texto original em inglês. Conteúdo sanitizado por segurança.