AD 2021-13-01 Prompted By Reports Of Missing Lock Wire And Loose Fasteners

The FAA is adopting a new airworthiness directive (AD) for Leonardo S.p.a. (Type Certificate previously held by Agusta S.p.A.) Model AB139 and AW139 helicopters and Leonardo S.p.a. (Type Certificate previously held by AgustaWestland S.p.A.) Model AW189 helicopters.

This AD was prompted by reports of missing lock wire and loose fasteners. This AD requires a one-time inspection of the main rotor (M/R) slip ring and depending on the outcome, removing the M/R slip ring from service, removing screws and washers from service, applying torque, installing lock wire, and re-identifying the M/R slip ring. This AD also prohibits the installation of certain M/R slip rings. The FAA is issuing this AD to address the unsafe condition on these products. This AD is effective August 3, 2021.

Supplementary Information: The FAA issued a notice of proposed rulemaking (NPRM) to amend 14 CFR part 39 by adding an AD that would apply to Leonardo S.p.a. (Type Certificate previously held by Agusta S.p.A.) Model AB139 and AW139 helicopters and Leonardo S.p.a. (Type Certificate previously held by AgustaWestland S.p.A.) Model AW189 helicopters with an M/R slip ring part number (P/N) 4G6220V00151 with a serial number (S/N) up to and including S/N 0141, except those marked with an “L” following the S/N, installed. The NPRM published in the Federal Register on April 19, 2021 (86 FR 20338). In the NPRM, the FAA proposed to require, with the M/R slip ring removed, inspecting each screw and double-twist lock wire of the upper (connecter) end and lower (pigtail or standpipe) end fasteners of the M/R slip ring. Depending on the outcome, the NPRM proposed to require marking the M/R slip ring; removing the M/R slip ring from service; or removing screws and washers, lock wire, and ferrule ended safety cable from service, installing new screws and washers, applying torque, installing double-twist lock wire, and marking the M/R slip ring. The NPRM also proposed to prohibit the installation of an affected M/R slip ring unless the proposed requirements have been completed.

The NPRM was prompted by EASA AD 2017-0083, dated May 10, 2017 (EASA AD 2017-0083), to correct an unsafe condition for Leonardo S.p.A. (formerly Finmeccanica S.p.A, AgustaWestland S.p.A., Agusta S.p.A), AgustaWestland Philadelphia Corporation (formerly Agusta Aerospace Corporation) Model AB139 and AW139 helicopters, and EASA AD 2017-0087, dated May 12, 2017 (EASA AD 2017-0087), to correct the same unsafe condition for Leonardo S.p.A. Helicopters (formerly Finmeccanica S.p.A, AgustaWestland S.p.A.) Model AW189 helicopters, each issued by EASA, which is the Technical Agent for the Member States of the European Union. EASA advises of reports of missing lock wire and loose fasteners found during inspections of the M/R slip ring of Model AW139 helicopters. EASA also advises that the same part-numbered M/R slip ring may also be installed on Model AW189 helicopters. Model AB139 helicopters may also be affected by this unsafe condition due to having the same type design as Model AW139 helicopters. EASA ADs 2017-0083 and 2017-0087 require a one-time visual inspection of the M/R slip ring fastener installation, and depending on the outcome, replacing the M/R slip ring, replacing fasteners, applying torque, installing lock wire, and re-identifying the M/R slip ring. EASA ADs 2017-0083 and 2017-0087 also prohibit installation of an affected M/R slip ring. EASA states, this condition, if not detected and corrected, could lead to failure of the M/R slip ring bearing inner race, possibly resulting in damage to drive system components and subsequent reduced control of the helicopter.

FMI: www.regulations.gov