AD 2020-19-04 Requires Removing Certain Main Gearbox (MGB) Input Modules From Service

The FAA is adopting a new airworthiness directive (AD) for Leonardo S.p.a. (Leonardo) Model AB139 and AW139 helicopters.

This AD requires removing certain main gearbox (MGB) input modules from service. This AD was prompted by the discovery that a batch of duplex bearings, which are installed on the MGB input modules, are defective. The actions of this AD are intended to address an unsafe condition on these products. This AD is effective October 15, 2020.

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 Model AB139 and AW139 helicopters with certain serial-numbered MGB input modules part number (P/N) 3K6320A00135 or P/N 3K6320A00136 installed.

The NPRM published in the Federal Register on June 8, 2020 (85 FR 35018). The NPRM proposed to require removing the affected MGB input modules from service and prohibit installing the affected MGB input modules. The proposed requirements were intended to address defective duplex bearings on MGB input modules, which could result in damage including corrosion and cracking, which could result in excessive heat of the input module duplex ball bearing inner race and subsequent loss of engine power and loss of helicopter control.

The NPRM was prompted by EASA AD No. 2016-0255R1, dated January 17, 2017 (EASA AD 2016-0255R1), issued by EASA, which is the Technical Agent for the Member States of the European Union, to correct an unsafe condition for Leonardo (formerly Finmeccanica S.p.A., AgustaWestland Philadelphia Corporation, Agusta Aerospace Corporation) Model AB139 and AW139 helicopters with certain serial-numbered MGB input modules P/N 3K6320A00135 or P/N 3K6320A00136 installed. EASA advises that the supplier of a batch of duplex bearings installed on MGB input modules reported that the bearings were defective, due to a quality control issue. This condition, if not detected or corrected, could lead to damage of the input module duplex ball bearing inner race, possibly resulting in loss of engine power and reduced control of the helicopter. Accordingly, EASA AD 2016-0255R1 requires removing the affected MGB input modules from service.

FMI: www.regulations.gov