AD 2021-08-17 Prompted By The Discovery Of A Main Gearbox (MGB) With Worn Ramps And Broken Roller Cages

The FAA is adopting a new airworthiness directive (AD) for Airbus Helicopters Model AS332L2 helicopters. This AD was prompted by the discovery of a main gearbox (MGB) with worn ramps and broken roller cages. This AD requires installing a placard on the pilot instrument panel and replacing certain MGBs. The FAA is issuing this AD to address the unsafe condition on these products. This AD becomes effective May 12, 2021.

Supplementary Information: EASA, which is the Technical Agent for the Member States of the European Union, issued EASA AD 2020-0141R1, dated July 30, 2020 (EASA AD 2020-0141R1) to correct an unsafe condition for Airbus Helicopters (formerly Eurocopter France, Aerospatiale) Model AS 332 L2 helicopters. EASA AD 2020-0141R1 advises that, during an overhaul of a Model EC 225 LP helicopter with an MGB part number (P/N) 332A323001.XX equipped with main reduction gear module P/N 332A323011.XX in post-modification (mod) 07-53016 configuration, where XX represents any number, wear was detected on ramps and roller cages. Mod 07-53016 corresponds to free wheel shaft P/N 332A322191.20. EASA states that an investigation is currently ongoing to determine the root cause of the occurrence and that Model AS 332 L2 helicopters could be affected by the same failure mechanism due to design similarity. According to EASA, this condition, if not corrected, could lead to reduced capacity to transfer one engine inoperative (OEI) power by the right engine following an in-flight shut down of the left engine, resulting in reduced control of the helicopter.

EASA further states that Airbus Helicopters issued service information to provide instructions to introduce operational restrictions regarding training flights involving OEI and replacement of the affected MGB in order to allow Airbus Helicopters to accomplish a one-time wear inspection of the free wheel shaft. Consequently, EASA issued an AD to require an operational limitation for OEI training flights by installing placards and to require replacing the MGB if it has a right free wheel shaft P/N 332A322191.20. EASA revised its original AD and issued EASA AD 2020-0141R1 after Airbus Helicopters issued a change to its service information to clarify the wording of the operational limitation in the placard. EASA states that EASA AD 2020-0141R1 is considered an interim action and that further AD action may follow.

FMI: www.regulations.gov