Airworthiness Directive · Amendment 39-21748 · Main rotor gearbox
Leonardo S.p.a. Helicopters
Superseded. A later AD replaced this one: AD 2022-27-03. Comply with the one in force.
This AD applies to Leonardo S.p.a. Model AB139 and AW139 helicopters, certificated in any category, without main gearbox (MGB) spherical bearing lock nut (lock nut) part number (P/N) 3G6320A09152 installed and with:
(1) MGB P/N 3G6320A00131, 3G6320A00132, 3G6320A00133, 3G6320A00134, 3G6320A00135, 3G6320A00136, 3G6320A22031, 4G6320A00132, or 4G6320A00133 installed, or
(2) MGB P/N 3G320A00133 with serial number (S/N) M23, or MGB P/N 3G6320A00134, with S/N M6, N76, N92, P124, P129, P131, P162, P184, Q230, Q243, Q249, R272, V21, V39, V96, V163, V211, V241, V272, V281, V384, V386, or V622 installed, or
(3) MGB P/N 3G6320A00136 with S/N AW1, AW2, AW3, AW5, or AW10 installed.
The FAA is adopting a new airworthiness directive (AD) for certain Leonardo S.p.a. Model AB139 and AW139 helicopters. This AD was prompted by a report of several occurrences of a cracked main gearbox (MGB) spherical bearing lock nut (lock nut). This AD requires removing from service a certain part-numbered MGB lock nut that is installed on certain part-numbered MGBs and replacing it with newly designed MGB lock nut. This AD also prohibits installing any MGB with the affected MGB lock nut and prohibits installing any affected MGB lock nut on any helicopter. The FAA is issuing this AD to address the unsafe condition on these products.
(1) Within 100 hours time-in-service, or during the next scheduled MGB overhaul, whichever occurs first after the effective date of this AD, remove each MGB lock nut P/N 3G6320A09151 from service and replace with MGB lock nut P/N 3G6320A09152 in accordance with Annex A, steps 1 through 17, of Leonardo Helicopters Alert Service Bulletin No. 139-609, Revision A, dated April 13, 2021, except you are not required to send parts to Leonardo Helicopters.
Note to paragraph (g)(1): Leonardo Helicopters service information refers to an MGB lock nut as a ring nut.
(2) As of the effective date of this AD, do not install any MGB having MGB lock nut P/N 3G630A09151 on any helicopter, and do not install any MGB lock nut P/N 3G630A09151 on any helicopter.
The aircraft, engines and makers this AD names, by the model designations in its text. A model listed here may still be outside the AD's serial ranges.
Aircraft
