AD 2021-07-16
Applicability
| Type | Manufacturer | Model | Details |
|---|---|---|---|
| aircraft | Leonardo | S.p.a. | Airworthiness Directives; Leonardo S.p.a. Helicopters |
Unsafe Condition
A crack was found in a spiral bevel gear part number (P/N) 204-040-701-103 during a scheduled inspection of a main rotor (M/R) transmission P/N 212-040-001-59. The initial investigation determined that the crack originated from the bottom of one of the 32 threaded holes. Other spiral bevel gears manufactured with the same process as the defective one could be affected by the same issue. This condition, if not addressed, could lead to failure of the M/R transmission and possible loss of control of the helicopter.
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Required Actions
A one-time visual inspection and a recurring fluorescent magnetic particle inspection (FMPI) of certain serial-numbered spiral bevel gears P/N 204-040-701-103 for a crack, and if there is a crack, removing the spiral bevel gear from service. Installing an affected spiral bevel gear unless it has previously passed an FMPI within less than 300 hours time-in-service.
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Compliance Time
Before further flight
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Affected Aircraft
Leonardo S.p.A. Model AB412 helicopters, all serial numbers (S/Ns) up to S/N 25669 inclusive, with certain serial-numbered spiral bevel gears P/N 204-040-701-103 installed.
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Source: Official FAA Source ↗
Retrieved: Apr 4, 2026
Rights: U.S. Government Public Domain
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