AD 92-09-05
Applicability
| Type | Manufacturer | Model | Details |
|---|---|---|---|
| aircraft | Bell Helicopter Textron, Inc. | 212 | Airworthiness Directives; BELL HELICOPTER TEXTRON, INC. Model 212 and 412 Helicopters |
| aircraft | Bell Helicopter Textron, Inc. | 412 | Airworthiness Directives; BELL HELICOPTER TEXTRON, INC. Model 212 and 412 Helicopters |
Unsafe Condition
Failure of the combining gearbox due to corrosion fretting on the engine-to-driveshaft coupling adapter splines or excessive dimensional changes, which could result in loss of power to the main rotor system.
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Required Actions
Within 20 hours' time in service after the effective date, inspect the torque on the engine-to-driveshaft coupling adapter retaining nut. If the nut rotates before 125 foot-pounds torque, further actions include inspecting and replacing the adapter if corrosion fretting or dimensional exceedances are found, inspecting engine output splines for fretting or dimensional issues requiring gearbox overhaul, and reinstalling the adapter with specific torque procedures and lock washer checks. Compliance with specified service bulletins also fulfills the AD.
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Compliance Time
within the next 20 hours' time in service after the effective date of this AD
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Affected Aircraft
Bell Helicopter Textron, Inc. Model 212 helicopters, serial numbers 35001 through 35037, 35039, and 35040; and Model 412 helicopters, serial numbers 36001 through 36025, and 36027.
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Source: Official FAA Source ↗
Retrieved: Apr 8, 2026
Rights: U.S. Government Public Domain
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