AD 75-07-01
Applicability
| Type | Manufacturer | Model | Details |
|---|---|---|---|
| aircraft | Bell Helicopter Textron, Inc. | 212 | Airworthiness Directives; Bell Model 212 Helicopters |
Unsafe Condition
Improperly manufactured nuts (P/N 212-040-631-1) with specific serial numbers (A20-00427, A20-00469, A20-00472, A20-00475, A20-00476, A20-00477, A20-00478) on the main drive shaft assembly may fail, leading to high frequency vibration and potential loss of main drive shaft function.
AI-generated summary from the source AD text. Verify against the official source before acting.
Required Actions
Inspect the exposed nut for serial numbers listed in the AD; remove and replace any nuts with the specified serial numbers using an acceptable nut per maintenance manual instructions. Notify Bell Helicopter Company or FAA if non-compliant nuts are found.
AI-generated summary from the source AD text. Verify against the official source before acting.
Compliance Time
Within the next 25 hours' time in service after the effective date of this AD, or before next flight if an unusual high frequency vibration is detected.
AI-generated summary from the source AD text. Verify against the official source before acting.
Affected Aircraft
Bell Helicopter Textron, Inc. Model 212 helicopters, serial numbers 30501 through 30658 and 30671.
AI-generated summary from the source AD text. Verify against the official source before acting.
Source: Official FAA Source ↗
Retrieved: Apr 8, 2026
Rights: U.S. Government Public Domain
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