AD 49-47-02
Applicability
| Type | Manufacturer | Model | Details |
|---|---|---|---|
| aircraft | Scotts-Bell 47 Inc | 47B | Airworthiness Directives; Bell Model 47B, 47B3, 47D, and 47D1 Helicopters |
| aircraft | Scotts-Bell 47 Inc | 47B3 | Airworthiness Directives; Bell Model 47B, 47B3, 47D, and 47D1 Helicopters |
| aircraft | Scotts-Bell 47 Inc | 47D | Airworthiness Directives; Bell Model 47B, 47B3, 47D, and 47D1 Helicopters |
| aircraft | Scotts-Bell 47 Inc | 47D1 | Airworthiness Directives; Bell Model 47B, 47B3, 47D, and 47D1 Helicopters |
Unsafe Condition
Failures of the tail rotor drive system, including wear, cracks, chips, brinelling, dents, cuts, fatigue signs, and cracks at thread roots of the sleeve, could result in loss of tail rotor drive function.
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Required Actions
Inspect bearings, shaft surfaces, and sleeve for wear, cracks, chips, brinelling, dents, cuts, fatigue signs, and cracks at thread roots via visual and magnaflux inspections every 50 hours starting with the next 25 hours of operation. Install redesigned drive shafts (P/N 47-644-126, 47-644-181) and spline couplings (P/N 47-644-177, 47-644-130) by February 15, 1950.
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Compliance Time
Not later than the next 25 hours of operation and at each 50-hour period thereafter until modifications are incorporated. Modifications must be completed by February 15, 1950.
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Affected Aircraft
Scotts-Bell 47 Inc Model 47B, 47B3, 47D, and Model 47D1 serial numbers 145 through 164.
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Source: Official FAA Source ↗
Retrieved: Apr 8, 2026
Rights: U.S. Government Public Domain
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