AD 57-05-04
Applicability
| Type | Manufacturer | Model | Details |
|---|---|---|---|
| engine | Pratt & Whitney Division | Military R-985 Series | PRATT & WHITNEY Model Wasp Jr. and Military R-985 Series Engines |
| engine | Pratt & Whitney Division | Wasp Jr. A | PRATT & WHITNEY Model Wasp Jr. and Military R-985 Series Engines |
| engine | Pratt & Whitney Division | Wasp Jr. B-4 | PRATT & WHITNEY Model Wasp Jr. and Military R-985 Series Engines |
| engine | Pratt & Whitney Division | Wasp Jr. B-5 | PRATT & WHITNEY Model Wasp Jr. and Military R-985 Series Engines |
| engine | Pratt & Whitney Division | Wasp Jr. SB | PRATT & WHITNEY Model Wasp Jr. and Military R-985 Series Engines |
| engine | Pratt & Whitney Division | Wasp Jr. SB-2 | PRATT & WHITNEY Model Wasp Jr. and Military R-985 Series Engines |
| engine | Pratt & Whitney Division | Wasp Jr. SB-3 | PRATT & WHITNEY Model Wasp Jr. and Military R-985 Series Engines |
| engine | Pratt & Whitney Division | Wasp Jr. T1B | PRATT & WHITNEY Model Wasp Jr. and Military R-985 Series Engines |
| engine | Pratt & Whitney Division | Wasp Jr. T1B2 | PRATT & WHITNEY Model Wasp Jr. and Military R-985 Series Engines |
| engine | Pratt & Whitney Division | Wasp Jr. T1B3 | PRATT & WHITNEY Model Wasp Jr. and Military R-985 Series Engines |
Unsafe Condition
Crankshaft cracking at the thrust nut threads and possible loss of the propeller in flight due to insufficient strength from previous AD rework.
AI-generated summary from the source AD text. Verify against the official source before acting.
Required Actions
At next overhaul, either perform special magnetic inspection, shadowgraph inspection, radius adjustment, and shotpeening on existing crankshafts (except those marked '14F-56' or new designs) or install new design crankshafts with part numbers 261278, 261279, or 264164. If oil leakage occurs, inspect for cracks using dye penetrant and optical glass; replace crankshaft if cracks are found.
AI-generated summary from the source AD text. Verify against the official source before acting.
Compliance Time
at next overhaul
AI-generated summary from the source AD text. Verify against the official source before acting.
Affected Aircraft
Pratt & Whitney Model Wasp Jr. and Military R-985 Series Engines, except those used in helicopters.
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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