AD 78-08-07
Applicability
| Type | Manufacturer | Model | Details |
|---|---|---|---|
| engine | Pratt & Whitney Division | Military R-985 Series | PRATT & WHITNEY AIRCRAFT Model R985 Engines |
| engine | Pratt & Whitney Division | Wasp Jr. A | PRATT & WHITNEY AIRCRAFT Model R985 Engines |
| engine | Pratt & Whitney Division | Wasp Jr. B-4 | PRATT & WHITNEY AIRCRAFT Model R985 Engines |
| engine | Pratt & Whitney Division | Wasp Jr. B-5 | PRATT & WHITNEY AIRCRAFT Model R985 Engines |
| engine | Pratt & Whitney Division | Wasp Jr. SB | PRATT & WHITNEY AIRCRAFT Model R985 Engines |
| engine | Pratt & Whitney Division | Wasp Jr. SB-2 | PRATT & WHITNEY AIRCRAFT Model R985 Engines |
| engine | Pratt & Whitney Division | Wasp Jr. SB-3 | PRATT & WHITNEY AIRCRAFT Model R985 Engines |
| engine | Pratt & Whitney Division | Wasp Jr. T1B | PRATT & WHITNEY AIRCRAFT Model R985 Engines |
| engine | Pratt & Whitney Division | Wasp Jr. T1B2 | PRATT & WHITNEY AIRCRAFT Model R985 Engines |
| engine | Pratt & Whitney Division | Wasp Jr. T1B3 | PRATT & WHITNEY AIRCRAFT Model R985 Engines |
Unsafe Condition
Cylinder head separation from the barrel
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Required Actions
Visually inspect cylinder heads in accordance with Service Bulletin No. 1785. Remove visibly cracked cylinders and those with black combustion leakage before further flight. Inspect all cylinder assemblies prior to installation using ultrasonic testing or equivalent method. Remove cylinders with cracks exceeding specified limits.
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Compliance Time
Within 50 hours time in service after AD effective date for non-ultrasonically inspected cylinders, and within 150 hours time in service for ultrasonically inspected cylinders. Subsequent inspections at intervals not exceeding 100 or 150 hours time in service respectively.
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Affected Aircraft
Pratt & Whitney Aircraft Model R985 engines including Military R-985 Series, Wasp Jr. A, B-4, B-5, SB, SB-2, and others as listed.
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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