AD 78-17-08
Applicability
| Type | Manufacturer | Model | Details |
|---|---|---|---|
| engine | Pratt & Whitney Division | JT9D-20 | PRATT & WHITNEY AIRCRAFT Model JT9D-3, -3A, -7, -7A, -7AH, -7H, -7F, -7J, -20, and -20B Engines |
| engine | Pratt & Whitney Division | JT9D-3A | PRATT & WHITNEY AIRCRAFT Model JT9D-3, -3A, -7, -7A, -7AH, -7H, -7F, -7J, -20, and -20B Engines |
| engine | Pratt & Whitney Division | JT9D-7 | PRATT & WHITNEY AIRCRAFT Model JT9D-3, -3A, -7, -7A, -7AH, -7H, -7F, -7J, -20, and -20B Engines |
| engine | Pratt & Whitney Division | JT9D-7A | PRATT & WHITNEY AIRCRAFT Model JT9D-3, -3A, -7, -7A, -7AH, -7H, -7F, -7J, -20, and -20B Engines |
| engine | Pratt & Whitney Division | JT9D-7AH | PRATT & WHITNEY AIRCRAFT Model JT9D-3, -3A, -7, -7A, -7AH, -7H, -7F, -7J, -20, and -20B Engines |
| engine | Pratt & Whitney Division | JT9D-7F | PRATT & WHITNEY AIRCRAFT Model JT9D-3, -3A, -7, -7A, -7AH, -7H, -7F, -7J, -20, and -20B Engines |
| engine | Pratt & Whitney Division | JT9D-7H | PRATT & WHITNEY AIRCRAFT Model JT9D-3, -3A, -7, -7A, -7AH, -7H, -7F, -7J, -20, and -20B Engines |
| engine | Pratt & Whitney Division | JT9D-7J | PRATT & WHITNEY AIRCRAFT Model JT9D-3, -3A, -7, -7A, -7AH, -7H, -7F, -7J, -20, and -20B Engines |
Unsafe Condition
Failures of fifteenth stage compressor disks due to low cycle fatigue cracking.
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Required Actions
Inspect disks in accordance with Pratt & Whitney Aircraft Alert Service Bulletin 4908. Reinspect disks using specified methods and intervals: Rim Access Ultrasonic Inspection requires reinspections every 600 cycles; HPC Central Cavity Access or Detail Access Eddy Current Inspection requires reinspections every 1600 cycles. Remove disks with cracks prior to further flight.
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Compliance Time
Compliance required as indicated, unless already accomplished.
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Affected Aircraft
Pratt & Whitney Aircraft JT9D-3, -3A, -7, -7A, -7AH, -7H, -7F, -7J, -20, and -20B engines containing fifteenth stage compressor disk, P/N 672915 or P/N 658615.
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Source: Official FAA Source ↗
Retrieved: Apr 8, 2026
Rights: U.S. Government Public Domain
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