AD 78-08-13
Applicability
| Type | Manufacturer | Model | Details |
|---|---|---|---|
| engine | Pratt & Whitney Division | JT9D-3A | PRATT & WHITNEY AIRCRAFT Models JT9D-3, -3A, -7, -7A, -7H, -7AH, -7F, and -7J Engines |
| engine | Pratt & Whitney Division | JT9D-7 | PRATT & WHITNEY AIRCRAFT Models JT9D-3, -3A, -7, -7A, -7H, -7AH, -7F, and -7J Engines |
| engine | Pratt & Whitney Division | JT9D-7A | PRATT & WHITNEY AIRCRAFT Models JT9D-3, -3A, -7, -7A, -7H, -7AH, -7F, and -7J Engines |
| engine | Pratt & Whitney Division | JT9D-7AH | PRATT & WHITNEY AIRCRAFT Models JT9D-3, -3A, -7, -7A, -7H, -7AH, -7F, and -7J Engines |
| engine | Pratt & Whitney Division | JT9D-7F | PRATT & WHITNEY AIRCRAFT Models JT9D-3, -3A, -7, -7A, -7H, -7AH, -7F, and -7J Engines |
| engine | Pratt & Whitney Division | JT9D-7H | PRATT & WHITNEY AIRCRAFT Models JT9D-3, -3A, -7, -7A, -7H, -7AH, -7F, and -7J Engines |
| engine | Pratt & Whitney Division | JT9D-7J | PRATT & WHITNEY AIRCRAFT Models JT9D-3, -3A, -7, -7A, -7H, -7AH, -7F, and -7J Engines |
Unsafe Condition
Main gearbox fires due to internal bearing failures.
AI-generated summary from the source AD text. Verify against the official source before acting.
Required Actions
Inspect magnetic plug within 300 hours time in service after the effective date and every 300 hours thereafter for gearboxes with over 5,000 hours since new or last inspection. For gearboxes with 5,000 hours or less, inspect within 650 hours or at 5,300 hours total time, whichever comes first. If spalled particles are found, reinspect within 50 hours, then 25 hours if particles persist, and remove gearbox from service if particles remain.
AI-generated summary from the source AD text. Verify against the official source before acting.
Compliance Time
Compliance required as indicated, unless already accomplished.
AI-generated summary from the source AD text. Verify against the official source before acting.
Affected Aircraft
Pratt & Whitney Aircraft Models JT9D-3, -3A, -7, -7A, -7H, -7AH, -7F, and -7J engines.
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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