AD 99-04-05
Applicability
| Type | Manufacturer | Model | Details |
|---|---|---|---|
| engine | Pratt & Whitney Division | JT9D-59A | Airworthiness Directives; Pratt & Whitney JT9D Series Turbofan Engines |
| engine | Pratt & Whitney Division | JT9D-70A | Airworthiness Directives; Pratt & Whitney JT9D Series Turbofan Engines |
| engine | Pratt & Whitney Division | JT9D-7Q | Airworthiness Directives; Pratt & Whitney JT9D Series Turbofan Engines |
| engine | Pratt & Whitney Division | JT9D-7Q3 | Airworthiness Directives; Pratt & Whitney JT9D Series Turbofan Engines |
Unsafe Condition
Diffuser case rupture due to cracks in the rear skirt around the dog bone-shaped bosses, which can result in uncontained engine failure and damage to the aircraft.
AI-generated summary from the source AD text. Verify against the official source before acting.
Required Actions
Perform fluorescent penetrant inspection (FPI) of the diffuser case rear skirt for cracks, paying particular attention to areas around the dog bone-shaped bosses. If cracks are found, blend down to minimum wall thickness, perform subsequent FPI, and if cracks remain, remove the diffuser case from service and replace with a serviceable part. Polishing and shotpeening are required if cracks are removed.
AI-generated summary from the source AD text. Verify against the official source before acting.
Compliance Time
At the next piece-part exposure of the diffuser case after the effective date of this AD (April 12, 1999).
AI-generated summary from the source AD text. Verify against the official source before acting.
Affected Aircraft
Pratt & Whitney Model JT9D-7Q, -7Q3, -59A, and -70A turbofan engines with diffuser cases part numbers 772173, 772173-001, 772173-002, 782222, 782222-001, and 782222-002.
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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