AD 99-14-08
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
Uncontained failure of the sixth stage low pressure turbine (LPT) inner airseal due to cracks less than one inch in length.
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Required Actions
Rework the sixth stage LPT inner airseal knife edge diameters and rear retaining wing prior to further flight. Eddy current or borescope inspect for cracks at specified intervals, remove and replace cracked airseals not meeting continue in service criteria. Install improved 6th stage LPT inner airseal per SB 6054 to terminate inspections.
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Compliance Time
Prior to further flight for rework actions; inspections must be accomplished by specified intervals (e.g., 250 cycles in service or 500 since last inspection).
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Affected Aircraft
Pratt & Whitney JT9D-59A, -70A, -7Q, -7Q3 engines installed on Boeing 747, McDonnell Douglas DC-10, and Airbus A300 series aircraft.
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Source: Official FAA Source ↗
Retrieved: Apr 8, 2026
Rights: U.S. Government Public Domain
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