AD 93-08-16
Applicability
| Type | Manufacturer | Model | Details |
|---|---|---|---|
| engine | Pratt & Whitney Division | PW4050 | PRATT & WHITNEY Models PW4050, PW4052, PW4056, PW4060, and PW4060A Engines |
| engine | Pratt & Whitney Division | PW4052 | PRATT & WHITNEY Models PW4050, PW4052, PW4056, PW4060, and PW4060A Engines |
| engine | Pratt & Whitney Division | PW4056 | PRATT & WHITNEY Models PW4050, PW4052, PW4056, PW4060, and PW4060A Engines |
| engine | Pratt & Whitney Division | PW4060 | PRATT & WHITNEY Models PW4050, PW4052, PW4056, PW4060, and PW4060A Engines |
| engine | Pratt & Whitney Division | PW4060A | PRATT & WHITNEY Models PW4050, PW4052, PW4056, PW4060, and PW4060A Engines |
Unsafe Condition
High pressure compressor (HPC) failure caused by excessive blade tip to airseal interference, which can result in total loss of engine thrust.
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Required Actions
Incorporate Boeing ASB 747-73A2055 to limit low pressure rotor speed to Approach Idle rpm on PW4000 powered Boeing 747-400 aircraft. Incorporate Boeing ASB 767-73A0033 to limit low pressure rotor speed to Approach Idle rpm on PW4000 powered Boeing 767-200/-300 aircraft. Alternative methods of compliance may be approved by the Manager, Engine Certification Office.
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Compliance Time
within 30 calendar days after the effective date of this airworthiness directive (July 12, 1993), unless accomplished previously
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Affected Aircraft
Pratt & Whitney PW4050, PW4052, PW4056, PW4060, and PW4060A engines equipped with EEC Part Numbers 50D437, 50D821, 50D823, 51D011, and 51D012, installed on Boeing 747 and 767 aircraft.
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Source: Official FAA Source ↗
Retrieved: Apr 8, 2026
Rights: U.S. Government Public Domain
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