AD 89-23-12
Applicability
| Type | Manufacturer | Model | Details |
|---|---|---|---|
| engine | Rolls-Royce Corporation | 250-C28B | ALLISON GAS TURBINE DIVISION, GENERAL MOTORS CORPORATION Model 250-C28B and -C28C Engines |
| engine | Rolls-Royce Corporation | 250-C28C | ALLISON GAS TURBINE DIVISION, GENERAL MOTORS CORPORATION Model 250-C28B and -C28C Engines |
Unsafe Condition
Failure of the second stage turbine nozzle which can lead to rubbing contact between the nozzle diaphragm and the second stage turbine wheel possibly resulting in an uncontained turbine wheel failure.
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Required Actions
Modify and reidentify second stage turbine nozzle P/N 6898952 into P/N 23001942 in accordance with Allison Commercial Engine Alert Bulletin CEB-A-72-2044, Revision 4. Ferrying is allowed under FAR 21.197 and 21.199 to a base where the AD can be accomplished.
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Compliance Time
Within the next 100 hours time-in-service after the effective date of this AD, or at the next turbine repair or overhaul, whichever occurs first, but not later than November 30, 1989
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Affected Aircraft
Allison Model 250-C28B and -C28C engines with P/N 6898952 second stage turbine nozzle assembly, excluding specific turbine serial numbers listed in the AD.
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Source: Official FAA Source ↗
Retrieved: Apr 8, 2026
Rights: U.S. Government Public Domain
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