AD 90-24-01
Applicability
| Type | Manufacturer | Model | Details |
|---|---|---|---|
| engine | Honeywell International Inc. | ALF502R-3 | TEXTRON LYCOMING Models ALF502R Series Engines |
| engine | Honeywell International Inc. | ALF502R-3A | TEXTRON LYCOMING Models ALF502R Series Engines |
| engine | Honeywell International Inc. | ALF502R-4 | TEXTRON LYCOMING Models ALF502R Series Engines |
| engine | Honeywell International Inc. | ALF502R-5 | TEXTRON LYCOMING Models ALF502R Series Engines |
| engine | Honeywell International Inc. | ALF502R-6 | TEXTRON LYCOMING Models ALF502R Series Engines |
Unsafe Condition
Complete loss of engine power, uncontained disk failure, and possible damage to the aircraft.
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Required Actions
Inspect and recoat third stage high compressor (HC) disks with specified materials per SB ALF502R-72-203, Revision 2. Reinspect disks recoated with aluminum paint at intervals not exceeding 6,000, 1,500, or 1,000 cycles in service depending on the service bulletin. Remove modified second stage compressor spacer prior to specified cycle limits.
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Compliance Time
Within the next 500 cycles in service (CIS) not to exceed 8,500 cycles since new (CSN) for disks at or above 7,000 CSN on the effective date; at or prior to 7,500 CSN for those below 7,000 CSN on the effective date.
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Affected Aircraft
Textron Lycoming ALF502R series engines installed on, but not limited to British Aerospace BAE146 aircraft.
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Source: Official FAA Source ↗
Retrieved: Apr 8, 2026
Rights: U.S. Government Public Domain
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