AD 78-25-08 R3
Applicability
| Type | Manufacturer | Model | Details |
|---|---|---|---|
| engine | Honeywell International Inc. | TPE331-1 | AIRESEARCH MANUFACTURING COMPANY OF ARIZONA Model TSE331-3 and TPE331-1, -2, -3, -5, -6 Series Engines |
| engine | Honeywell International Inc. | TPE331-1U | AIRESEARCH MANUFACTURING COMPANY OF ARIZONA Model TSE331-3 and TPE331-1, -2, -3, -5, -6 Series Engines |
| engine | Honeywell International Inc. | TPE331-1UA | AIRESEARCH MANUFACTURING COMPANY OF ARIZONA Model TSE331-3 and TPE331-1, -2, -3, -5, -6 Series Engines |
| engine | Honeywell International Inc. | TPE331-2 | AIRESEARCH MANUFACTURING COMPANY OF ARIZONA Model TSE331-3 and TPE331-1, -2, -3, -5, -6 Series Engines |
| engine | Honeywell International Inc. | TPE331-2U | AIRESEARCH MANUFACTURING COMPANY OF ARIZONA Model TSE331-3 and TPE331-1, -2, -3, -5, -6 Series Engines |
| engine | Honeywell International Inc. | TPE331-2UA | AIRESEARCH MANUFACTURING COMPANY OF ARIZONA Model TSE331-3 and TPE331-1, -2, -3, -5, -6 Series Engines |
| engine | Honeywell International Inc. | TPE331-3 | AIRESEARCH MANUFACTURING COMPANY OF ARIZONA Model TSE331-3 and TPE331-1, -2, -3, -5, -6 Series Engines |
| engine | Honeywell International Inc. | TPE331-3U | AIRESEARCH MANUFACTURING COMPANY OF ARIZONA Model TSE331-3 and TPE331-1, -2, -3, -5, -6 Series Engines |
| engine | Honeywell International Inc. | TPE331-3UW | AIRESEARCH MANUFACTURING COMPANY OF ARIZONA Model TSE331-3 and TPE331-1, -2, -3, -5, -6 Series Engines |
| engine | Honeywell International Inc. | TPE331-3W | AIRESEARCH MANUFACTURING COMPANY OF ARIZONA Model TSE331-3 and TPE331-1, -2, -3, -5, -6 Series Engines |
Unsafe Condition
Destructive overspeed of the turbine rotor in the event of any one of several single engine failures in the main reduction gear drive.
AI-generated summary from the source AD text. Verify against the official source before acting.
Required Actions
Incorporate the modified engine fuel control drive gear train in the main reduction gear box per AiResearch Service Bulletin TPE331-72-0061, revision 1 or 2. Torque sensor assembly P/N 3101726-2 may replace P/N 3101726-1 as per Service Bulletin TPE331-72-0232, Revision 1.
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Compliance Time
Within the next 3100 hours' time in service after July 1, 1979, or at the next overhaul after July 1, 1979, or prior to December 31, 1985, whichever comes first.
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Affected Aircraft
AiResearch Model TSE331-3U and TPE331-1, -2, -3U, -3UW, -5, and -6 series engines.
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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