AD 70-04-04
Applicability
| Type | Manufacturer | Model | Details |
|---|---|---|---|
| engine | Honeywell International Inc. | TPE331-1 | AIRESEARCH Model TPE-331-1 and TPE-331-2 Engines |
| engine | Honeywell International Inc. | TPE331-1U | AIRESEARCH Model TPE-331-1 and TPE-331-2 Engines |
| engine | Honeywell International Inc. | TPE331-1UA | AIRESEARCH Model TPE-331-1 and TPE-331-2 Engines |
| engine | Honeywell International Inc. | TPE331-2 | AIRESEARCH Model TPE-331-1 and TPE-331-2 Engines |
| engine | Honeywell International Inc. | TPE331-2U | AIRESEARCH Model TPE-331-1 and TPE-331-2 Engines |
| engine | Honeywell International Inc. | TPE331-2UA | AIRESEARCH Model TPE-331-1 and TPE-331-2 Engines |
Unsafe Condition
Backing off of the high speed pinion retaining nut can cause a serious engine failure.
AI-generated summary from the source AD text. Verify against the official source before acting.
Required Actions
Within 10 hours time in service, inspect the engine oil filter for metal particles and install a placard advising pilots to shut down the engine if there is an abrupt loss of torque indication. At each inspection, replace the filter and return the removed filter for laboratory examination. Within 150 hours time in service, rework or replace the high speed pinion gear shaft assembly per AiResearch Service Bulletin 587.
AI-generated summary from the source AD text. Verify against the official source before acting.
Compliance Time
Within 10 hours time in service
AI-generated summary from the source AD text. Verify against the official source before acting.
Affected Aircraft
Honeywell International Inc. Model TPE331-1 and -2 engines with serial numbers: 90005, 90009, 90010, 90011, 90014, 90016, 90017, 90018, 90019, 90022, 90023, 90024, 90027, 90028, 90029, 90030, 91003, 91004, 91005, 91006, 91009, 91011, 91013 thru 91021, 91023, 91024, 91025, 91027, 92001, 92002, 92003, 92004, 92005, 92007, 92010, 92012, 92013, 92014, 92016 thru 92027, 93007, 93008, 93009, 93010.
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
This site is not affiliated with or endorsed by the FAA. Always verify with official sources.