AD 66-14-03
Applicability
| Type | Manufacturer | Model | Details |
|---|---|---|---|
| engine | Lycoming Engines | O-540-B2B5 | LYCOMING Model O-540-B2B5 Engines |
Unsafe Condition
Failure of crankshaft idler shafts, specifically part number 70390, in Lycoming Model O-540-B2B5 engines.
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Required Actions
Replace crankshaft idler shaft P/N 70390 with P/N 73014 and accessory housing P/N 71648 with P/N 75367 or 71648-85. Compliance must be done before specific time-in-service thresholds based on engine usage.
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Compliance Time
Compliance required before accumulation of 400 hours' time in service since overhaul or new, or within next 100 hours' time in service depending on engine's time-in-service on the effective date.
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Affected Aircraft
Lycoming Model O-540-B2B5 engines, serial numbers 101-40 through 8267-40, installed in Piper PA-25 and Intermountain Manufacturing Company airplanes, except engines remanufactured at Lycoming after November 14, 1965.
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Source: Official FAA Source ↗
Retrieved: Apr 8, 2026
Rights: U.S. Government Public Domain
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