AD 51-28-02
Applicability
| Type | Manufacturer | Model | Details |
|---|---|---|---|
| engine | Wytwornia Sprzetu Komunikacyjnego | 6V4-178-B3 | FRANKLIN Model 6V4-178 and 6V4- 200 Series Engines |
| engine | Wytwornia Sprzetu Komunikacyjnego | 6V4-178-B31 | FRANKLIN Model 6V4-178 and 6V4- 200 Series Engines |
| engine | Wytwornia Sprzetu Komunikacyjnego | 6V4-178-B32 | FRANKLIN Model 6V4-178 and 6V4- 200 Series Engines |
| engine | Wytwornia Sprzetu Komunikacyjnego | 6V4-178-B33 | FRANKLIN Model 6V4-178 and 6V4- 200 Series Engines |
| engine | Wytwornia Sprzetu Komunikacyjnego | 6V4-200-C32 | FRANKLIN Model 6V4-178 and 6V4- 200 Series Engines |
| engine | Wytwornia Sprzetu Komunikacyjnego | 6V4-200-C33 | FRANKLIN Model 6V4-178 and 6V4- 200 Series Engines |
Unsafe Condition
Oil pump gears (P/N 10673 and 17736) may experience excessive galling leading to failure.
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Required Actions
Inspect oil pump gears at each 300 hours of operation. Replace excessively galled gears. If replacing with same part numbers, continue 300-hour inspections. Install carbonitrided gears (P/N 19377 and 19373) to eliminate inspections, and stamp engine nameplate with suffix 'P'.
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Compliance Time
Compliance required as indicated.
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Affected Aircraft
FRANKLIN Model 6V4-178 Series Engines prior to serial number 17690 and 6V4-200 Series Engines prior to serial number 26235.
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Source: Official FAA Source ↗
Retrieved: Apr 8, 2026
Rights: U.S. Government Public Domain
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