# AD 51-28-02: Oil Pump Gears

- Type: Airworthiness directive
- Status: Current
- Products: Wytwornia Sprzetu Komunikacyjnego 6V4-178-B3, 6V4-178-B31, 6V4-178-B32, 6V4-178-B33, 6V4-200-C32 and 6V4-200-C33
- Superseded by: Nothing supersedes this AD
- Product type: Engine
- Registered aircraft: 84 may be affected, by airframe or engine model (OpenAirDocs)
- FAA DRS: https://drs.faa.gov/browse/excelExternalWindow/28657523621AE6B88625682B0062ADC3.0001
- DRS record last changed: May 30, 2024
- Page: https://openairdocs.org/ad/51-28-02

## The airworthiness directive

51-28-02 FRANKLIN: Applies to Model 6V4-178 Series Engines Prior to Serial Number 17690 and 6V4- 200 Series Engines Prior to Serial Number 26235. Compliance required as indicated. To preclude the possibility of oil pump failure, oil pump gears (P/N 10673 and 17736) must be inspected at each 300 hours of operation. Excessively galled gears must be replaced. If same part numbers are used for replacements, the 300-hour inspections will still apply. If carbonitrided oil pump drive gear, P/N 19377, and oil pump driven gear, P/N 19373, are installed, no further inspection is required. When these new carbonitrided gears are installed, suffix "P" must be stamped after the serial number of the engine on the nameplate - example: No. 1700P. (Franklin Service Bulletin No. 86, revised November 1, 1951, covers this same subject.) This supersedes AD's 51-22-02 and 51-11-03.

## Affected data sheets (1) (OpenAirDocs)

The type certificate data sheets whose models the AD names.

- [TCDS E-244](https://openairdocs.org/tcds/E-244): Franklin Sp. z.o.o.; names 6 of 12 models: 6V4-178-B33, 6V4-178-B31, 6V4-178-B3, 6V4-178-B32, 6V4-200-C32, 6V4-200-C33

## Registered aircraft it may apply to (OpenAirDocs)

Matched by airframe and engine model; the AD's applicability may narrow it by serial number, part number or equipment.

- Aircraft: 84 (0 by airframe model, 84 by engine model)
- Makers: Bell 48, Hiller 29, Continental Copters 2, Bell Kitz Kopters 1, Bell-Allied Helicopter 1, Bell-Continental Copters 1, Hiller - World Helicopters 1, Hiller-Heli-Cab 1

Models with the most aircraft:

- [Franklin 6V4 series](https://openairdocs.org/engine/franklin-6v4-series): 84 aircraft (engine model)

All 1 models: https://openairdocs.org/ad/51-28-02/models.md
Every aircraft: https://openairdocs.org/ad/51-28-02/aircraft.md

Its text cites no advisory circulars or STCs.

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