# AD 51-22-01: Gear Shaft Replacement

- Type: Airworthiness directive
- Status: Current
- Products: Sikorsky S-51
- Superseded by: Nothing supersedes this AD
- Product type: Aircraft, Rotorcraft
- FAA DRS: https://drs.faa.gov/browse/excelExternalWindow/5FB26E1D4C07616E86256A55006B6DC5.0001
- DRS record last changed: May 30, 2024
- Page: https://openairdocs.org/ad/51-22-01

## The airworthiness directive

51-22-01 SIKORSKY: Applies to All Model S-51 Helicopters.

Compliance required within the next 25 hours of operation, but not later than November 1, 1951.

Due to the reported failures of Gear Shaft (Generator Drive-Tail Drive Transmission System) P/N S-10-35-1004, all shafts in service shall be replaced by shafts which have been jig drilled (i.e., the taper pin hole is located squarely with respect to the splines) and which have been stoned and polished to deburr and remove any sharp radii where the taper pin hole intersects the splines.

(Sikorsky Service Information Circular No. 172, dated August 30, 1951, covers this same subject.)

## Affected data sheets (1) (OpenAirDocs)

The type certificate data sheets whose models the AD names.

- [TCDS H-2](https://openairdocs.org/tcds/H-2): Sikorsky Aircraft Corporation; names 1 of 1 models: S-51

## Registered aircraft it may apply to (OpenAirDocs)

No registered aircraft matched the models it names.

Its text cites no advisory circulars or STCs.

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