# AD 48-18-02: Bevel Drive Gear Splines

- 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- Superseded by: Nothing supersedes this AD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/73AC7A75304F85F486256A55006B629E.0001
- DRS record last changed: May 30, 2024
- Page: https://openairdocs.org/ad/48-18-02

## The airworthiness directive

48-18-02 SIKORSKY: Applies to Model S-51 Series Helicopters Serial Numbers SS-51- 01 Through SS-5157.

Compliance required at first main gearbox overhaul but in any event not later than the next 400 hours of operation.

To prevent cracks caused by stress concentration at the corners of the internal splines on the bevel drive gear (Sikorsky P/N S-535360), a 1/32-inch radius relief should be formed at the lower end of each spline. The procedure for accomplishing this modification is given in Sikorsky Aircraft Information Circular No. 40 and No. 40 Revision "A".

## 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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