# AD 56-23-03: Horizontal Hinge Pin Assembly

- Type: Airworthiness directive
- Status: Current
- Products: Orlando Helicopter Airways HRS-1/CH-19, HRS-3/H-19B, S-55, S-55B and S-55C
- Superseded by: Nothing supersedes this AD
- Product type: Aircraft, Rotorcraft
- Registered aircraft: 17 may be affected, by airframe or engine model (OpenAirDocs)
- FAA DRS: https://drs.faa.gov/browse/excelExternalWindow/FE8FA8A356ACCFAF86256A4D00503166.0001
- DRS record last changed: May 30, 2024
- Page: https://openairdocs.org/ad/56-23-03

## The airworthiness directive

56-23-03 SIKORSKY: Applies to All Model S-55 Helicopters.

Compliance required as indicated.

Due to additional failures, it has been found necessary to lower the retirement time specified in AD 56-10-02. Accordingly, the horizontal hinge pin assembly, P/N S10-10-3331 and S10-10-3331-1 with 750 hours service must be replaced by December 1, 1956, or prior to the accumulation of 850 hours, whichever occurs first. Parts with 850 hours or more must be replaced prior to further service. Thereafter, P/N S10-10-3331 and S10-10-3331-1 are to be retired at not more than 750 hours.

This supersedes AD 56-10-02.

## Affected data sheets (2) (OpenAirDocs)

The type certificate data sheets whose models the AD names.

- [TCDS 1H4](https://openairdocs.org/tcds/1H4): Centerpointe Aerospace Inc.; names 3 of 3 models: S-55C, S-55, S-55B
- [TCDS HR1SO](https://openairdocs.org/tcds/HR1SO): Orlando Helicopter Airways Inc.; names 2 of 10 models: HRS-3/H-19B, HRS-1/CH-19

## 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: 17 (17 by airframe model, 0 by engine model)
- Makers: Sikorsky 15, Sikorsky/Orlando 1, Sikorsky/Vertical 1

Models with the most aircraft:

- [Sikorsky S-55B](https://openairdocs.org/model/sikorsky-s-55b): 9 aircraft (airframe model)
- [Sikorsky S-55](https://openairdocs.org/model/sikorsky-s-55): 3 aircraft (airframe model)
- [Sikorsky S55B](https://openairdocs.org/model/sikorsky-s55b): 3 aircraft (airframe model)
- [Sikorsky/Orlando S-55](https://openairdocs.org/model/sikorsky-orlando-s-55): 1 aircraft (airframe model)
- [Sikorsky/Vertical S-55](https://openairdocs.org/model/sikorsky-vertical-s-55): 1 aircraft (airframe model)

All 5 models: https://openairdocs.org/ad/56-23-03/models.md
Every aircraft: https://openairdocs.org/ad/56-23-03/aircraft.md

Its text cites no advisory circulars or STCs.

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