# AD 55-14-02: Hydraulic Cylinder Replacement

- Type: Airworthiness directive
- Status: Current
- Products: Piper PA-23
- Published: December 4, 1956
- Issued: December 4, 1956
- Superseded by: Nothing supersedes this AD
- Product type: Aircraft, Small airplane
- Registered aircraft: 155 may be affected, by airframe or engine model (OpenAirDocs)
- FAA DRS: https://drs.faa.gov/browse/excelExternalWindow/9A1B1AEC354CA0B38625698B0076497E.0001
- DRS record last changed: November 21, 2025
- Page: https://openairdocs.org/ad/55-14-02

## The airworthiness directive

55-14-02 PIPER: Applies to Model PA-23 Serial Numbers 23-1 to 23-208 Inclusive.

Compliance required by August 1, 1955.

Because of possible damage to the hydraulic actuating cylinders for the landing gear system and flap system of the two end plug retaining pins, as a result of excessive pressures caused by thermal expansion, it is necessary that these cylinders be inspected and replaced or modified as follows:

1. If the cylinder housing is upset or fractured, it must be replaced by a new reinforced cylinder P/N 455927.

(Piper Service Bulletin No. 138 dated May 9, 1955, covers this same subject.)

2. If the cylinder housing is not upset or fractured, it must either be replaced by P/N 455927, or reinforced by adding two retaining plugs in accordance with Piper Service Letter No. 250 dated June 8, 1955.

This supersedes AD 55-12-01.

## Affected data sheets (1) (OpenAirDocs)

The type certificate data sheets whose models the AD names.

- [TCDS 1A10](https://openairdocs.org/tcds/1A10): Piper Aircraft Inc.; names 1 of 6 models: PA-23

## 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: 155 (155 by airframe model, 0 by engine model)
- Makers: Piper 155

Models with the most aircraft:

- [Piper PA-23](https://openairdocs.org/model/piper-pa-23): 155 aircraft (airframe model)

All 1 models: https://openairdocs.org/ad/55-14-02/models.md
Every aircraft: https://openairdocs.org/ad/55-14-02/aircraft.md

Its text cites no advisory circulars or STCs.

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