# AD 56-08-01: Pitch Limit Switches

- Type: Airworthiness directive
- Status: Current
- Products: Curtiss-Wright C632S, C634D and C634S
- Superseded by: Nothing supersedes this AD
- Product type: Propeller
- FAA DRS: https://drs.faa.gov/browse/excelExternalWindow/923BEABE09E6C8588625696C006F62CB.0001
- DRS record last changed: May 30, 2024
- Page: https://openairdocs.org/ad/56-08-01

## The airworthiness directive

56-08-01 CURTISS: Applies to All Models C632S, C634D and C634S Propellers.

Compliance required as indicated.

I. Replace low pitch limit switches P/N 110425 at not more than the following intervals:

Douglas DC-6 Series Aircraft 3,500 Hours

Lockheed 749 Series Aircraft 3,500 Hours

Lockheed 1049 Series Aircraft 3,500 Hours

Convair 240 Series Aircraft 1,000 Hours

(Curtiss Service Bulletin No. 52 dated December 29, 1949, and appropriate service manuals also cover these recommendations.)

II. Disassemble and visually inspect low pitch limit switches P/N 154592 at not more than the same intervals. Inspect for proper switch operation and for mechanical and electrical condition. Failure or malfunction other than normal service wear shall be cause for replacement of switch parts or of the assembly. Switches not revealing adverse conditions may be returned to service.

This supersedes Section III of AD 53-05-01.

## Affected data sheets (3) (OpenAirDocs)

The type certificate data sheets whose models the AD names.

- [TCDS P-825](https://openairdocs.org/tcds/P-825): Curtiss-Wright Corporation; names 1 of 1 models: C634S
- [TCDS P-847](https://openairdocs.org/tcds/P-847): Curtiss-Wright Corporation; names 1 of 1 models: C632S
- [TCDS P-883](https://openairdocs.org/tcds/P-883): Curtiss-Wright Corporation; names 1 of 1 models: C634D

## Registered aircraft it may apply to (OpenAirDocs)

No registered aircraft matched the models it names.

Its text cites no advisory circulars or STCs.

---
OpenAirDocs.org is an independent research project of [Contrail Labs](https://contraillabs.com/). It is not affiliated with the FAA or the NTSB. Source documents are U.S. government works in the public domain.