# AD 51-12-01: Piston Pins

- Type: Airworthiness directive
- Status: Current
- Products: Wright Aeronautical Division, Curtiss-Wright 718C9GB1, Military Cyclone R-1820 Series, Cyclone 702C9GC1, Cyclone 702C9GC2, Cyclone 702C9GC3, Cyclone 702C9GC4, Cyclone 702C9GC5, Cyclone 702C9GC6, Cyclone 704C9GC1, Cyclone 704C9GC2, Cyclone 704C9GC3, Cyclone 704C9GC4 and 20 more
- Superseded by: Nothing supersedes this AD
- Product type: Engine
- FAA DRS: https://drs.faa.gov/browse/excelExternalWindow/6F99BBA42354A2E48625682D00558C12.0001
- DRS record last changed: May 30, 2024
- Page: https://openairdocs.org/ad/51-12-01

## The airworthiness directive

51-12-01 WRIGHT: Applies to All Models C9GB, C9GC, C9HD and Military R-1820 Series Engines.

Compliance required as soon as possible, but not later than April 1, 1952.

To preclude piston pin failures, piston pins P/N's 68827, 117691, and 131061, which have not been carburized, must be replaced at each engine overhaul. Piston pins P/N's 117691 and 131061 retain the same part number when carburized, but may be identified by the symbol "C" on the recessed end of the pin. Piston pins P/N 68827 were never carburized and therefore should not be reused. It is suggested that orders for carburized piston pins be placed well in advance of required delivery date.

(Wright Service Bulletin No. C9-156A covers this same subject.)

## Affected data sheets (4) (OpenAirDocs)

The type certificate data sheets whose models the AD names.

- [TCDS E-219](https://openairdocs.org/tcds/E-219): Curtiss-Wright/Marquette Inc.; names 17 of 30 models: Cyclone 728C9GC1, Cyclone 702C9GC5, Cyclone 728C9GC2, Cyclone 702C9GC2, Cyclone 704C9GC1, Cyclone 704C9GC5, Cyclone 704C9GC3, Cyclone 702C9GC4…
- [TCDS E-243](https://openairdocs.org/tcds/E-243): Curtiss-Wright/Marquette Inc.; names 13 of 14 models: Cyclone 737C9HD1, Cyclone 740C9HD2, Cyclone 737C9HD4, Cyclone 736C9HD2, Cyclone 736C9HD3, Cyclone 736C9HD1, Cyclone 737C9HD2, Cyclone 977C9HD2…
- [TCDS TC 192](https://openairdocs.org/tcds/TC%20192): Wright Aeronautical Division Curtiss-Wright Corporation; names 1 of 3 models: 718C9GB1
- [TCDS TC 5E-10](https://openairdocs.org/tcds/TC%205E-10): Wright Aeronautical Division Curtiss-Wright Corporation; names 1 of 1 models: Military Cyclone R-1820 Series

## 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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