# AD 56-20-06: Gear Shafts

- Type: Airworthiness directive
- Status: Current
- Products: Curtiss-Wright/Marquette Double Row Turbo Cyclone 972TC18DA1 (R-3350-34, -91), Double Row Turbo Cyclone 972TC18DA2, Double Row Turbo Cyclone 972TC18DA3, Double Row Turbo Cyclone 972TC18DA4, Double Row Turbo Cyclone 981TC18EA1, Double Row Turbo Cyclone 988TC18EA1, Double Row Turbo Cyclone 988TC18EA2, Double Row Turbo Cyclone 988TC18EA3, Double Row Turbo Cyclone 988TC18EA4, Double Row Turbo Cyclone 988TC18EA5, Double Row Turbo Cyclone 988TC18EA6 and Governors
- Superseded by: Nothing supersedes this AD
- Product type: Appliance
- FAA DRS: https://drs.faa.gov/browse/excelExternalWindow/A43B3D10BD284E6A8625696F006B4202.0001
- DRS record last changed: May 30, 2024
- Page: https://openairdocs.org/ad/56-20-06

## The airworthiness directive

56-20-06 HAMILTON STANDARD: Applies to All Hamilton Standard Governors Installed on Wright TC18DA and TC18EA Series Turbocompound Engines.

Compliance required prior to October 15, 1956.

Subsequent to October 15, 1956, no Hamilton Standard governor drive gear shafts P/N 67035 shall be used in their governors installed on Wright TC18 Series turbocompound engines.

This supersedes AD 56-02-02.

## Affected data sheets (2) (OpenAirDocs)

The type certificate data sheets whose models the AD names.

- [TCDS E-287](https://openairdocs.org/tcds/E-287): Curtiss-Wright/Marquette Inc.; names 7 of 7 models: Double Row Turbo Cyclone 988TC18EA3, Double Row Turbo Cyclone 988TC18EA1, Double Row Turbo Cyclone 988TC18EA5, Double Row Turbo Cyclone 988TC18EA6, Double Row Turbo Cyclone 988TC18EA2, Double Row Turbo Cyclone 988TC18EA4, Double Row Turbo Cyclone 981TC18EA1
- [TCDS E-272](https://openairdocs.org/tcds/E-272): Curtiss-Wright/Marquette Inc.; names 4 of 4 models: Double Row Turbo Cyclone 972TC18DA4, Double Row Turbo Cyclone 972TC18DA3, Double Row Turbo Cyclone 972TC18DA1 (R-3350-34; -91), Double Row Turbo Cyclone 972TC18DA2

## 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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