# AD 57-06-04: Engine Front Section

- Type: Airworthiness directive
- Status: Current
- Products: Curtiss-Wright/Marquette Double Row Cyclone 956C18CA1, Double Row Cyclone 975C18CB1, 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 and 1 more
- Superseded by: Nothing supersedes this AD
- Product type: Engine
- FAA DRS: https://drs.faa.gov/browse/excelExternalWindow/2DD8743439192FEE8625685F0057C16E.0001
- DRS record last changed: May 30, 2024
- Page: https://openairdocs.org/ad/57-06-04

## The airworthiness directive

57-06-04 WRIGHT: Applies to All Aircraft Incorporating C18CA, C18CB, TC18DA, and TC18EA Series Engines.

Compliance required as indicated.

Results of recent investigations indicate that the engine front section bearing durability can be improved by accomplishing the following:

1. At next engine overhaul the engine front section must be assembled with the propeller shaft thrust bearing (ball bearing) behind the radial bearing (roller bearing) as viewed from the propeller end of the engine.

(Wright Aeronautical Division Service Bulletins Nos. C18C-252, TC18D-255, and TC-18E-66 cover this same subject.)

Propellers must be balanced in accordance with instructions contained in applicable propeller manufacturer's recommendations.

2. Engines overhauled after April 15, 1957, must incorporate engine propeller shaft thrust bearings (ball bearings) and radial bearings (roller bearings) that have been inspected for proper internal bearing clearances in accordance with instructions issued by the Wright Aeronautical Division in their Service Letter dated March 22, 1957.

## Affected data sheets (3) (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
- [TCDS E-270](https://openairdocs.org/tcds/E-270): Curtiss-Wright/Marquette Inc.; names 2 of 2 models: Double Row Cyclone 975C18CB1, Double Row Cyclone 956C18CA1

## 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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