AD 57-06-04
Applicability
| Type | Manufacturer | Model | Details |
|---|---|---|---|
| engine | Curtiss-Wright/Marquette, Inc. | Double Row Cyclone 956C18CA1 | WRIGHT Models C18CA, C18CB, TC18DA, and TC18EA Series Engines |
| engine | Curtiss-Wright/Marquette, Inc. | Double Row Cyclone 975C18CB1 | WRIGHT Models C18CA, C18CB, TC18DA, and TC18EA Series Engines |
| engine | Curtiss-Wright/Marquette, Inc. | Double Row Turbo Cyclone 972TC18DA1 (R-3350-34, -91) | WRIGHT Models C18CA, C18CB, TC18DA, and TC18EA Series Engines |
| engine | Curtiss-Wright/Marquette, Inc. | Double Row Turbo Cyclone 972TC18DA2 | WRIGHT Models C18CA, C18CB, TC18DA, and TC18EA Series Engines |
| engine | Curtiss-Wright/Marquette, Inc. | Double Row Turbo Cyclone 972TC18DA3 | WRIGHT Models C18CA, C18CB, TC18DA, and TC18EA Series Engines |
| engine | Curtiss-Wright/Marquette, Inc. | Double Row Turbo Cyclone 972TC18DA4 | WRIGHT Models C18CA, C18CB, TC18DA, and TC18EA Series Engines |
| engine | Curtiss-Wright/Marquette, Inc. | Double Row Turbo Cyclone 981TC18EA1 | WRIGHT Models C18CA, C18CB, TC18DA, and TC18EA Series Engines |
| engine | Curtiss-Wright/Marquette, Inc. | Double Row Turbo Cyclone 988TC18EA1 | WRIGHT Models C18CA, C18CB, TC18DA, and TC18EA Series Engines |
| engine | Curtiss-Wright/Marquette, Inc. | Double Row Turbo Cyclone 988TC18EA2 | WRIGHT Models C18CA, C18CB, TC18DA, and TC18EA Series Engines |
| engine | Curtiss-Wright/Marquette, Inc. | Double Row Turbo Cyclone 988TC18EA3 | WRIGHT Models C18CA, C18CB, TC18DA, and TC18EA Series Engines |
Unsafe Condition
The engine front section bearing durability may be insufficient due to improper assembly of the propeller shaft thrust bearing (ball bearing) and radial bearing (roller bearing).
AI-generated summary from the source AD text. Verify against the official source before acting.
Required Actions
At next engine overhaul, assemble the engine front section with the propeller shaft thrust bearing (ball bearing) behind the radial bearing (roller bearing) as viewed from the propeller end. Inspect propeller shaft thrust and radial bearings for proper internal clearances if overhauled after April 15, 1957, per Wright Aeronautical Division Service Letter dated March 22, 1957. Balance propellers according to propeller manufacturer's recommendations.
AI-generated summary from the source AD text. Verify against the official source before acting.
Compliance Time
Compliance required as indicated.
AI-generated summary from the source AD text. Verify against the official source before acting.
Affected Aircraft
Curtiss-Wright/Marquette, Inc. models Double Row Cyclone 956C18CA1, Double Row Cyclone 975C18CB1, Double Row Turbo Cyclone 972TC18DA1, and TC18EA series engines.
AI-generated summary from the source AD text. Verify against the official source before acting.
Source: Official FAA Source ↗
Retrieved: Apr 8, 2026
Rights: U.S. Government Public Domain
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