- Models
- Double Row Cyclone 975C18CB1, Double Row Turbo Cyclone 972TC18DA1 (R-3350-34, -91), Double Row Turbo Cyclone 972TC18DA2
- Product
- Engine
Unofficial copy of the text in the FAA’s Dynamic Regulatory System. The FAA’s own copy is the authoritative one. DRS record last changed May 30, 2024.
Copies of the files this page was built from, with their SHA-256. Retrieved October 18, 2026.
| File | Size | SHA-256 | Original |
|---|---|---|---|
| FAA DRS HTML | 21 KB | b972d80f…8ed4569 | FAA DRS (API key needed) |
On this page
The airworthiness directive
54-25-02 WRIGHT: Applies to All Models 975C18CB1, 972TC18DA1, and 972TC18DA2 Engines.
Compliance required as indicated.
I. Compliance required by November 1, 1955.
To alleviate front intermediate cam drive gear failures and associated possible engine overspeeding, the following intermediate cam drive gears must be removed from the front cam drive gear train: P/N's 138608, 138608 N, 171385, 171238, or 171387.
These gears may still be used in the rear cam drive configuration. Intermediate cam drive gears incorporating increased tooth width and thick hubs must be used in the front cam drive configuration. The following gears comply with this requirement: P/N's 171347, 171348, or 171994.
II. Compliance required at next and each subsequent overhaul.
To insure proper assembly of cam drive gear configurations, the following assembly instructions must be followed and applicable measurements recorded on engine build up sheets:
TC18DA Overhaul Manual:Section V. Instruction 17.
Section VIII. Instruction No. 2 plus referenced Table of Limits fits including Reference No. 238. (Wright Aeronautical Division Service Bulletins Numbers C18C-83 and TC18-92 cover these same subjects.)
Affected TCDS · 2
The type certificate data sheets for the models this AD names, matched by model and maker.