AD 54-25-02
Applicability
| Type | Manufacturer | Model | Details |
|---|---|---|---|
| engine | Curtiss-Wright/Marquette, Inc. | Double Row Cyclone 975C18CB1 | WRIGHT Models 975C18CB1, 972TC18DA1, and 972TC18DA2 Engines |
| engine | Curtiss-Wright/Marquette, Inc. | Double Row Turbo Cyclone 972TC18DA1 (R-3350-34, -91) | WRIGHT Models 975C18CB1, 972TC18DA1, and 972TC18DA2 Engines |
| engine | Curtiss-Wright/Marquette, Inc. | Double Row Turbo Cyclone 972TC18DA2 | WRIGHT Models 975C18CB1, 972TC18DA1, and 972TC18DA2 Engines |
Unsafe Condition
Front intermediate cam drive gear failures and associated possible engine overspeeding.
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Required Actions
Remove specified intermediate cam drive gears (P/N's 138608, 138608 N, 171385, 171238, or 171387) from the front cam drive gear train. Use gears with increased tooth width and thick hubs (P/N's 171347, 171348, or 171994) in the front configuration. Follow assembly instructions in TC18DA Overhaul Manual sections V.17 and VIII.2, recording measurements on engine build-up sheets.
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Compliance Time
November 1, 1955 and at next and each subsequent overhaul.
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Affected Aircraft
Curtiss-Wright/Marquette, Inc. Models 975C18CB1, 972TC18DA1, and 972TC18DA2 engines.
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Federal Register Abstract
Cam Drive Gear
Applicability Source Text
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AD Final Rules - DRS_54-25-02.html Copy URL Print/Save as PDF Document Versions Feedback Details AD Number: 54-25-02 Document Type: AD Final Rules Docket Number: Unknown Subject Heading: WRIGHT Models 975C18CB1, 972TC18DA1, and 972TC18DA2 Engines Subject: Cam Drive Gear Status: Current Citation: This information is not available. Citation Publish Date: Effective Date: Make: Curtiss-Wright/Marquette, Inc. Model: Double Row Cyclone 975C18CB1 | Double Row Turbo Cyclone 972TC18DA1 (R-3350-34, -91) | Double Row Tur...Show more Product Type: Engine Product Subtype: Affected AD: Superseded AD: Affected By: Superseded By: Service/Office: Office of Primary Responsibility: CFR Part Reference: Part 39 Comments: AIRWORTHINESS DIRECTIVES FINAL RULES: 54-25-02 CITATION: This information is not available. PAGE NUMBER: DOCKET NUMBER: Unknown AMENDMENT: AD NUMBER: 54-25-02 SUBJECT HEADING: WRIGHT Models 975C18CB1, 972TC18DA1, and 972TC18DA2 Engines ACTION: SUMMARY: DATES: ADDRESSES: FOR FURTHER INFORMATION CONTACT: SUPPLEMENTARY INFORMATION: REGULATORY TEXT: 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.) FOOTER:
Document Text
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AD Final Rules - DRS_54-25-02.html Copy URL Print/Save as PDF Document Versions Feedback Details AD Number: 54-25-02 Document Type: AD Final Rules Docket Number: Unknown Subject Heading: WRIGHT Models 975C18CB1, 972TC18DA1, and 972TC18DA2 Engines Subject: Cam Drive Gear Status: Current Citation: This information is not available. Citation Publish Date: Effective Date: Make: Curtiss-Wright/Marquette, Inc. Model: Double Row Cyclone 975C18CB1 | Double Row Turbo Cyclone 972TC18DA1 (R-3350-34, -91) | Double Row Tur...Show more Product Type: Engine Product Subtype: Affected AD: Superseded AD: Affected By: Superseded By: Service/Office: Office of Primary Responsibility: CFR Part Reference: Part 39 Comments: AIRWORTHINESS DIRECTIVES FINAL RULES: 54-25-02 CITATION: This information is not available. PAGE NUMBER: DOCKET NUMBER: Unknown AMENDMENT: AD NUMBER: 54-25-02 SUBJECT HEADING: WRIGHT Models 975C18CB1, 972TC18DA1, and 972TC18DA2 Engines ACTION: SUMMARY: DATES: ADDRESSES: FOR FURTHER INFORMATION CONTACT: SUPPLEMENTARY INFORMATION: REGULATORY TEXT: 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.) FOOTER:
Source: Official FAA Source ↗
Retrieved: Apr 8, 2026
Rights: U.S. Government Public Domain
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Related Airworthiness Directives
57-06-04
final ruleWRIGHT Models C18CA, C18CB, TC18DA, and TC18EA Series Engines
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