AD 56-20-06
final rule
Applicability
| Type | Manufacturer | Model | Details |
|---|---|---|---|
| aircraft | Curtiss-Wright/Marquette, Inc. | Hamilton Standard | Double Row Turbo Cyclone 972TC18DA1 (R-3350-34, -91) | HAMILTON STANDARD Governors Installed on Wright TC18DA and TC18EA Series Turbocompound Engines |
| aircraft | Curtiss-Wright/Marquette, Inc. | Hamilton Standard | Double Row Turbo Cyclone 972TC18DA2 | HAMILTON STANDARD Governors Installed on Wright TC18DA and TC18EA Series Turbocompound Engines |
| aircraft | Curtiss-Wright/Marquette, Inc. | Hamilton Standard | Double Row Turbo Cyclone 972TC18DA3 | HAMILTON STANDARD Governors Installed on Wright TC18DA and TC18EA Series Turbocompound Engines |
| aircraft | Curtiss-Wright/Marquette, Inc. | Hamilton Standard | Double Row Turbo Cyclone 972TC18DA4 | HAMILTON STANDARD Governors Installed on Wright TC18DA and TC18EA Series Turbocompound Engines |
| aircraft | Curtiss-Wright/Marquette, Inc. | Hamilton Standard | Double Row Turbo Cyclone 981TC18EA1 | HAMILTON STANDARD Governors Installed on Wright TC18DA and TC18EA Series Turbocompound Engines |
| aircraft | Curtiss-Wright/Marquette, Inc. | Hamilton Standard | Double Row Turbo Cyclone 988TC18EA1 | HAMILTON STANDARD Governors Installed on Wright TC18DA and TC18EA Series Turbocompound Engines |
| aircraft | Curtiss-Wright/Marquette, Inc. | Hamilton Standard | Double Row Turbo Cyclone 988TC18EA2 | HAMILTON STANDARD Governors Installed on Wright TC18DA and TC18EA Series Turbocompound Engines |
| aircraft | Curtiss-Wright/Marquette, Inc. | Hamilton Standard | Double Row Turbo Cyclone 988TC18EA3 | HAMILTON STANDARD Governors Installed on Wright TC18DA and TC18EA Series Turbocompound Engines |
| aircraft | Curtiss-Wright/Marquette, Inc. | Hamilton Standard | Double Row Turbo Cyclone 988TC18EA4 | HAMILTON STANDARD Governors Installed on Wright TC18DA and TC18EA Series Turbocompound Engines |
| aircraft | Curtiss-Wright/Marquette, Inc. | Hamilton Standard | Double Row Turbo Cyclone 988TC18EA5 | HAMILTON STANDARD Governors Installed on Wright TC18DA and TC18EA Series Turbocompound Engines |
| appliance | Curtiss-Wright/Marquette, Inc. | Hamilton Standard | Double Row Turbo Cyclone 972TC18DA1 (R-3350-34, -91) | HAMILTON STANDARD Governors Installed on Wright TC18DA and TC18EA Series Turbocompound Engines |
| appliance | Curtiss-Wright/Marquette, Inc. | Hamilton Standard | Double Row Turbo Cyclone 972TC18DA2 | HAMILTON STANDARD Governors Installed on Wright TC18DA and TC18EA Series Turbocompound Engines |
| appliance | Curtiss-Wright/Marquette, Inc. | Hamilton Standard | Double Row Turbo Cyclone 972TC18DA3 | HAMILTON STANDARD Governors Installed on Wright TC18DA and TC18EA Series Turbocompound Engines |
| appliance | Curtiss-Wright/Marquette, Inc. | Hamilton Standard | Double Row Turbo Cyclone 972TC18DA4 | HAMILTON STANDARD Governors Installed on Wright TC18DA and TC18EA Series Turbocompound Engines |
| appliance | Curtiss-Wright/Marquette, Inc. | Hamilton Standard | Double Row Turbo Cyclone 981TC18EA1 | HAMILTON STANDARD Governors Installed on Wright TC18DA and TC18EA Series Turbocompound Engines |
| appliance | Curtiss-Wright/Marquette, Inc. | Hamilton Standard | Double Row Turbo Cyclone 988TC18EA1 | HAMILTON STANDARD Governors Installed on Wright TC18DA and TC18EA Series Turbocompound Engines |
| appliance | Curtiss-Wright/Marquette, Inc. | Hamilton Standard | Double Row Turbo Cyclone 988TC18EA2 | HAMILTON STANDARD Governors Installed on Wright TC18DA and TC18EA Series Turbocompound Engines |
| appliance | Curtiss-Wright/Marquette, Inc. | Hamilton Standard | Double Row Turbo Cyclone 988TC18EA3 | HAMILTON STANDARD Governors Installed on Wright TC18DA and TC18EA Series Turbocompound Engines |
| appliance | Curtiss-Wright/Marquette, Inc. | Hamilton Standard | Double Row Turbo Cyclone 988TC18EA4 | HAMILTON STANDARD Governors Installed on Wright TC18DA and TC18EA Series Turbocompound Engines |
| appliance | Curtiss-Wright/Marquette, Inc. | Hamilton Standard | Double Row Turbo Cyclone 988TC18EA5 | HAMILTON STANDARD Governors Installed on Wright TC18DA and TC18EA Series Turbocompound Engines |
| appliance | Curtiss-Wright/Marquette, Inc. | Hamilton Standard | Double Row Turbo Cyclone 988TC18EA6 | HAMILTON STANDARD Governors Installed on Wright TC18DA and TC18EA Series Turbocompound Engines |
| appliance | Curtiss-Wright/Marquette, Inc. | Hamilton Standard | Governors | HAMILTON STANDARD Governors Installed on Wright TC18DA and TC18EA Series Turbocompound Engines |
Unsafe Condition
Gear shafts P/N 67035 in Hamilton Standard governors may fail, leading to loss of engine governor control.
AI-generated summary from the source AD text. Verify against the official source before acting.
Required Actions
Replace governor drive gear shafts P/N 67035 with approved serviceable units. Compliance required prior to October 15, 1956.
AI-generated summary from the source AD text. Verify against the official source before acting.
Compliance Time
prior to October 15, 1956
AI-generated summary from the source AD text. Verify against the official source before acting.
Affected Aircraft
Hamilton Standard governors installed on Wright TC18DA and TC18EA series turbocompound engines.
AI-generated summary from the source AD text. Verify against the official source before acting.
Federal Register Abstract
Gear Shafts
Applicability Source Text
Show captured applicability text from the source AD
AD Final Rules - DRS_56-20-06.html Copy URL Print/Save as PDF Document Versions Feedback Details AD Number: 56-20-06 Document Type: AD Final Rules Docket Number: Unknown Subject Heading: HAMILTON STANDARD Governors Installed on Wright TC18DA and TC18EA Series Turbocompound Engines Subject: Gear Shafts Status: Current Citation: This information is not available. Citation Publish Date: Effective Date: Make: Curtiss-Wright/Marquette, Inc. | Hamilton Standard Model: Double Row Turbo Cyclone 972TC18DA1 (R-3350-34, -91) | Double Row Turbo Cyclone 972TC18DA2 | Double ...Show more Product Type: Appliance 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: 56-20-06 CITATION: This information is not available. PAGE NUMBER: DOCKET NUMBER: Unknown AMENDMENT: AD NUMBER: 56-20-06 SUBJECT HEADING: HAMILTON STANDARD Governors Installed on Wright TC18DA and TC18EA Series Turbocompound Engines ACTION: SUMMARY: DATES: ADDRESSES: FOR FURTHER INFORMATION CONTACT: SUPPLEMENTARY INFORMATION: REGULATORY TEXT: 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. FOOTER:
Document Text
Show stored source text (verify against official source)
AD Final Rules - DRS_56-20-06.html Copy URL Print/Save as PDF Document Versions Feedback Details AD Number: 56-20-06 Document Type: AD Final Rules Docket Number: Unknown Subject Heading: HAMILTON STANDARD Governors Installed on Wright TC18DA and TC18EA Series Turbocompound Engines Subject: Gear Shafts Status: Current Citation: This information is not available. Citation Publish Date: Effective Date: Make: Curtiss-Wright/Marquette, Inc. | Hamilton Standard Model: Double Row Turbo Cyclone 972TC18DA1 (R-3350-34, -91) | Double Row Turbo Cyclone 972TC18DA2 | Double ...Show more Product Type: Appliance 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: 56-20-06 CITATION: This information is not available. PAGE NUMBER: DOCKET NUMBER: Unknown AMENDMENT: AD NUMBER: 56-20-06 SUBJECT HEADING: HAMILTON STANDARD Governors Installed on Wright TC18DA and TC18EA Series Turbocompound Engines ACTION: SUMMARY: DATES: ADDRESSES: FOR FURTHER INFORMATION CONTACT: SUPPLEMENTARY INFORMATION: REGULATORY TEXT: 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. FOOTER:
Source: Official FAA Source ↗
Retrieved: Apr 8, 2026
Rights: U.S. Government Public Domain
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