AD 58-20-04
Applicability
| Type | Manufacturer | Model | Details |
|---|---|---|---|
| aircraft | Boeing Defense & Space Group | 42A | Airworthiness Directives; VERTOL Models 42 Series and 44 Series Helicopters |
| aircraft | Boeing Defense & Space Group | 42B | Airworthiness Directives; VERTOL Models 42 Series and 44 Series Helicopters |
| aircraft | Boeing Defense & Space Group | 44A | Airworthiness Directives; VERTOL Models 42 Series and 44 Series Helicopters |
| aircraft | Boeing Defense & Space Group | 44B | Airworthiness Directives; VERTOL Models 42 Series and 44 Series Helicopters |
Unsafe Condition
Fatigue failures of the 22D1073-4 jaw clutch driven and 22D1137-4 jaw clutch driver coupling can preclude successful reengagement of the clutch, thereby disconnecting the rotor drive system from the engine.
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Required Actions
Replace the 22D1073-4 driven and 22D1137-4 driver couplings with new 42D1142-1 and 42D1143-1 couplings respectively. Replace spring (22D1170-1 with 63D2363-1) and cam (3D3143 with 04D1043-1). Ream existing holes and drill/ream additional holes in yoke and follower, install 42D1008-2 pins and AN 381-3-10 cotter pins. Destroy or permanently mark removed couplings.
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Compliance Time
as soon as possible but not later than December 1, 1958
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Affected Aircraft
Boeing Defense & Space Group Models 42A, 42B, 44A, 44B helicopters
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Federal Register Abstract
Clutch Coupling Replacement
Applicability Source Text
Show captured applicability text from the source AD
AD Final Rules - DRS_58-20-04.html Copy URL Print/Save as PDF Document Versions Feedback Details AD Number: 58-20-04 Document Type: AD Final Rules Docket Number: Unknown Subject Heading: Airworthiness Directives; VERTOL Models 42 Series and 44 Series Helicopters Subject: Clutch Coupling Replacement Status: Current Citation: This information is not available. Citation Publish Date: Effective Date: Make: Boeing Defense & Space Group Model: 42A | 42B | 44A | 44B Product Type: Aircraft Product Subtype: Rotorcraft Affected AD: Superseded AD: Affected By: Superseded By: Service/Office: Office of Primary Responsibility: CFR Part Reference: Part 39 Comments: AIRWORTHINESS DIRECTIVES FINAL RULES: 58-20-04 CITATION: This information is not available. PAGE NUMBER: DOCKET NUMBER: Unknown AMENDMENT: AD NUMBER: 58-20-04 SUBJECT HEADING: Airworthiness Directives; VERTOL Models 42 Series and 44 Series Helicopters ACTION: SUMMARY: DATES: ADDRESSES: FOR FURTHER INFORMATION CONTACT: SUPPLEMENTARY INFORMATION: REGULATORY TEXT: 58-20-04 VERTOL: Applies to All Models 42 Series and 44 Series Helicopters. Compliance required as soon as possible but not later than December 1, 1958. Fatigue failures of the 22D1073-4 jaw clutch driven and 22D1137-4 jaw clutch driver coupling have been found on both military and commercial Models 42 and 44 Series helicopters. Failure of the teeth of these couplings can preclude successful reengagement of the clutch, thereby disconnecting the rotor drive system from the engine. To prevent failures of this nature, both the aforementioned driver and driven couplings must be replaced by the new 42D1142-1 and 42D1143-1 driver and driven couplings respectively. The replacement couplings are of a new twelve-tooth design and as such, require the replacement of the following additional parts and rework to account for differences in jaw teeth height and travel: .... Parts to be replaced New replacement part Spring 22D1170-1 63D2363-1 Cam 3D3143 04D1043-1 Ream two existing holes 0.3750/0.3755-inch diameter thru 42D1046-1 yoke and 42D1048-1 follower. Install 42D1008-2 pin and AN 381-3-10 cotter pin. Drill and ream 0.3750/0.3755-inch diameter, two additional places, on 1.5 centerline thru 42D1046-1 yoke and 42D1048-1 follower. Install 42D1008-2 pins when yoke diameter is 1.00 inch. Install AN 381-3-10 cotter pins. All couplings removed should be destroyed or permanently marked in a manner that will assure retirement from service. (Vertol's S.D.T.M.-1866 covers this same subject.) This supersedes AD 58-10-04. FOOTER:
Document Text
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AD Final Rules - DRS_58-20-04.html Copy URL Print/Save as PDF Document Versions Feedback Details AD Number: 58-20-04 Document Type: AD Final Rules Docket Number: Unknown Subject Heading: Airworthiness Directives; VERTOL Models 42 Series and 44 Series Helicopters Subject: Clutch Coupling Replacement Status: Current Citation: This information is not available. Citation Publish Date: Effective Date: Make: Boeing Defense & Space Group Model: 42A | 42B | 44A | 44B Product Type: Aircraft Product Subtype: Rotorcraft Affected AD: Superseded AD: Affected By: Superseded By: Service/Office: Office of Primary Responsibility: CFR Part Reference: Part 39 Comments: AIRWORTHINESS DIRECTIVES FINAL RULES: 58-20-04 CITATION: This information is not available. PAGE NUMBER: DOCKET NUMBER: Unknown AMENDMENT: AD NUMBER: 58-20-04 SUBJECT HEADING: Airworthiness Directives; VERTOL Models 42 Series and 44 Series Helicopters ACTION: SUMMARY: DATES: ADDRESSES: FOR FURTHER INFORMATION CONTACT: SUPPLEMENTARY INFORMATION: REGULATORY TEXT: 58-20-04 VERTOL: Applies to All Models 42 Series and 44 Series Helicopters. Compliance required as soon as possible but not later than December 1, 1958. Fatigue failures of the 22D1073-4 jaw clutch driven and 22D1137-4 jaw clutch driver coupling have been found on both military and commercial Models 42 and 44 Series helicopters. Failure of the teeth of these couplings can preclude successful reengagement of the clutch, thereby disconnecting the rotor drive system from the engine. To prevent failures of this nature, both the aforementioned driver and driven couplings must be replaced by the new 42D1142-1 and 42D1143-1 driver and driven couplings respectively. The replacement couplings are of a new twelve-tooth design and as such, require the replacement of the following additional parts and rework to account for differences in jaw teeth height and travel: .... Parts to be replaced New replacement part Spring 22D1170-1 63D2363-1 Cam 3D3143 04D1043-1 Ream two existing holes 0.3750/0.3755-inch diameter thru 42D1046-1 yoke and 42D1048-1 follower. Install 42D1008-2 pin and AN 381-3-10 cotter pin. Drill and ream 0.3750/0.3755-inch diameter, two additional places, on 1.5 centerline thru 42D1046-1 yoke and 42D1048-1 follower. Install 42D1008-2 pins when yoke diameter is 1.00 inch. Install AN 381-3-10 cotter pins. All couplings removed should be destroyed or permanently marked in a manner that will assure retirement from service. (Vertol's S.D.T.M.-1866 covers this same subject.) This supersedes AD 58-10-04. FOOTER:
Source: Official FAA Source ↗
Retrieved: Apr 8, 2026
Rights: U.S. Government Public Domain
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