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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Source: Official FAA Source ↗
Retrieved: Apr 8, 2026
Rights: U.S. Government Public Domain
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