AD 57-08-02
Applicability
| Type | Manufacturer | Model | Details |
|---|---|---|---|
| aircraft | Scotts-Bell 47 Inc | 47B3 | Airworthiness Directives; Bell Model 47B3, 47D, 47D1, 47G, and 47H1 Helicopters |
| aircraft | Scotts-Bell 47 Inc | 47D | Airworthiness Directives; Bell Model 47B3, 47D, 47D1, 47G, and 47H1 Helicopters |
| aircraft | Scotts-Bell 47 Inc | 47D1 | Airworthiness Directives; Bell Model 47B3, 47D, 47D1, 47G, and 47H1 Helicopters |
| aircraft | Scotts-Bell 47 Inc | 47G | Airworthiness Directives; Bell Model 47B3, 47D, 47D1, 47G, and 47H1 Helicopters |
| aircraft | Scotts-Bell 47 Inc | 47H-1 | Airworthiness Directives; Bell Model 47B3, 47D, 47D1, 47G, and 47H1 Helicopters |
Unsafe Condition
Failures of the hinge in the oil system Parker check valve (P/N 1111-517703, 1111-517704, or 1111-517744) have occurred, resulting in restriction of oil flow from the pump.
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Required Actions
Inspect the Parker check valve at next oil change and every 25 hours thereafter for hinge wear/failure and freedom of operation. Replace the valve if defects are found. The 25-hour inspections may be discontinued after installing the approved James Pond Clark check valve (P/N 879A-10TT).
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Compliance Time
At next oil change and every 25 hours thereafter until replacement is accomplished.
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Affected Aircraft
Bell Model 47B3, 47D, 47D1, 47G, and 47H1 helicopters equipped with Parker Check Valves in the oil system.
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Source: Official FAA Source ↗
Retrieved: Apr 8, 2026
Rights: U.S. Government Public Domain
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