AD 59-09-04
Applicability
| Type | Manufacturer | Model | Details |
|---|---|---|---|
| aircraft | Boeing Defense & Space Group | 44A | Airworthiness Directives; VERTOL Models 44A, B, and C Helicopters |
| aircraft | Boeing Defense & Space Group | 44B | Airworthiness Directives; VERTOL Models 44A, B, and C Helicopters |
Unsafe Condition
Failure of the low velocity fan disc assembly, P/N 42P6422, due to cracks originating at the blade retaining bolt hole in the disc flange forward face, progressing radially and circumferentially, leading to separation of the disc portion with fan blades and fuselage damage.
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Required Actions
Retire fan disc assemblies P/N 42P6422 at 400 hours' time. Alternatively, by 400 hours' time, remove spinner P/N 42P6420, inspect disc flange for cracks, reassemble with AN 960-416 washers, conduct inspections every four flight-hours, and retire/mutilate if cracks found.
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Compliance Time
no later than May 15, 1959
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Affected Aircraft
Boeing Defense & Space Group Models 44A, B, and C Helicopters
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Source: Official FAA Source ↗
Retrieved: Apr 8, 2026
Rights: U.S. Government Public Domain
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