AD 64-20-01
Applicability
| Type | Manufacturer | Model | Details |
|---|---|---|---|
| aircraft | Hartzell Propeller, Inc. | HC-C2Y | HARTZELL Models HC-C2YK-1/7666-2 and HC-E2YL-2B/7663-4 Propellers |
| aircraft | Hartzell Propeller, Inc. | HC-E2Y | HARTZELL Models HC-C2YK-1/7666-2 and HC-E2YL-2B/7663-4 Propellers |
Unsafe Condition
Failure of the plastic pitch change blocks in Hartzell HC-E2YL-2B and HC-C2YK-1 propellers resulted in severe roughness or vibration in flight.
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Required Actions
Inspect propeller blades for pitch change movement and replace plastic pitch change blocks as necessary per Hartzell Service Bulletin No. 86 revised June 17, 1964, within 10 hours' time in service after this AD's effective date. If not yet done, inspections must occur within every subsequent 10 hours' time in service from the last inspection until the modification in SB No. 86 is accomplished, after which repetitive inspections may stop.
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Compliance Time
within 10 hours' time in service after the effective date of this AD unless already accomplished within the last 10 hours' time in service, and thereafter within every 10 hours' time in service from the last inspection
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Affected Aircraft
Hartzell Propeller, Inc. Models HC-C2YK-1/7666-2 Serial Numbers AW-1 to AW-603 and HC-E2YL-2B/7663-4 Propellers Serial Numbers BG-1 to BG-777
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Source: Official FAA Source ↗
Retrieved: Apr 8, 2026
Rights: U.S. Government Public Domain
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