AD 64-28-01
Applicability
| Type | Manufacturer | Model | Details |
|---|---|---|---|
| aircraft | Hartzell Propeller, Inc. | HC-12X20-1 | HARTZELL Models HC-12X20-1, -2, -3, -5, and -7B Propellers |
| aircraft | Hartzell Propeller, Inc. | HC-12X20-2 | HARTZELL Models HC-12X20-1, -2, -3, -5, and -7B Propellers |
| aircraft | Hartzell Propeller, Inc. | HC-12X20-3 | HARTZELL Models HC-12X20-1, -2, -3, -5, and -7B Propellers |
| aircraft | Hartzell Propeller, Inc. | HC-12X20-5 | HARTZELL Models HC-12X20-1, -2, -3, -5, and -7B Propellers |
| aircraft | Hartzell Propeller, Inc. | HC-12X20-7 | HARTZELL Models HC-12X20-1, -2, -3, -5, and -7B Propellers |
Unsafe Condition
Failure of a hub spider can result in loss of propeller blade.
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Required Actions
Visually inspect hub spiders for cracks in accordance with Hartzell Service Bulletin No. 32 amended August 11, 1964, within 10 hours' time in service after AD effective date. Replace cracked parts before further flight. Replace hub spiders based on accumulated time in service: those with less than 400 hours must be replaced before 500 hours, and those with 400+ hours must be replaced within 100 hours after AD effective date.
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Compliance Time
Compliance required as indicated.
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Affected Aircraft
Hartzell Propeller, Inc. Models HC-12X20-1, -2, -3, -5, and -7B Propellers equipped with C-49-2B and C-49-2C Hub Spiders serial numbers 4220 through 5400 installed on Downer (Republic) RC-3; Navion, Navion A; and Grumman G-44 Series Aircraft.
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Source: Official FAA Source ↗
Retrieved: Apr 8, 2026
Rights: U.S. Government Public Domain
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