AD 70-05-06
Applicability
| Type | Manufacturer | Model | Details |
|---|---|---|---|
| aircraft | Hartzell Propeller, Inc. | HC-B3T | HARTZELL PROPELLERS Models HC-B3TN-5C Series Propellers |
Unsafe Condition
Cracks in the inner surface of the pilot tube hole and scratches, gouges, or tool marks in the area of minimum wall thickness of Hartzell T10176( ) and T10176H( ) type blades installed on HC-B3TN-5C series propellers.
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Required Actions
Inspect blades by removing them from the propeller and the smaller needle bearing, clean and inspect the pilot tube hole for cracks using dye penetrant, visually inspect for scratches, gouges, or tool marks, and check wall thickness per Hartzell Bulletin No. 95. Replace blades with cracks, defects, or insufficient wall thickness before further flight.
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Compliance Time
Within the next 50 hours after the effective date (March 11, 1970) for propellers with 700+ hours, or prior to 750 hours in service for those with less than 700 hours. Reinspect every 1500 hours in service from the last inspection.
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Affected Aircraft
Hartzell Propeller, Inc. HC-B3TN-5C series propellers with T10176( ) or T10176H( ) type blades used on AiResearch TPE331-( ) engines.
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Source: Official FAA Source ↗
Retrieved: Apr 8, 2026
Rights: U.S. Government Public Domain
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