Airworthiness Directives; Hartzell Propeller Inc. Models HC-B3TN-2, HC-B3TN-3, HC-B3TN-5, HC-B3MN-3, HC-B4TN-3, HC-B4TN-5, HC-B4MN-5, HC-B4MP-3, HC-B4MP-5, and HC-B5MP-3 Propellers

The FAA is adopting a new airworthiness directive (AD) for Hartzell Propeller Inc. models HC-B3TN-2, HC-B3TN-3, HC-B3TN-5, HC- B3MN-3, HC-B4TN-3, HC-B4TN-5, HC-B4MN-5, HC-B4MP-3, HC-B4MP-5, and HC- B5MP-3 propellers, installed with propeller mounting bolts, part number (P/N) B-3339. This AD requires initial and repetitive visual inspections and torque checks of certain manufacture lot numbers of propeller mounting bolts, P/N B-3339, and eventual removal from service of those bolts. This AD results from the discovery during routine propeller installation that a bolt from a certain manufacture lot did not properly absorb the installation torque. This AD also results from the discovery that other bolts of the same part number from a different manufacture lot had material surface pitting. We are issuing this AD to prevent propeller attaching bolt failures or improperly secured propellers, which could lead to separation of the propeller from the airplane.