Airworthiness Directives; Hartzell Propeller Inc. Model HC-B5MP-3( )/M10282A( )+6 and HC-B5MP-3( )/M10876( )( )( )( ) Five-Bladed Propellers.

The FAA is superseding an existing airworthiness directive (AD) for Hartzell Propeller Inc. model HC-B5MP-3( )/M10282A( )+6 five- bladed propellers. That AD currently requires initial and repetitive torque check inspections on the mounting bolts on certain model Hartzell Propeller Inc. HC-B5MP-3( )/M10282A( )+6 five-bladed propellers, replacement of mounting bolts if necessary, and inspection and resurfacing of the engine and propeller mounting flanges if necessary. This AD requires the same actions but requires more detailed overhaul inspections and maintenance than the previous AD, AD 2004-21- 01. This AD also adds Hartzell Propeller Inc. HC-B5MP-3( )/M10876( )( )( )( ) five-bladed propellers to the applicability. This AD results from reports of fretting wear still occurring between the engine and propeller mounting flanges. The fretting wear results in loss of mounting bolt preload, causing failure of the mounting bolts. We are issuing this AD to prevent propeller separation from the airplane.