Airworthiness Directives; Hartzell Propeller Inc. ( )HC-( )2Y( )-( ) Propellers

This amendment supersedes priority letter AD 90-02-23, that is applicable to certain Hartzell Propeller Inc. ( )HC-( )2Y( )-( ) propellers. That priority letter currently requires repetitive visual inspections of propeller hubs for cracks using a 10X glass and, if necessary, removal of cracked hubs and replacement with serviceable parts. This amendment changes the frequency and method of inspection by requiring initial and repetitive eddy current inspections (ECI) of the propeller hub fillet radius for cracks and requires that certain model propeller hubs be removed from service. In addition, this AD allows installation of an improved design propeller hub as terminating action to the repetitive ECI. This amendment is prompted by reports of cracked propeller hubs found in service after they had been inspected in accordance with the visual inspections required by the current AD. The actions specified in this AD are intended to prevent failure of the propeller hub resulting from cracks, that can cause blade separation and subsequent loss of aircraft control.