Airworthiness Directives; Hamilton Standard Model 14RF-9 Propellers

This amendment adopts a new airworthiness directive (AD) that is applicable to Hamilton Standard Model 14RF-9 propellers. This action supersedes priority letter AD 95-24-09 that currently requires a one- time ultrasonic shear wave inspection of the propeller blade shank for cracks or surface indications. This action continues to require an ultrasonic shear wave inspection, but adds a one-time visual and fluorescent penetrant inspection and repair of the propeller blade shank for mechanical damage. This amendment is prompted by propeller blade shank visual inspection results on blades that were removed from service as a result of the one-time ultrasonic shear wave inspections. The inspection results showed that minor damage could exist that is not detected by the ultrasonic shear wave inspection. This amendment is also prompted by the development of a method to remove the fiberglass on the blade shank permitting shank inspection and repair procedures. The actions specified by this AD are intended to prevent propeller blade separation due to propeller blade shank cracking, which could result in loss of control of the aircraft.