We're looking into it.
The RV-8 accident NTSB Probable Cause Report involving a pitch change knob failure was brought to our attention two weeks after the report was released. Hartzell did not participate in the investigation so we are looking into the facts and circumstances that went into the report conclusions. Hartzell will examine the accident propeller soon and confer with the NTSB metallurgical lab about their conclusions. At the present time Hartzell has no concerns with shot peened pitch change knobs on approved engine/propeller combinations operating within the limitations defined for the applicable engine configuration. “Approved” engine/propeller combinations include type certified combinations or Experimental Amateur Built applications specifically approved by Hartzell correspondence. If you have questions regarding propeller operating limitations for your specific engine/propeller combination, please contact Hartzell Propeller Product Support. You will be asked for your engine configuration including compression ratio, ignition systems, modified camshafts, crankshaft, pistons, induction, turbo/superchargers, exhaust, injections systems such as alcohol or nitrous oxide, or any other modification that would alter the power and torsional vibration characteristics.
Air Safety Investigator - Hartzell Propeller