NTSB Publishes Recommendations On Hartzell Props

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The NTSB has issued a recommendation letter on certain Hartzell propellers. In its letter, the agency advises the FAA to require the immediate inspection of all propeller parts and propeller assemblies overhauled or inspected by T&W Propellers in Chino, Calif., to determine if they are airworthy. The notice also advises the FAA to require that all Hartzell Z-shank propellers be overhauled every 2,000 hours or five years, whichever comes first, as recommended by the manufacturer. The NTSB's letter stems from an accident investigation, which involved a Beech 95 (Travelair) that crashed shortly after takeoff on Jan. 24, 2003. The investigation revealed that a two-and-a-half-foot section of the Hartzell propeller blade separated from the assembly on the aircraft's number-two (right) engine. Metallurgy analysis determined the separation occurred due to fatigue cracking that initiated at corrosion pits on the internal surface of the blade's pilot-tube hole. Although the maintenance records show the propellers to have been overhauled per manufacturer's specifications, the NTSB felt incorrect procedures were carried out. T&W Propellers surrendered its Air Agency Certificate on Feb. 14, 2003, in a response to a letter of investigation from the FAA.