49-33-01 DOUGLAS: Applies to All Model DC-6 Airplanes Equipped With Hamilton Standard Model 43D60/6851A-O Props. \n\n\tCompliance required not later than September 10, 1949. \n\n\tAs a precautionary measure against fatigue failure, Hamilton Standard Model 43D60/6851A-O propeller blades may not be operated in excess of 3,500 hours unless the taper-bores have been remachined and reshotpeened by the manufacturer. In addition, any blades of this model which have sustained damage sufficient to change their face or edge alignment shall be withdrawn from service pending final results of manufacturer's test program.