What was found
(CAN)DURING FLIGHT PILOTS REPORTED A HIGH FREQUENCY VIBRATION IN THE FOOT PEDALS AND PARKING BRAKE 'T' HANDLE. A LOUD GROWL NOISE WAS ALSO HEARD FROM THE #1 ENGINE. UPON SHUT DOWN AND FURTHER INVESTIGATION , IT WAS FOUND THAT THE #1 ENGINE OUTPUT FLANGE SHAFT HAD SHEARED AT THE POINT WHERE THE ATTACHMENT NUT AND COTTER PIN ARE LOCATED. THE OUTPUT FLANGE WAS REPLACED.