What was found
ACFT WAS IN FOR A 100-HOUR INSP. MECHANIC PERFORMING TAIL ROTOR GEARBOX MOUNT RE-TORQUE, CUT THE SAFETY WIRE AND THE BOLT PULLED OUT. IT WAS ALSO FOUND THAT 2 OTHER BOLTS WERE ONLY IN PLACE BY 2 THREADS. MECHANIC STATED BOLTS WERE INCORRECT, PN NAS1304-24H, AND THERE WAS A WASHER UNDER THE HEAD OF EACH OF THE 4 BOLTS. RECORDS REVEALED THE TAIL BOOM HAD BEEN REPLACED WITH AN ALTERNATE TAIL BOOM, PN 369A3500-619. PARTS MANUAL INDICATES MODEL TAIL BOOM, BOLT, PN NAS1304-26H (ITEM 38) WAS TO BE INSTALLED AND NO WASHERS UNDER THE HEAD OF THE BOLT. MM ONLY MENTIONS NAS1304-24H BOLT FOR INSTALLATION AND DEPICTS A WASHER UNDER THE BOLT HEAD IN THE ILLUSTRATION.