What was found
(CAN) DEPARTED (IFR) & SHORTLY AFTER TAKEOFF, PILOT REPORTED AN "ELEVATOR PROBLEM" & DECLARED AN EMERGENCY. ADVISED CENTRE RETURNING TO AIRPORT. ARFF CALLED OUT TO BE ON STANDBY AS THE ACFT ARRIVED SAFELY. APPROXIMATELY 1 HR LATER, SAME ACFT WAS TAKING OFF & PILOT REJECTED TAKEOFF, CITING AN EQUIPMENT PROBLEM & TAXIED BACK TO HANGAR. ORIGINALLY THOUGHT TO BE AN AUTOPILOT PROBLEM, CREW RETURNED TO AIRPORT, TESTED AUTOPILOT & ATTEMPTED A SECOND TAKEOFF WITH SAME RESULT. MX FOUND TRIM POSITION TRANSMITTER WINDING & WIPER TO HAVE FAILED CAUSING ERRONEOUS INDICATION IN COCKPIT. TAKEOFF ATTEMPTED WITH WHAT WAS THOUGHT TO BE A CORRECT TRIM SETTING WHEN IN FACT TRIM SETTING DID NOT MATCH ACTUAL TRIM POSITION. TRANSMITTER APPEARED TO BE ORIGINAL EQUIPEMENT. MX REPLACED TRANSMITTER & TESTED THE TRIM SYSTEM. (TC 20091023003)