Baron 58/58TC
Flight Crew Commercial
Training / Qualification; Confusion
Aircraft Equipment Problem Critical; Inflight Event / Encounter Loss Of Aircraft Control
Flight Crew Overcame Equipment Problem; Flight Crew Returned To Clearance; Flight Crew Regained Aircraft Control
Human Factors; Aircraft
I left [before sun rise] and was flying for about an hour when I had a runaway trim. The auto pilot was out in the airplane and deferred per the MEL and I was therefore having to hand fly the airplane. I was using mainly manual trim throughout the flight fine tuning the airplane. I decided to use the electric trim and I noticed that it was sticking and so I stopped using it. I reached over to get something off of the seat next to me and I looked back and noticed I was in a dive. The electric trim was running down and the nose dropped. I tried to disconnect the trim with the red disconnect button but it didn't work. I then searched for the circuit breaker. In the time it took for me to find the breaker and try to continue to fly I lost 700 feet and turned just over 90 degrees. I immediately climbed back up and turned back on course. ATC asked me 'So are you heading back to ZZZ?' I told them no and said that I had a trim problem and I thought it was the attitude indicator too but I thought about it and it was just the trim and me turning while looking down in the airplane. I suggest that I keep my eyes outside if it is VMC like it was therefore I wouldn't have turned as much. Also if I had known exactly where the circuit breaker was for the trim then it wouldn't have taken as long to get it offline.
BE58 pilot cruising at 9;000 FT reports runaway trim; resulting in a 700 foot altitude loss and a 90 degree turn before the electric trim circuit breaker can be located and pulled. The autopilot was not being used at the time.