Cessna 340 pilot reported loss of aircraft control during takeoff after the aircraft had undergone annual inspection. The pilot returned to the departure airport and found the rudder trim was at full left stops.

Narrative

My aircraft was just undergoing an annual. I always take more time with the preflight after maintenance for all the obvious reasons; not knowing what has been changed. Everything appeared normal and after being cleared to depart straight out and to wait for a crosswind call; I taxied for takeoff. I noticed that the plane was a little left of the center line with plenty of right rudder. On takeoff the plane made an uncontrolled left turn toward some hangers. I was able to climb above the buildings and over a hill that is parallel to the run way while in a constant left turn with full right aileron. I notified the tower that I [needed priority] due to unable to control the aircraft. At this point I had made a 180 degree turn and had gained about 1;000 feet. I reduced power from climb to 60% and RPM from 2;700 to 2;300 RPM. With the reduced thrust i was able to extend my downwind and turn to left base and final by using less than full opposite aileron. I landed on the runway in a strong slip. This flight took a total of 5 minutes. On examination after shut down I found that the rudder was at the left stops. I had never seen it so far to one side that did not notice it. From now on I am going to touch all the trim controls so I confirm their position. This was totally my fault for not centering it prior to departure.