During a night flight, the pilot reported that after he landed on the runway, he slowed the airplane to taxi speed, and continued to the taxiway turnoff. The pilot misidentified the taxiway turn and turned off the runway into a grass area between the runway and taxiway. The pilot reported that the grass area had a downslope that led to level ground and he felt a bump from the tail as the airplane transitioned from the downslope to level ground. The airplane sustained substantial damage to the rudder.

The pilot reported no preimpact mechanical failures or malfunctions with the airframe or engine that would have precluded normal operation.