The pilot reported that during the takeoff roll on a narrow runway about 70 to 80 knots, he noticed that the engines were not at full power. The pilot further reported that he advanced the throttles "a little further," but when he did so, the left main landing gear dropped off the left side of the runway into soft mud. Subsequently, the airplane veered off the runway to the left, the nose gear collapsed, and the airplane stopped in the mud.

The fuselage and engine firewalls sustained substantial damage.

The pilot did not report any preaccident mechanical malfunctions or failures with the airplane that would have precluded normal operation.