Incident Overview
A pilot reported that during a climb to cruise altitude, the left engine began overheating. The pilot determined that the cowl plugs had been left in the engine's cowl opening. He shut down the engine and returned to the airport. During the instrument approach, the pilot attempted to extend the landing gear and flaps.
Go-Around and Collision
While on a 1-mile final approach, the tower advised the pilot to execute a go-around because the landing gear was not fully extended. The pilot stated that the airplane was past midfield before he applied power for the go-around. The airplane continued to descend and subsequently entered a stall/mush condition. The airplane collided with a taxiway and slid onto a grass area.
Post-Incident Inspection
On-scene investigation revealed no anomalies with the normal and emergency hydraulic systems. The CO2-operated emergency landing gear extension system was found to be capable of functioning but had not been used. The flaps were found in the full 'DOWN' position.