Incident Overview
A twin-engine turboprop airplane sustained substantial damage when it struck the side of a terminal building while parking on the airport terminal's ramp. The pilot reported that the landing and taxi to the ramp were normal. While taxiing, the pilot used the Beta range (reverse pitch on the propellers) to control speed.
Sequence of Events
After stopping on the ramp, the pilot engaged the Beta range to back the airplane approximately four to six feet to align with another parked aircraft. The pilot then set the parking brake and moved the throttles to flight idle, bringing the propeller levers to the feather position. As the propellers were being feathered, the airplane began to taxi forward. The pilot responded by moving the propeller levers full forward and returning the throttles to Beta. Despite these inputs, the aircraft continued rolling forward. The pilot then moved the fuel mixture handles to the fuel shut off position. The airplane struck the plate glass-sided building at an estimated speed of 3 to 4 mph.
Post-Incident Reports
The pilot reported that both the brakes and the Beta range were functioning properly before and during the event. The airport manager stated that the runways and ramp surfaces had thin patches of loose snow, but the braking action was considered good.
Investigation
No probable cause has been stated in the source material. The investigation focused on the pilot's actions and the operational status of the aircraft's systems.