Incident Sequence
The right engine was started as passengers completed boarding. After the copilot secured the cabin door and took his seat, the pilot released the parking brake and control lock, then applied power to taxi. When a turn was commanded, the nosewheel steering did not respond. The pilot applied normal and emergency braking, but neither had any effect on the aircraft's movement. The pilot then ordered the right engine to be shut down. The aircraft continued to roll across the ramp until it collided with a parked aircraft.
Operator's Previous Experience
The operator had experienced similar failures during the six months prior to this incident. Despite efforts to duplicate and isolate the problems, all attempts were unsuccessful.
Post-Incident Repairs
During post-incident repairs, numerous landing gear system components were replaced. After these replacements, the problem did not surface again.
Investigation Outcome
No reason for the original failures was determined.