Incident Overview
On a ramp area, the captain of a Dornier 228 (registration N259MC) was completing the checklist during passenger loading while the first officer secured the door and moved forward. The captain then started the #2 engine and began a single-engine taxi, intending to make a right turn to stay clear of a parked Dornier 228 (registration N264MC). As N259MC began rolling forward, the captain noted that the nosewheel steering (NWS) was inoperative. He applied normal braking but received no response, and the aircraft began a left turn. The captain switched the hydraulic pump from the 'NORMAL' to the 'MAN ON' (manual) position; however, before hydraulic pressure could be built up by battery power, N259MC collided with N264MC.
Investigation Findings
An investigation revealed that the #2 generator was not connected to the generator bus. No part malfunction or failure was found during checks of the aircraft systems. The nosewheel steering and normal brakes were electro-hydraulically actuated. Without generator power, the hydraulic system, nosewheel steering, and normal brakes would not have been operating with the hydraulic switch in the 'NORMAL' position. An emergency (parking) brake was available, but it was not used.
Training and Documentation Gaps
The training program, operations manual, and Dornier 228-series pilot operating handbook did not address single-engine ground operations or the effects of an interruption in generator power.
Conclusion
The collision occurred due to the loss of nosewheel steering and normal braking capability during single-engine taxi, resulting from the #2 generator not being connected to the generator bus. The absence of specific guidance on single-engine ground operations and generator power interruption in training and documentation was noted.