Narrative:

I was to taxi a CRJ200 from the hangar to the gate. Due to the fact that the APU generator was just deferred by maintenance; we needed to do a battery start to get the aircraft engines started. Prior to moving the aircraft; I discussed with the tow team that without the generator we would not have electrical power to run the hydraulic pumps; thus we would not have brake pressure. The tow team was aware that they would need to keep the aircraft hooked up to the tug or choked until we had brake pressure available. Another mechanic (first officer's seat) and I (pilot seat) boarded the aircraft in the hangar and were onboard while the aircraft was being pushed outside. After being pushed outside; we started the APU and proceeded to start the #1 engine. Once the #1 engine was running; I turned on the #1 generator. At about the same time the tug driver signaled that he was disconnecting external power. Since external power was not connected to the aircraft; I was confused as to why he would be signaling that. The next thing I noticed was that the tug was backing up and we were starting to follow. At this time; we had not established hydraulic power for brakes and steering. As we continued to move forward; we were trying to control the aircraft by applying the brakes (hoping for accumulator pressure) and engaging the thrust reverser. We continued gaining speed; and with no control decided to shut down the #1 engine. We somehow turned sharply to the right and were heading toward the hangar doors. The aircraft ran into the doors and came to a stop. This event occurred due to a miscommunication/lack of communication between the aircraft taxi mechanics and the tow team. We; the taxi mechanics; were not ready for the tow team to disconnect us from the tug. During engine starts under abnormal conditions; there should be verbal communications (headset) between the flight deck and ground crew.

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Original NASA ASRS Text

Title: Maintenance Technicians are assigned to taxi a CRJ200 from the hangar to a gate with the APU generator inoperative. After engine start the ground crew disconnects the tug before hydraulic pressure can be established resulting in no brakes and uncontrolled aircraft movement. The engine is shut down but the aircraft continues to roll and comes into contact with the hangar door.

Narrative: I was to taxi a CRJ200 from the hangar to the gate. Due to the fact that the APU Generator was just deferred by Maintenance; we needed to do a battery start to get the aircraft engines started. Prior to moving the aircraft; I discussed with the tow team that without the generator we would not have electrical power to run the hydraulic pumps; thus we would not have brake pressure. The tow team was aware that they would need to keep the aircraft hooked up to the tug or choked until we had brake pressure available. Another Mechanic (First Officer's seat) and I (pilot seat) boarded the aircraft in the hangar and were onboard while the aircraft was being pushed outside. After being pushed outside; we started the APU and proceeded to start the #1 Engine. Once the #1 Engine was running; I turned on the #1 Generator. At about the same time the tug driver signaled that he was disconnecting external power. Since external power was not connected to the aircraft; I was confused as to why he would be signaling that. The next thing I noticed was that the tug was backing up and we were starting to follow. At this time; we had not established hydraulic power for brakes and steering. As we continued to move forward; we were trying to control the aircraft by applying the brakes (hoping for accumulator pressure) and engaging the thrust reverser. We continued gaining speed; and with no control decided to shut down the #1 Engine. We somehow turned sharply to the right and were heading toward the hangar doors. The aircraft ran into the doors and came to a stop. This event occurred due to a miscommunication/lack of communication between the aircraft taxi mechanics and the tow team. We; the taxi mechanics; were not ready for the tow team to disconnect us from the tug. During engine starts under abnormal conditions; there should be verbal communications (headset) between the flight deck and ground crew.

Data retrieved from NASA's ASRS site as of July 2013 and automatically converted to unabbreviated mixed upper/lowercase text. This report is for informational purposes with no guarantee of accuracy. See NASA's ASRS site for official report.