Date: 201305
Local time of day: 0001-0600
Location: ZZZ.Airport, US
Aircraft: Regional Jet 200 ER/LR (CRJ200)
Operator: Air Carrier
Operating under: Part 121
Flight phase: Parked
Aircraft component: Normal Brake System
Component problem: Failed
Reporter organization: Air Carrier
Reporter function: Other / Unknown
Reporter qualification: Maintenance Powerplant; Maintenance Airframe
Human factors: Human-Machine Interface; Situational Awareness
Second reporter function: Other / Unknown
Anomaly: Deviation / Discrepancy - Procedural Published Material / Policy; Ground Event / Encounter Loss Of Aircraft Control; Ground Event / Encounter Object
Detector: Person Maintenance
When detected: Taxi
Result: Aircraft Aircraft Damaged
Contributing factors: Human Factors; Procedure
Primary problem: Human Factors

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.


Second narrative: [The other Mechanic] and I were to taxi to a gate. [The other Mechanic] was in the Captain's seat and I was in the First Officer's seat. The tug pushed us out of the hangar and outside. The APU generator was just deferred before we pushed out of the hangar. We started the APU and then did a battery start on #1 Engine due to the APU generator being deferred. The tug was hooked up this whole time. Once the #1 Engine was started; the ground crew disconnected the tow bar from the [aircraft] and started to back away. Shortly thereafter; we slowly started to roll forward. [The other Mechanic] told me that the brakes weren't working. We both tried stepping on the brakes and setting the brakes with the brake handle but nothing worked. We then tried the #1 Reverser which didn't stop us either. [The other Mechanic] then shut #1 Engine down and we were able to use the rudder pedals to steer away from a plane parked on the ramp to the left and tried to get our plane aimed towards the grass ahead. Another plane was coming westbound under tow and we were able to maneuver to the right enough to avoid it and headed right towards the hangar door. We ran into the hangar door with the nose of the aircraft which finally stopped us. Luckily; nobody was hurt. There was a lack of communication between the taxi crew and the ground crew pushing the plane out of the hangar. Anytime abnormal start procedures are required; ground personnel should be required to wear headsets so that clear communication with the taxi crew will be available and utilized.


Synopsis: 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.