Narrative:

After a thorough preflight/cockpit setup we waited for passengers to arrive. Once they arrived I loaded the bags and was the last person on the airplane. I was catching up with them as the captain settled into the cockpit. The captain began starting engines. As I sat down in the right seat we monitored the starting of the second engine and I put my seatbelt and headset on. We then checked for a new ATIS and ran the after start/before taxi checklist. I called ground and we were cleared for taxi. The captain applied thrust to get the airplane moving and commented about how the throttles were different from the C550 (he had been flying a C550 during the previous few days). We needed to make a right turn to exit the ramp. As the captain applied right rudder and right brake to steer the airplane he said 'the brakes aren't working.' I tried the brakes on my side; which also did not work. We were rapidly approaching other parked airplanes. He reached for the emergency brake handle but mistakenly pulled the emergency gear release handle and continued pulling on the handle while looking forward at the airplanes we were approaching. I noticed he had grabbed the wrong handle and I quickly reached to pull the correct handle. I was stopped short by my shoulder harnesses on my first attempt. I sat back and got my shoulders free and reached again and pulled the handle. The pneumatic brakes stopped the airplane but our left wing struck the left flap of another airplane on the ramp. We shut down engines. Once stopped we tried to determine why the brakes hadn't worked. The annunciator panel said low brk press and anti skid inoperative. I looked over at the circuit breaker panel on the captain's side and noticed that the power brakes breaker had tripped. I pushed the breaker back in; the hydraulic pump charged the accumulator and I set the parking brake.cessna has issued a service letter addressing the brake system in the C56X. The letter cautions pilots and maintenance personnel against using the power brakes circuit breaker as a switch. People pull the breaker to keep the pump from running every couple of minutes and this can cause the breaker to become weak and fail. The letter advises/reminds that without power to the braking system the pilot must use the pneumatic system to stop the airplane. I know pilots and maintenance personnel who have used the breaker in the manner cessna says not to. It is my belief that the breaker was weak and failed after releasing the parking brake and during the first seconds of the taxi. I know for certain that the breaker was in when we set up the cockpit before passengers arrived. I don't know for certain when it tripped. I am going to give the captain the benefit of the doubt and trust that the breaker was in as he started engines and that he tested the brakes when after releasing the parking brake and before applying throttle. In that scenario; the breaker failed at the absolute worst possible time given our speed and proximity to other aircraft. I believe one contributing factor to this incident is the excess thrust used to get the aircraft rolling. This; I believe; was due to the captain flying a C550 one day and a C56X the next day and not thinking about the much greater performance/response with the C56X's engines. He used same amount of throttle movement/input which yielded a much different (greater) result from the C56X. We came off the line pretty quickly. This excess speed decreased available response time once it was noticed that the brakes weren't working. It also increased our turn radius and made it impossible to make a 90 degree turn without striking one of the airplanes in front of us.the fact that the captain grabbed the wrong handle is another contributing factor to the incident. He likely did this because it is the only red handle that is in direct view from the captain's seat. The emergency brake handle is in front of the yoke column and not visible unless you move your head to the right or left. We were rapidly approaching the other airplanes and he panicked and grabbed for the first red handle he saw in the vicinity. It's a shame we don't touch that handle more than once a year or so in a simulator during training. If he had grabbed the correct handle I have no doubt that we would have stopped before striking the other airplane. Additionally; had I been able to reach the handle on my first attempt I believe that extra 1/2 second would have enabled us to stop in time.our maintenance team has looked into the brake system and has found no faults and been unable to duplicate. They have replaced the circuit breaker as a precaution. This problem could possibly be helped by requiring additional brake system failures during simulator training or by moving the emergency brake handle to a more visible location.

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Original NASA ASRS Text

Title: C560XL First Officer reported losing the brakes on taxi out of ramp; the pneumatic emergency brakes eventually stopped the aircraft but not before it struck another aircraft. The PWR BRAKES CB was reported tripped. Cessna has issued a service letter cautioning not to use the PWR BRAKES CB as a switch on the C560XL as that can cause the CB to become weak and fail.

Narrative: After a thorough preflight/cockpit setup we waited for passengers to arrive. Once they arrived I loaded the bags and was the last person on the airplane. I was catching up with them as the captain settled into the cockpit. The captain began starting engines. As I sat down in the right seat we monitored the starting of the second engine and I put my seatbelt and headset on. We then checked for a new ATIS and ran the after start/before taxi checklist. I called ground and we were cleared for taxi. The captain applied thrust to get the airplane moving and commented about how the throttles were different from the C550 (He had been flying a C550 during the previous few days). We needed to make a right turn to exit the ramp. As the captain applied right rudder and right brake to steer the airplane he said 'the brakes aren't working.' I tried the brakes on my side; which also did not work. We were rapidly approaching other parked airplanes. He reached for the emergency brake handle but mistakenly pulled the emergency gear release handle and continued pulling on the handle while looking forward at the airplanes we were approaching. I noticed he had grabbed the wrong handle and I quickly reached to pull the correct handle. I was stopped short by my shoulder harnesses on my first attempt. I sat back and got my shoulders free and reached again and pulled the handle. The pneumatic brakes stopped the airplane but our left wing struck the left flap of another airplane on the ramp. We shut down engines. Once stopped we tried to determine why the brakes hadn't worked. The annunciator panel said LOW BRK PRESS and ANTI SKID INOP. I looked over at the circuit breaker panel on the captain's side and noticed that the PWR BRAKES breaker had tripped. I pushed the breaker back in; the hydraulic pump charged the accumulator and I set the parking brake.Cessna has issued a service letter addressing the brake system in the C56X. The letter cautions pilots and maintenance personnel against using the PWR BRAKES circuit breaker as a switch. People pull the breaker to keep the pump from running every couple of minutes and this can cause the breaker to become weak and fail. The letter advises/reminds that without power to the braking system the pilot must use the pneumatic system to stop the airplane. I know pilots and maintenance personnel who have used the breaker in the manner Cessna says not to. It is my belief that the breaker was weak and failed after releasing the parking brake and during the first seconds of the taxi. I know for certain that the breaker was in when we set up the cockpit before passengers arrived. I don't know for certain when it tripped. I am going to give the captain the benefit of the doubt and trust that the breaker was in as he started engines and that he tested the brakes when after releasing the parking brake and before applying throttle. In that scenario; the breaker failed at the absolute worst possible time given our speed and proximity to other aircraft. I believe one contributing factor to this incident is the excess thrust used to get the aircraft rolling. This; I believe; was due to the captain flying a C550 one day and a C56X the next day and not thinking about the much greater performance/response with the C56X's engines. He used same amount of throttle movement/input which yielded a much different (greater) result from the C56X. We came off the line pretty quickly. This excess speed decreased available response time once it was noticed that the brakes weren't working. It also increased our turn radius and made it impossible to make a 90 degree turn without striking one of the airplanes in front of us.The fact that the captain grabbed the wrong handle is another contributing factor to the incident. He likely did this because it is the only red handle that is in direct view from the captain's seat. The emergency brake handle is in front of the yoke column and not visible unless you move your head to the right or left. We were rapidly approaching the other airplanes and he panicked and grabbed for the first red handle he saw in the vicinity. It's a shame we don't touch that handle more than once a year or so in a simulator during training. If he had grabbed the correct handle I have no doubt that we would have stopped before striking the other airplane. Additionally; had I been able to reach the handle on my first attempt I believe that extra 1/2 second would have enabled us to stop in time.Our maintenance team has looked into the brake system and has found no faults and been unable to duplicate. They have replaced the circuit breaker as a precaution. This problem could possibly be helped by requiring additional brake system failures during simulator training or by moving the emergency brake handle to a more visible location.

Data retrieved from NASA's ASRS site 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.