EMB-505 flight crew reported brake failure while holding short on taxiway. Flight crew maneuvered away from the area and set the parking brake.
Synopsis
EMB-505 flight crew reported brake failure while holding short on taxiway. Flight crew maneuvered away from the area and set the parking brake.
Narrative
On Day 0 while acting as Pilot Flying (PF) of the aircraft at ZZZ we had taxied from the FBO via taxiway 1 to runway XXR. Upon reaching XXR departure end; at [taxiway] 2; I approached the hold short line and stopped. Because we were number one for departure; I elected to hold the brakes rather than set the parking brake. An airline had been cleared by ZZZ Tower to land on runway XXR. In my estimation we had been sitting at the hold short line for between 30 and 60 seconds. Without warning the brakes failed and the aircraft began to roll toward the hold short line. After quickly confirming that braking was ineffective from both positions (PF and Pilot Monitoring (PM)); while near simultaneously receiving and recognizing the BRK FAIL CAS message it was determined the best course of action was to provide full left rudder turning the aircraft east on 2 and then north on 1 to the non-movement area directly north of 2. Throughout this movement the aircraft continued to accelerate. While I was maneuvering the aircraft on the taxiway(s) the PM made a declaration to ZZZ Tower of our failed brakes. Once clear of the taxiway and onto the non-movement area the PM applied the Parking Brake bringing the aircraft to a stop. Once stopped the Quick Reference Handbook (QRH) was reference for the BRK FAIL CAS message and our company maintenance was consulted. It was determined by the crew and maintenance that the best and safest course of action was the hold in position until a tug could be arrange to tow us back to the FBO. Once the tug arrived; we shut down the engines and were towed back without incident.Once stopped; the PM advised the passengers of the situation and began to coordinate as appropriate with the companies Operations. ZZZ Tower had [requested priority handling] for us which resulted in Emergence Vehicles (Crash; Fire; Rescue) responding to our location. It is my recollection the ZZZ Tower asked for further details at which time our response was to standby". The Fire Chief visibly inspected our aircraft and could not see any leaking fluids and also checked taxiway 2 for hydraulic fluid to which he reported that he did not observe any. Once assured that we were okay and not in need of their services the Emergency response vehicles departed. It is my understanding one emergency vehicle remained behind along with a ZZZ Airport Authority vehicle to provide an escort for our tow back to the FBO. At no time did the aircraft cross over the hold short line of Runway XXR. Once stopped in the non-movement area north of 2; all aircraft on 1; west of 2 were able to move up to 2and depart on Runway XXR. At least one aircraft on 1; east of 2 was blocked by our position. The only indication of a problem prior to the brake failure was a chatter or slipping of the brakes while coming to a stop at the hold short line of Runway XXR. Both crew members observed/heard the noise but attributed it to what appeared to be metallic plates or dissimilar material as part of the taxiway. A preflight inspection and final walk around inspection had been conducted with no abnormalities observed. This aircraft was flown earlier on this day from ZZZ1 to ZZZ by this crew with no observed deficiencies in the braking. A post flight inspection of the aircraft revealed no observed concerns; abnormalities; or deficiencies with the brakes or hydraulics. Once stopped; the PM advised the passengers of the situation and began to coordinate as appropriate with company Operations. My initial detection of the brake failure was the forward movement of the aircraft while I was applying brake pressure. Near simultaneous to that was a BRK FAIL (Brake Failure) CAS message received in the cockpit on the Primary Flight Display.At this time I cannot speculate what caused the brakes to fail. After confirmation of the brake failure the crew reaction was to steer the aircraft away from the active runway and onto the taxiway. Fortunately;there was a non-movement area north of 2 which was the safest location to move towards. With momentum and acceleration building; the aircraft was brought to a stop through the application of the parking brake. ZZZ Tower was advised of the brake failure when and as appropriate.I do not have any confirmed indications of impending brake failure to pass on to other aircrew at this time. We were fortunate that 2 was wide enough for us to maneuver and that there was empty ramp space north of 2 for us as well. My only recommendation would be to approach every hold short line with a planned exit strategy should they have a similar experience. In absence of addition details provided to ZZZ Tower by us; I appreciate their response with Emergency vehicle."
Second reporter narrative
On our leg from ZZZ to ZZZZ; while holding short of XXR at [taxiway] 1; the aircraft's brakes failed; the brake fail CAS illuminated; and the aircraft began rolling forward. We immediately maneuvered the aircraft away from the hold short line to prevent crossing into the active runway with traffic landing and advised tower of the brake failure. We moved the aircraft to a portion of the ramp behind us; as clear from the taxiway as possible. We ended up utilizing the parking brake abruptly to prevent reentry into the active taxi way. ATC understood our transmission and sent equipment to verify there was no damage or leakage from the aircraft on the taxiway and ramp area. We utilized the QRH once stopped; however the actions were for an aircraft inflight not already on the ground aside from the landing portion. No damage was found and a tow back to the FBO was arranged via ramp control. At no point did any portion of the aircraft cross the hold short line. Maintenance and dispatch were advised promptly to work on solutions both for the broken plane and to minimize the impact to our clients. When it was safe to do so; we also advised the passengers of the situation. We were towed back with no further incidents.The parking brake was off as; we were next in line for departure and while waiting for our take off clearance we noticed the aircraft started rolling forward. Then the brake fail CAS immediately illuminated as it became apparent we had completely lost all normal braking. The only thing of note was; when we initially stopped at the hold short line; braking did feel slightly strange; almost as if the brakes were very slightly grabbing then releasing. However; this was so minor it could be easily chocked up to normal Phenom braking behavior or the wheels loosing a little traction on the metal parts of the taxi centerline lights.The cause is unknown at this time. The hydraulic pressure and emergency brake accumulator pressure were normal on the systems page. The hydraulic reservoir was properly checked prior and was in the green. The hydraulic reservoir DPI's were also normal. There were no electronic warnings either that the brakes may fail. The previous flights also had all been completed without incident; including the flight inbound that had been completed about an hour prior.After making the determination that we lost normal braking and with little time to determine anything else prior to entering the runway area with landing traffic; the crew promptly maneuvered the aircraft to an empty ramp area behind us before any portion of our aircraft passed the hold short line. ATC was advised as soon as the aircraft started moving under its own power. We came to a complete stop utilizing the emergency brake. Then we utilized the QRH; contacted maintenance; flight communications; advised our passengers; and coordinated with ramp control to get a tow back to the FBO.I believe we handled this as best we could; given the situation; as there were no real warning signs the brakes were about to fail and we had no real time to determine if this was a total brake failure or an electronic command issue. That said; adding a training discussion or action during IOE where there is little time to make a critical decision with failed braking to help prompt pilots to utilize the parking brake and come up with other solutions to bring the aircraft to a complete stop if that fails; may be beneficial as guidance for any future similar events.
Source: NASA Aviation Safety Reporting System (public domain). Reports are voluntary submissions and are not verified by NASA.