Date: 202011
Local time of day: 1801-2400
Location: ZZZ.Airport, US
Flight conditions: VMC
Light: Daylight
Aircraft: Citation II S2/Bravo (C550)
Operator: Air Taxi
Operating under: Part 91
Flight plan: IFR
Mission: Other Fly back from maintenance
Flight phase: Taxi
Airspace: Class E ZZZ
ATC / advisory: CTAF ZZZ
Aircraft component: Throttle/Power Lever
Component problem: Malfunctioning
Reporter organization: Air Taxi
Reporter function: First Officer; Pilot Not Flying
Reporter qualification: Flight Crew Multiengine; Flight Crew Instrument; Flight Crew Flight Instructor; Flight Crew Commercial
Human factors: Communication Breakdown; Workload; Confusion
Anomaly: Aircraft Equipment Problem Critical; Deviation / Discrepancy - Procedural Published Material / Policy; Ground Excursion Taxiway
Detector: Person Flight Crew
When detected: Taxi
Result: General Maintenance Action
Contributing factors: Aircraft; Human Factors
Primary problem: Human Factors

Narrative: The aircraft had just finished coming out of engine hot section inspections and we were going to fly it back home. After engine start everything was good. It was my leg back home and my Captain was going to be alert for any engine indicator abnormalities. As we taxied out to Runway XX everything seemed normal. Right before takeoff we briefed that incase of any engine abnormalities that he would take the controls and we would come back to land. As I cleared the area for any traffic and pulled onto the runway he told me to do a static takeoff so we could check for any abnormalities. I applied full power and when I went to bring back the power slightly back to match our takeoff power setting I noticed that I couldn't get the right throttle to come back. At that point my Captain took over the controls and tried to get the engine to idle. My Captain decided to get it off the runway and taxi away from hazardous areas. As we were vacating the runway he cut the left engine. While he was trying to shutdown the right engine on the taxiway the right brake failed and yawed us to the left into dirt where we stopped. My Captain called for emergency services and asked me to open the door and then evacuate. As I was getting out of the plane the right T/R (Thrust Reverser) deployed and dust filled the cabin and reduced visibility. Eventually the engine was shut down with the engine fire wall shut off switch. Luckily no one was hurt and no damage to property happened. It could've been worse if we never did the static take off. It allowed us to find that there was a problem before we took flight. I feel like my Captain could've made a better choice in perhaps not getting off the runway and just holding on tight in a spot. I felt him rush which tunnel visioned him to not call for the checklist. As for me I got tunnel visioned as well and I failed to think outside the box because I looked up to him and followed his decisions. Everything happened so fast and because he decided to exit the runway our workload and vigilance for the environment around us increased. I feel that if we would've just stayed there he would've been able to think clearly and call for the checklist which would've immediately reminded us about the engine fire wall shut off switch. Instead of delaying that reminder of that system due to moving the aircraft; being in the heat of the moment; and having a right side brake failure.




Synopsis: C550 First Officer reported a right throttle malfunction which resulted in a right brake failure and taxiway excursion.