Date: 201701
Local time of day: 0001-0600
Location: ZZZ.Airport, US
Flight conditions: VMC
Light: Night
Aircraft: Citation Excel (C560XL)
Operating under: Part 135
Flight plan: IFR
Mission: Passenger
Flight phase: Takeoff / Launch
ATC / advisory: Tower ZZZ
Aircraft component: Nosewheel Steering
Component problem: Improperly Operated
Reporter function: Captain; Pilot Not Flying
Reporter qualification: Flight Crew Air Transport Pilot (ATP)
Human factors: Situational Awareness
Anomaly: Aircraft Equipment Problem Less Severe; Deviation / Discrepancy - Procedural Published Material / Policy
Detector: Person Flight Crew
When detected: Taxi
Result: Air Traffic Control Provided Assistance; Flight Crew Rejected Takeoff; Flight Crew Requested ATC Assistance / Clarification; General Maintenance Action
Contributing factors: Human Factors; Aircraft; Procedure
Primary problem: Human Factors

Narrative: Upon arrival our passengers were escorted by the PIC and transported to the aircraft by FBO staff. SIC had competed the preflight activities and passengers were boarded. PIC did a final walk around. Neither crew member noted any discrepancies prior to the flight.[Airport] was the site of [a sporting event] and the airport was heavily congested with aircraft; so all taxiing was done at a slow pace. We were cleared to taxi from the [FBO] ramp onto Taxiway 'Z' and to hold short of Taxiway 'Z1'; and to expect Runway 'ZZ'. With the marshal's signal be began taxiing straight ahead for about 20 feet and made a left turn heading for Taxiway 'Z'. As we approached 'Z' the pilot flying said the steering felt a little sluggish and asked if I had checked the torque link pin. I said I had done my final walk around; but didn't notice anything abnormal; however wasn't 100% sure that the torque link pin itself was installed. I decided to make a few turns left and right to insure we had the torque link connected. In addition to the initial 90 degree turn as we began to taxi; the pilot flying made turns of approximately 45 degrees left and right. Both crew members were satisfied that the torque pin 'must' have been installed or else we would not have been able to steer the aircraft with nose wheel steering.[Airport] was the site of [a sporting event] and the airport was heavily congested with aircraft so all taxing was at a slow pace. We entered onto Taxiway 'Z'; turning left and held short of Taxiway 'Z1'. Once cleared; we turned left onto Taxiway 'Z1' and continued to taxi in line with multiple other aircraft to Runway 'ZZ' with no steering problems. We turned right at Taxiway 'Z2' and held short awaiting our takeoff clearance on Runway 'ZZ'. Once cleared for takeoff; we turned right onto Runway 'ZZ' and began our takeoff roll.As we accelerated to approximately 20-30 knots; we felt excessive nose wheel shimmy and aborted the takeoff. Pilot not flying notified Tower of the aborted takeoff and we exited the runway onto Taxiway 'Z'; holding short of Taxiway 'Z3'. Contacting Ground; we were given taxi instructions straight ahead on 'Z' and then onto the [FBO] ramp. The pilot flying taxied very slowly turning right onto [FBO's] ramp and left to parking as instructed by the lineman marshal.We secured the aircraft and the PIC exited to check the torque link. Finding the pin installed; PIC went back and informed the SIC that the pin was installed; and that he was going inside the FBO to call Flight Control and Maintenance Control. When the PIC exited again; the marshal informed him that he noticed the 'steering scissors' were disconnected; so he connected them and installed the pin.PIC notified Flight Control and Maintenance Control and described the events. Maintenance requested pictures of the torque link from two different angles with the pin installed. A maintenance technician was dispatched to inspect the nose gear assembly and the PIC made a discrepancy report in the Aircraft Maintenance Log (AML). The maintenance technician performed a thorough inspection and completed the maintenance log noting no discrepancies found. Maintenance Control and Flight Control released the flight to continue.The flight was continued uneventfully.Note: While waiting for a maintenance technician to arrive; the PIC discussed with one of the senior lineman at the front desk of [the FBO]; the torque link being disconnected; and then not reconnected by FBO personnel after repositioning our aircraft. He informed me that they typically disconnect the torque links when towing aircraft to parking locations. However; he said that they also reconnect the torque links after they move aircraft. He was very surprised and apologetic that we had this problem. He happened to be the lineman marshal who directed us on our initial movement from our parking spot. He said he was very surprised the torque link was found disconnected as he said he always checksthese links when he is directing aircraft movement. He thought ours was connected; but said he really wasn't sure as it was difficult to see in the darkness and the aircraft appeared to be turning with no problems. At my request; he double checked with the lineman who said he noticed the 'steering scissors' were disconnected as we taxied back to parking. He confirmed that the lineman had reconnected the torque link before I had gotten out of the aircraft to check for myself.If there is ever something that doesn't feel right with steering control on the ground; or a question concerning the status of the torque link pin being installed; the aircraft should be stopped and the torque link status confirmed to be ready for flight. Maintenance should be consulted before continuing.All of our Citation XL's have torque links. Some of them have torque link 'pins' while others have the torqued links connected with a 'bolt' to prevent the exact problem we had. I suggest all of our XL's have the torque link connected with a 'bolt' vs. the 'pin'.Crews must insure the status of the torque link prior to operating the aircraft. Be aware of your expectation that things are normal and make sure appropriate checks are conducted.




Synopsis: The Captain of a Cessna 560XL reported they rejected takeoff due to a nose wheel shimmy. It was discovered that the nose gear scissors were disconnected.