Date: 201506
Local time of day: 1801-2400
Location: ZZZ.Airport, US
Light: Dusk
Aircraft: Citation X (C750)
Operator: Fractional
Operating under: Part 135
Mission: Passenger
Flight phase: Parked
Aircraft component: Elevator ControlSystem
Component problem: Malfunctioning
Reporter organization: Fractional
Reporter function: Technician
Reporter qualification: Maintenance Airframe; Maintenance Powerplant
Human factors: Communication Breakdown
Anomaly: Aircraft Equipment Problem Critical; Deviation / Discrepancy - Procedural Maintenance; Deviation / Discrepancy - Procedural Published Material / Policy; Deviation / Discrepancy - Procedural FAR
Detector: Person Flight Crew
When detected: Pre-flight
Result: General Maintenance Action; General Flight Cancelled / Delayed
Contributing factors: Procedure; Incorrect / Not Installed / Unavailable Part; Human Factors; Company Policy
Primary problem: Human Factors

Narrative: The flight crew reported a noticeable binding/bump in both yoke controls when pulling the control rearward. Mechanic Y and I began troubleshooting.  We first pulled the pitch disconnect to split the pilot's and co-pilot's elevator systems. The problem was clearly in the co-pilot's elevator. We found the cable retaining bolt on the aft elevator sector contacting the elevator feel pushrod. The bolt was too long; causing damage to the pushrod and impeding elevator travel when the elevator was moved upward to nose up position. The damaged pushrod and incorrect hardware were replaced. Clearance and operational checks performed.The aircraft just came out of inspection; attention to detail in the flight control checks should have found this. The CE-750 flight controls feel is all artificial by spring bungees and it is difficult to physically feel the difference between a smoothly operating cable run and one that is obstructed.

Callback: Reporter stated the Captain and co-pilot have separate elevator control cables that run aft to the aft sector crank and transition to push rods in the tail that input to hydraulic actuators for the elevators. The control yoke disconnect is under the cockpit floor. The pilot and co-pilot could technically operate their individual elevators separately. The elevator bungee is actually an electric actuator that changes the mechanical advantage based on air speed by using a moveable beam and springs; more air speed; more tension applied to the elevator feel pushrod that attaches to the Elevator Aft Sector Crank assembly.Reporter stated the longer cable retaining bolt was supposed to be installed on older CE-750 series aircraft that had the Aircraft Manufacturer's Line Assembly Serial Numbers (S/N) that were pre-95. Aircraft with Line S/Ns 95 and later used a shorter bolt. The incorrect longer bolt end would contact the artificial elevator feel input rod just as the elevators became streamlined and the control yoke was moved slightly aft. Elevator did have full range but would have a catch in movement when bolt end contacted pushrods.



Synopsis: A Line Aircraft Maintenance Technician (AMT) reports a flight crew had noticed a binding; bump feel in both yoke controls when pulling the yoke rearward during their preflight on a Cessna CE-750 aircraft. Troubleshooting later revealed an incorrect cable retaining bolt had been installed on the elevator aft sector that would contact the elevator feel pushrod when the elevator yoke was moved to a nose-up position.