Date: 201602
Local time of day: 0601-1200
Location: ZZZ.Airport, US
Flight conditions: VMC
Weather elements / visibility: 10
Aircraft: Citation V/Ultra/Encore (C560)
Operator: Air Taxi
Operating under: Part 135
Flight plan: IFR
Mission: Ambulance
Flight phase: Climb
ATC / advisory: TRACON ZZZ
Aircraft component: Aileron Trim System
Component problem: Malfunctioning
Reporter organization: Air Taxi
Reporter function: Captain; Pilot Flying
Human factors: Confusion; Troubleshooting
Second reporter function: Pilot Not Flying; Captain
Anomaly: Aircraft Equipment Problem Less Severe
Detector: Person Flight Crew
When detected: In-flight
Result: Flight Crew Landed in Emergency Condition; Flight Crew Overcame Equipment Problem; Flight Crew Returned To Departure Airport; General Maintenance Action
Contributing factors: Aircraft; Human Factors
Primary problem: Aircraft

Narrative: WX was good so PIC accepted flight; first flight of day checks were completed; med crew was loaded; engines started. All before taxi checks were completed and we got a taxi clearance; all taxi and before takeoff checklist was completed. Takeoff roll was normal; and through V1 and Vr everything felt normal; however what I initially noticed was that it was increasingly hard to hold runway heading which was what I was assigned. The yoke control pressure to keep wings level was becoming so hard that it took both hands to accomplish the task; I then checked the trim indicators to see if they were out of whack but the indicators were showing centered or very close. I asked the PNF who was also the PIC to feel the controls; we had a positive exchange of controls then he agreed that there was a control issue at which point he visually checked both the aileron and rudder trim indicators that appeared normal. Once he had control I tried to turn the trim knob and it felt bound but didn't want to overpower it because I was not the PF and could not experience any inputs that I made. We requested to turn back and ATC asked what the issue was and we told them we were having control problems. We turned back to the field and switched controllers. I checked engine gauges to make sure everything else was normal and it was; the PIC was struggling to keep wings level and we discussed if it was harder to hold the faster we went and he said he thought it was; which made me again check the trim indicators but again they looked normal. We were given a visual approach which we accepted; then discussed how we wanted to bring down flaps and gear being cautious not to exacerbate the situation. While on final the PIC again tried adjusting the trim and got movement and the rolling right tendency went away and a normal landing was conducted.

Callback: The reporter believes that several issues were involved in this incident. First; maintenance worked on the aircraft the day prior and this was the first flight after. Second; the reporter does not fly the CE560 very often and was not familiar with the force required to adjust the aileron trim on this aircraft. And last the aileron trim indicator was mis-indexed so the gauge did not reflect that the ailerons were out of trim. Maintenance was able to quickly re-index the aileron trim gauge.

Second narrative: [Report narrative contained no additional information.]


Synopsis: CE560 flight crew experienced a strong rolling tendency and aileron trim binding during initial climb then the controls are passed to the PIC in the right seat. The crew elects to return to the departure airport and the PIC is able to adjust the aileron trim to neutralize the rolling tendency prior to landing.