Date: 201904
Local time of day: 1201-1800
Location: ZZZ.ARTCC, US
Weather elements / visibility: VMC; 10
Aircraft: Citationjet (C525/C526) - CJ I / II / III / IV
Operator: Corporate
Operating under: Part 91
Flight plan: IFR
Mission: Passenger
Flight phase: Climb
Airspace: Class A ZZZ
ATC / advisory: Center ZZZ
Aircraft component: Aeroplane Flight Control
Component problem: Malfunctioning
Reporter organization: Corporate
Reporter function: Pilot Flying; Captain
Reporter qualification: Flight Crew Multiengine; Flight Crew Flight Instructor; Flight Crew Instrument
Human factors: Troubleshooting; Confusion
Anomaly: Aircraft Equipment Problem Critical; Inflight Event / Encounter Loss Of Aircraft Control
Detector: Person Flight Crew
When detected: In-flight
Result: Flight Crew Regained Aircraft Control; Flight Crew Diverted
Contributing factors: Aircraft; Human Factors; Procedure
Primary problem: Ambiguous

Narrative: I experienced uncommanded roll of the aircraft during climbout [at 3;000 feet AGL]. Had critical control problems that required my full attention to keep the aircraft from rolling over. Required full left aileron and full right rudder and aileron trim to keep the aircraft in a level flight attitude. Was in contact with ZZZ Center a few minutes after this happened. ZZZ Center handed me off to ZZZ1 Center. As I recall I communicated that I was having aircraft control problems; but at the time did not indicate the severity of the problem. I could not engage the A/P (autopilot). Felt I had to get to a higher altitude. I accepted a climb clearance to FL260. I had difficulty leveling off and overshot by 500 feet. It also took me a few minutes to correct down to FL260; since I was continuing to experience aircraft control issues. I was busy trying to troubleshoot the problem all during this time. At no time could I remove my hand from the control yoke; until leveling off at cruise altitude when I was able to re-engage the A/P. The control issues were attributed to a malfunction of the Tamarack Winglet System.The left TACS control surface was jammed in the full down position and the right TACS was in a neutral position. Remained so for the remainder of the flight. Tried to do an emergency reset of the system in flight; but was unable to reset the winglet system. Decided to burn fuel to lighten the aircraft and divert.

Callback: Reporter indicated flight was a single pilot operation and had flown this aircraft with the Active Winglet modification for over 1.5 years. Captain was made aware of the recently issued EASA Emergency Airworthiness Directive and elected to deactivate the Active Winglet system by pulling the associated three circuit breakers. After takeoff; at approximately 3;000 feet AGL; the aircraft began the uncommanded roll. Narrative should read full left rudder rather than full right rudder was required along with full left aileron to maintain level flight. TACS control surface on the left wing was still found in the displaced position after landing. The aircraft will not be operated until the ATLAS Service Bulletin has been accomplished.



Synopsis: C525 Captain reported uncommanded roll issues associated with a jammed ATLAS Active Winglet system.