CE560 flight crew reported an autopilot malfunction resulting in a return to the departure airport.

Attributes
ACN	1569866
Time
Date	201808
Local Time Of Day	1801-2400
Place
Locale Reference	ZZZ.Airport
State Reference	US
Environment
Flight Conditions	VMC
Light	Night
Aircraft 1
Make Model Name	Citation V/Ultra/Encore (C560)
Operating Under FAR Part	Part 135
Flight Phase	Initial Climb
Route In Use	Vectors
Flight Plan	IFR
Component
Aircraft Component	Autopilot
Person 1
Function	First Officer Pilot Not Flying
Qualification	Flight Crew Instrument Flight Crew Commercial Flight Crew Multiengine
Experience	Flight Crew Last 90 Days 59.4 Flight Crew Total 801.1 Flight Crew Type 94.4
Person 2
Function	Captain Pilot Flying
Qualification	Flight Crew Air Transport Pilot (ATP) Flight Crew Flight Instructor Flight Crew Instrument Flight Crew Multiengine
Experience	Flight Crew Last 90 Days 42 Flight Crew Total 7800 Flight Crew Type 280
Events
Anomaly	Aircraft Equipment Problem Critical Deviation - Procedural Clearance Deviation - Procedural Published Material / Policy Deviation - Track / Heading All Types

Narrative:

In compliance with the SID we were climbing to the assigned altitude departing ZZZ on the zzzzz departure. We were assigned a new heading to proceed northwest bound. The captain set the new heading then we quickly noticed that the autopilot was not engaging. The captain was able to use the touch control steering to initiate the turn to the assigned heading. Shortly after; the aircraft started a sudden left roll which was unexpected. This was when we attempted to disengage the autopilot. The captain asked me to inform ATC that we needed to return back to ZZZ. We were able to regain directional control. We landed at ZZZ; VFR conditions with no issues.

Original NASA ASRS Text

Title: CE560 flight crew reported an autopilot malfunction resulting in a return to the departure airport.

Narrative: In compliance with the SID we were climbing to the assigned altitude departing ZZZ on the ZZZZZ departure. We were assigned a new heading to proceed northwest bound. The Captain set the new heading then we quickly noticed that the autopilot was not engaging. The Captain was able to use the Touch Control Steering to initiate the turn to the assigned heading. Shortly after; the aircraft started a sudden left roll which was unexpected. This was when we attempted to disengage the autopilot. The Captain asked me to inform ATC that we needed to return back to ZZZ. We were able to regain directional control. We landed at ZZZ; VFR conditions with no issues.

Data retrieved from NASA's ASRS site and automatically converted to unabbreviated mixed upper/lowercase text. This report is for informational purposes with no guarantee of accuracy. See NASA's ASRS site for official report.