Date: 201304
Local time of day: 1801-2400
Location: ZZZ.Tower, US
Flight conditions: VMC
Light: Night
Aircraft: Dash 8-100
Operator: Air Carrier
Operating under: Part 121
Mission: Passenger
Flight phase: Initial Approach
Airspace: Class A ZZZ
ATC / advisory: Tower ZZZ
Aircraft component: Aeroplane Flight Control
Component problem: Malfunctioning
Reporter organization: Air Carrier
Reporter function: Captain; Pilot Flying
Reporter qualification: Flight Crew Air Transport Pilot (ATP)
Human factors: Other / Unknown
Anomaly: Aircraft Equipment Problem Critical; Deviation / Discrepancy - Procedural FAR; Inflight Event / Encounter Other / Unknown
Detector: Person Flight Crew
When detected: In-flight
Result: Flight Crew Landed As Precaution; Flight Crew Diverted
Contributing factors: Aircraft; Human Factors
Primary problem: Aircraft

Narrative: After leveling at 18;000 feet with the autopilot on and accelerating to cruise speed and trimming the rudder I noticed that the both yokes were deflected left to maintain level flight. I brought this up with my First Officer and then I checked the PFCS indicator to make sure there were no spoilers deflected and none were. I then looked down at the aileron trim and it was close to max left wing down. I then disconnected the autopilot and the aircraft immediately began a slow roll to the right. I was able to counter that by turning the yoke to the left and maintaining level flight and verified we could still turn the aircraft to the left. I placed the yoke in the neutral position and the aircraft immediately rolled right. We discussed our situation and position in the flight and decided to call Dispatch and Maintenance and confer with them. While on the call with them myself and the First Officer decided to go ahead and divert to ZZZ and make a precautionary landing rather than proceed to destination and risk the problem worsening. Plus we knew by diverting to ZZZ the aircraft could immediately be looked at by our mechanics and we would be able to swap aircraft and continue on to ZZZ1 with our passengers. We notified ATC then the First Officer briefed the Flight Attendant and the passengers that we were diverting due to a mechanical issue with the aircraft. We were able to maintain positive control of the aircraft at all times and made a normal landing without declaring an emergency. After deciding to divert to ZZZ due to a mechanical problem we were on a visual approach to Runway 13 at ZZZ we were illuminated by a green laser. Once we realized what was happening the First Officer instinctively extinguished all exterior lights and the laser illumination immediately st opped. We then notified ATC that we had experienced a laser beam directed at us and that we had extinguished all our lights. We relayed where the illumination originated from which was just south of a ridge line and approximately 5 miles to the east of our position which was about 8 miles northwest of the airport descending through 3;000 feet. Neither I nor the First Officer was physically affected and we continued for a normal landing and approach. I saw a green flash out the left side of the aircraft thinking it was fireworks looked and quickly realized it was a laser. Apparently someone had nothing better to do on a Saturday night other that shining their laser at airplanes.




Synopsis: DHC8-100 Captain detects a flight control fault in cruise flight and elects to divert for maintenance. During the approach the aircraft is illuminated by a green laser.