Canadian North B733 at Fort MacKay on Dec 17th 2013, uncommanded left roll despite full right ailerons

A Canadian North Boeing 737-300, registration C-FGCN performing flight 5T-1517 from Fort MacKay Albian,AB to Edmonton,AB (Canada) with 139 people on board, was climbing through about 800 feet AGL when the aircraft began to uncommandedly roll left. The crew countered by applying full right ailerons, the roll to the left however continued. Airspeed began to decay, the crew applied nose down inputs, however, the aircraft reached a nose up attitude of 28 degrees despite the control column commanding nose down. The airspeed finally recovered and increased permitting the crew to retract the flaps after which the left roll ceased. The crew checked engine parameters and configuration with no anomalies detected and decided to continue the flight to Edmonton for a safe landing with no further anomaly observed.

The Canadian TSB reported the occurrence for the first time on Jun 23rd 2014 stating, that the weather conditions at Fort MacKay's Albian's Airport were -22 degrees C with moderate snow. Immediately prior to departure the aircraft was de-iced with type I followed by type IV fluid. Departure roll and rotation were normal. According to flight data recorder the aircraft reached a maximum left bank angle despite maximum right ailerons and a pitch attitude of 28 degrees despite the control column in a 10 degrees nose down position. After the speed recovered the crew retracted the flaps, the left roll ceased, the crew checked engine thrust settings and leading edge devices, all parameters were normal. The crew decided to continue the flight to Edmonton without declaring emergency. The crew used a reduced flap setting for landing. The airline and Boeing are further investigating the event.