Porter DH8D at Montreal on Jul 2nd 2014, uncommanded roll

A Porter Airlines de Havilland Dash 8-400, registration C-GLQD performing flight PD-419 from Toronto City,ON to Montreal,QC (Canada) with 37 people on board, was descending through FL200 towards Montreal with the autopilot engaged when the aircraft uncommandedly and aggressively rolled to the right reaching a bank angle of 20 degrees, the autopilot automatically disconnected. The crew stopped the roll with manual control inputs, then noticed indications "YD not centered" and "AP disengaged". Approximately 2 seconds after the uncommanded roll another indication "Fuselage Doors" illuminated, the pilot monitoring checked the door ECAM page and found door 2L indicated red. The purser reported the door appeared to be closed and was instructed to not go near the door. The crew subsequently received information that a flight attendant was injured. The crew observed that the pressurization of the aircraft appeared normal, the aircraft controls also appeared normal. The crew declared PAN reporting a possible door issue and also reporting an injured flight attendant, then slowed the aircraft for the rest of descent without autopilot. The aircraft landed safely on Montreal's runway 24R about 15 minutes after the PAN call.

The Canadian Transportation Safety Board (TSB) reported that the occurrence happened in clear skies with no significant weather reported. following the event examination of the flight data monitoring and of the aircraft did not find any anomalies, the aircraft was returned to service. The cockpit voice and flight data recorders were forwarded to the TSB for investigation.