Dash 8-200
Flight Crew Air Transport Pilot (ATP)
Aircraft Equipment Problem Critical; Flight Deck / Cabin / Aircraft Event Smoke / Fire / Fumes / Odor
Flight Crew Overcame Equipment Problem
Aircraft
The departure and cruise segments of the flight were uneventful. While initiating an initial descent I heard a pop and noticed arcing on the electrical terminals on the window directly in front of me. I brought it to the Captain's attention. Almost immediately a torch-like fire occurred at the terminals making a loud hissing sound. Shortly after that; the torch like fire ignited the plastic in the vicinity of the electrical terminals causing a flame. We donned our oxygen masks and started fighting the fire. We transferred controls of the plane while I discharged the fire extinguisher at the fire. The flames ceased; but the arcing occurred again which reignited the fire. I discharged the fire extinguisher a second time and the fire flared up again. At that point we transferred controls back and I increased airspeed to Vmo while the Captain ran check lists and coordinated an evacuation plan with the Flight Attendant. I informed ATC of our intentions and they pushed us to the Tower frequency shortly thereafter. Once we were on short final approach we configured the aircraft and landed without incident. Once on the ground we transferred controls as normal turned onto a taxiway and stopped short of a parallel taxiway and executed the emergency evacuation procedure as planned. Everyone exited the aircraft without injury and met up at the rally point.    Since this event involved the window heat; perhaps a maintenance inspection at specific intervals may prevent a recurrence of this event
Due to the nature of the fire and it being persistent; I called the Flight Attendant using my mask; and told her that there was a fire present in the cockpit and since I wasn't sure if it would flare back up; to plan on an emergency evacuation when we got on the ground. Somehow the call dropped.
Dash-8 201 flight crew reported a persistent fire caused by arcing at the First Officer window terminals.