Dash 8-300
Flight Crew Air Transport Pilot (ATP)
Flight Crew Type 3500
Aircraft Equipment Problem Less Severe; Deviation / Discrepancy - Procedural Published Material / Policy; Flight Deck / Cabin / Aircraft Event Smoke / Fire / Fumes / Odor
Air Traffic Control Provided Assistance; Flight Crew Requested ATC Assistance / Clarification; General Maintenance Action
Aircraft; Procedure; Human Factors
We taxied out from the gate on one engine because we had about a 20 minutes wheels up time. ATC told us to hold short of taxiway A for our wheels up time. After a few minutes of waiting; I noticed smoke coming from the left side (we had a small tailwind) I saw that it was coming from the base of the number. 1 propeller hub. I looked up to the de-ice panel and saw that the propeller heat switch was turned on (Propeller timer 1 above -10) and the advisory lights indicated the propeller heat was on and going through its cycle. I turned it off immediately; and noticed the advisory lights stayed illuminated. At this point the smoke at the propeller hub was getting worse and flames started to appear. I turned the aircraft into the wind and told my First Officer to call the station and inform them. I set the brake and told Ground to roll the trucks and that our number 1 engine was on fire. The fire seemed to be getting worse and I thought we might have to evacuate out the right side so I shut everything down. As soon as it was shut down; the fire stopped. About this time the trucks showed up. We opened the main door I exited to talk to the fire people. They confirmed that the fire was out. Operations showed up and we determined that it was best to deplane there and have the people walk back to the terminal. Operations chocked the plane; put up cones and we deplaned. In the end; we did not declare an emergency and did not evacuate. No one was injured; and the passengers seemed to be in good spirits.The propeller timer switch was on when we got to the plane. We didn't notice it when [we] swapped in. There is supposed to a redundant system that prevents the propellers from heating up while on the ground. I assume this system failed; because it clearly heated up. We tried to turn the system off via the switch. I'm not sure if that actually worked; the advisory lights continued to cycle. We notified ATC and OPS. We shut the aircraft down and deplaned after the fire/rescue people confirmed the fire was out.I am not sure why the switch was left on. If I saw it prior to starting the engines I would have turned it off. But the system is not supposed to have power on the ground unless you push the Test switch. (I checked the position of the test switch; after the people deplaned. It was in the normal position). If I had started both engines; it is possible the heat would have been on; but the propellers might not have overheated. The other engine showed no signs of damage to the propeller.
Dash 8 Captain reported shutting down the aircraft on the taxiway after noticing smoke and flames from the left engine propeller area. Propeller heat switch was discovered to have been in the on position from the previous flight.