Narrative:

Prior to boarding our APU failed for a second time. We called maintenance and they deferred the APU. We boarded and handed out paper work when we found out the ground crew lost the pin to the door handle. The ground crew asked us to call maintenance to see if they had spare pins. I called dispatch who then handed me over to maintenance. Maintenance advised me that they would send the mechanics out to help look. While on the phone with maintenance I asked if it was okay with them for us to start an engine because the cabin temperature was dropping rapidly. They said they didn't see a problem with it. I asked the ground crew if it was okay to start engine #2 and they confirmed we were good to start and the aircraft was chocked and hooked up to the tug; but then they walked away. I went outside to make sure #2 was clear and the first officer (first officer) started the engine. While outside I looked around to see if I could see the pin. The mechanics showed up and starting looking for the pin to the door. After a while of looking we could not find the pin and the mechanics disappeared without talking to the crew. I called dispatch to see what was going on and to see if there was any spare pins; or planes we could take. That's when dispatch advised me that we would probably be swapping planes. I told the first officer and he called operations to ask for the jet bridge back to deplane. A few minutes later the gate agent comes down and we deplane. After the last passenger gets off I go to the back of the aircraft to advise the flight attendants what was going on. At that point in time the flight attendants advised me of a possible duty issue for them. A few minutes later the first officer came back to tell us that operations had called and we are switching aircraft. A couple of minutes after that a mechanic ran on board and asked why the #2 was still running. Not knowing it was still running I ran up there and quickly shut the engine down. We then shut down the aircraft and took our bags off and proceeding into the terminal with no incidents. Better communication. Create a checklist for situations like this to warm the aircraft when an APU is MEL'd in extreme cold conditions.

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Original NASA ASRS Text

Title: Dash 8 flight crew reported starting an engine for cabin heat on the ground; then leaving the engine unmonitored when they left the cockpit.

Narrative: Prior to boarding our APU failed for a second time. We called maintenance and they deferred the APU. We boarded and handed out paper work when we found out the ground crew lost the pin to the door handle. The ground crew asked us to call maintenance to see if they had spare pins. I called dispatch who then handed me over to maintenance. Maintenance advised me that they would send the mechanics out to help look. While on the phone with maintenance I asked if it was okay with them for us to start an engine because the cabin temperature was dropping rapidly. They said they didn't see a problem with it. I asked the ground crew if it was okay to start engine #2 and they confirmed we were good to start and the aircraft was chocked and hooked up to the tug; but then they walked away. I went outside to make sure #2 was clear and the First Officer (FO) started the engine. While outside I looked around to see if I could see the pin. The mechanics showed up and starting looking for the pin to the door. After a while of looking we could not find the pin and the mechanics disappeared without talking to the crew. I called dispatch to see what was going on and to see if there was any spare pins; or planes we could take. That's when dispatch advised me that we would probably be swapping planes. I told the FO and he called operations to ask for the jet bridge back to deplane. A few minutes later the gate agent comes down and we deplane. After the last passenger gets off I go to the back of the aircraft to advise the flight attendants what was going on. At that point in time the flight attendants advised me of a possible duty issue for them. A few minutes later the FO came back to tell us that operations had called and we are switching aircraft. A couple of minutes after that a mechanic ran on board and asked why the #2 was still running. Not knowing it was still running I ran up there and quickly shut the engine down. We then shut down the aircraft and took our bags off and proceeding into the terminal with no incidents. Better communication. Create a checklist for situations like this to warm the aircraft when an APU is MEL'd in extreme cold conditions.

Data retrieved from NASA's ASRS site and automatically converted to unabbreviated mixed upper/lowercase text. This report is for informational purposes with no guarantee of accuracy. See NASA's ASRS site for official report.