Narrative:

When mechanics dropped off aircraft 1 of them told my first officer 'the APU would work fine.' unfortunately, the APU was MEL'ed, and I was not present to question the mechanic on this. Later, the first officer shared with me the mechanic's comment. While parked in a winter wonderland the aircraft became very cold. I decided to try the APU for heat. APU started and ran normally for 5-10 mins, then failed. A small exhaust-pipe fire occurred on shutdown. It was quickly extinguished, with no damage to aircraft. No passenger were on board. The use of MEL'ed equipment at my airline has become common place. I allowed my decision making to be influenced by this, by my desire to maintain a comfortable environment, and by the 'off the record' suggestion of a mechanic. Supplemental information from acn 354708: the APU caught fire and shut itself down but did not fire the fire bottle or give any warning lights. People from the terminal let us know about it. I think people should be aware that if an APU shuts itself down with no warning lights there still could be a problem. If someone had not told us, we may not have become aware of the problem for a couple more mins.

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Original NASA ASRS Text

Title: DHC8 CREW USES THE APU FOR HEAT, UNAWARE THAT IT HAS BEEN MEL'ED. APU HAS A STACK FIRE AND SHUTS DOWN AUTOMATICALLY. A MECH SUGGESTED TO THE CREW THAT IT WAS OK TO USE THE APU.

Narrative: WHEN MECHS DROPPED OFF ACFT 1 OF THEM TOLD MY FO 'THE APU WOULD WORK FINE.' UNFORTUNATELY, THE APU WAS MEL'ED, AND I WAS NOT PRESENT TO QUESTION THE MECH ON THIS. LATER, THE FO SHARED WITH ME THE MECH'S COMMENT. WHILE PARKED IN A WINTER WONDERLAND THE ACFT BECAME VERY COLD. I DECIDED TO TRY THE APU FOR HEAT. APU STARTED AND RAN NORMALLY FOR 5-10 MINS, THEN FAILED. A SMALL EXHAUST-PIPE FIRE OCCURRED ON SHUTDOWN. IT WAS QUICKLY EXTINGUISHED, WITH NO DAMAGE TO ACFT. NO PAX WERE ON BOARD. THE USE OF MEL'ED EQUIP AT MY AIRLINE HAS BECOME COMMON PLACE. I ALLOWED MY DECISION MAKING TO BE INFLUENCED BY THIS, BY MY DESIRE TO MAINTAIN A COMFORTABLE ENVIRONMENT, AND BY THE 'OFF THE RECORD' SUGGESTION OF A MECH. SUPPLEMENTAL INFO FROM ACN 354708: THE APU CAUGHT FIRE AND SHUT ITSELF DOWN BUT DID NOT FIRE THE FIRE BOTTLE OR GIVE ANY WARNING LIGHTS. PEOPLE FROM THE TERMINAL LET US KNOW ABOUT IT. I THINK PEOPLE SHOULD BE AWARE THAT IF AN APU SHUTS ITSELF DOWN WITH NO WARNING LIGHTS THERE STILL COULD BE A PROB. IF SOMEONE HAD NOT TOLD US, WE MAY NOT HAVE BECOME AWARE OF THE PROB FOR A COUPLE MORE MINS.

Data retrieved from NASA's ASRS site as of July 2007 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.