Cessna Citation Sovereign (C680)
Flight Crew Air Transport Pilot (ATP)
Aircraft Equipment Problem Critical; Flight Deck / Cabin / Aircraft Event Smoke / Fire / Fumes / Odor; Ground Event / Encounter Other / Unknown
Flight Crew Overcame Equipment Problem; General Maintenance Action
Aircraft
While I was in cockpit partner said there is a strange smell. I went back and agreed it was strong and was calling Maintenance and saw smoke coming from floor below lav sink. Then a 4 to 6 inch flame appeared. I yelled; 'fire turn off bleed air'. He did that grabbed the fire extinguisher and headed back. The smoke and flames stopped when the bleed was turned off so extinguisher was not used. We got off the aircraft and wrote it up. In hindsight I should have had the cabin interior switch turned off also to cut the most likely source of the fire. We would have been airborne in about 30 minutes glad it happened on the ground.
While preparing for departure the flight crew of a CE-680 reacted quickly to smoke and fire emanating from the cabin floor beneath the lavatory sink; apparently the result of a faulty pneumatic system.