Commercial Fixed Wing
Flight Crew Air Transport Pilot (ATP)
Aircraft Equipment Problem Less Severe; Flight Deck / Cabin / Aircraft Event Smoke / Fire / Fumes / Odor
General Evacuated
Aircraft
During preflight the upper deck cargo fire suppression activated. After upper deck cargo deck door was opened; it was not possible keep Halon from entering the forward vestibule area. To keep the crew from getting sick from breathing Halon; at my insistence; I escorted the forward crew off of the aircraft while passengers were still on board the back part of the aircraft. This was a Combi. No passengers were affected.
Flight Attendants in back called and said they heard a loud POP. First Officer came back and opened sliding door and thick vapor came billowing out and filled vestibule. Mechanics and rampers came within minutes and opened big cargo Door and found that the two 125lb Halon bottles were discharging from the ceiling. I started to feel very lightheaded. Captain told me to step out on the stairs right away to get fresh air. I realized that I was in violation and stepped back in. By the time most passengers were done deplaning I had to get off again to get fresh air. There were still passengers; but I could not stand it any more and had to get air.
Test button activated the upper cargo deck Halon fire suppression system during preflight for a Combi modified aircraft; Crew evacuated the aircraft.