DEN07IA037
NTSB Identification: DEN07IA037.
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Scheduled 14 CFR operation of Continental Airlines, Inc. (D.B.A. Commercial Service)
Incident occurred Friday, December 15, 2006 in Colorado Spring, CO
Probable Cause Approval Date: 6/27/2007
Aircraft: Boeing 737-824, registration: N24202
Injuries: 1 Minor, 159 Uninjured.

The passenger was wearing an Ecoquest Fresh Air Buddy Personal Air Purifier around his neck. According to the manufacturer, it "generates an intense electrostatic ion wind that charges floating particles in the 'breathing zone.' The particles are substantially repelled away from the wearer, creating an almost particle-free 'exclusion zone' for toxic allergens, smoke, dust, viruses, and bacteria. Perfumes and odors can also be minimized by the ion particle-charging-effect." The passenger was observed to be holding a Sprint Trio 700 camera phone up to the window, sometimes talking into it, but he claimed he was only taking photographs. As he held his telephone to the window, there was a noise that sounded "like a fuse." There was a flash and a loud bang, and smoke emanated from the device. The passenger yelled and flung the air purifier from around his neck because it had started to burn him. It exploded into a ball of flames "about the size of volleyball" and fell between the seat cushions, starting a fire. Passengers poured water and other liquids on the smoldering cushions, and a flight attendant used a Halon fire extinguisher to put the fire out. The battery was never recovered. NTSB's fire and explosion expert examined the device. Her report stated that the air purifier originally came with a 3.6V CR123A non-rechargeable lithium primary battery, but a kit containing a charger and a rechargeable lithium-ion battery was available for purchase. The battery compartment cover was melted and deformed, and had two areas of metal splatter. Analysis of this splatter revealed the presence of manganese. Manganese dioxide is a component in primary (non-rechargeable) lithium batteries. The report noted that a short circuit is the most common cause of battery fires, and that charging a non-rechargeable battery could cause an internal short that could lead to thermal runaway, battery failure, and possibly an explosion.

The National Transportation Safety Board determines the probable cause(s) of this incident as follows:

A short circuit in the primary (non-rechargeable) battery, most likely due to it being recharged. This internal short led to thermal runaway, battery failure, and an explosion.

Full narrative available

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