NTSB Identification: NYC99IA231.
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Incident occurred Friday, September 17, 1999 in COVINGTON, KY
Probable Cause Approval Date: 05/09/2001
Aircraft: McDonnell Douglas MD-88, registration: N947DL
Injuries: 118 Uninjured.

NTSB investigators used data provided by various sources and may not have traveled in support of this investigation to prepare this aircraft incident report.

On departure climb, the flight attendants smelled something burning. Then a passenger noticed a 'glow' in the right side air vent near his feet and reported that the cabin floor was warm. Halon was sprayed into the vent, and the glow disappeared. The pilot declared an emergency and returned to the departure airport. The airplane was stopped on the runway and based upon reports from emergency personnel, an emergency evacuation was performed. Thermal damage and sooting was found on the right side underside floor structure, a nearby fiberglass bin wall panel, and a potable water bottle. A 5-foot by 5-foot area of insulation, which consisted of fiberglass, covered on both sides with a metallized mylar, was burned. The right side, alternate static port heater lay under the insulation. The insulation on one of the wires leading to the heater was found to be deteriorated and melted where it was bent around the thermostat case. Evidence of metal transfer was found between the solid-core wire and the adjacent heater case. Soot was found on the insulation covering the wire and adjacent heater case. The heater was manufactured with the wire bend.

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

Deteriorated wire insulation and shorting at a short radius bend to the electrical wiring in the right side alternate static port heater, which resulted in electrical arcing and a fire sustained by overlaying thermal acoustic insulation.

Full narrative available

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