Alaska Airlines McDonnell Douglas DC-9-83 incident

While taxiing to parking following a normal landing, the cabin crew notified the flight crew that an electrical smelling smoke was engulfing the cabin area. The flight crew simultaneously heard circuit breakers popping and cabin chimes sounding. The flight crew decided that at an immediate evacuation was necessary, and stopped the airplane. The order was given to the cabin crew to deploy the emergency slides and evacuate the passengers. All emergency slides were deployed; there were no injuries incurred during the evacuation. Maintenance personnel noted minor damage to the airplane as a result of a chaffed wire bundle in the mid-cargo pit ceiling at station 750 that had arced and produced smoke in the cabin area. The area was identified as a Boeing-designed and retrofitted over wing heater wiring installation. Engineers for the operator and manufacturer of the airplane determined that arcing was likely due to the left and right over wing heater blanket wiring, that contacted the edge of the wire bundle bracket that attached to the second inboard lighting hole at station 750 in the mid-cargo pit ceiling on the left side. They also determined that the vibration through normal airplane operation allowed the bracket to cut through the wire insulation and then contact was made to the wire conductor and arcing occurred. The operator inspected their entire fleet of affected airplanes and noted one other wire bundle discrepancy. The manufacturer of the airplane identified one other operator with a similar configuration. A service bulletin was issued identifying the problem and provided instructions on adjusting the wire bundles in order to prevent future occurrences.

Verbatim NTSB analysis and probable cause from the NTSB dataset