What happened
Flight crewmembers of the jumbo jet were preparing to start the engines when flight attendants in the forward cabin detected a faint odor before closing door 1L. Because the source of the smell could not be determined, the door was closed in preparation for pushback. Shortly thereafter, smoke was discovered in the vicinity of the overhead bin at row 16. The captain was notified and ordered that occupants evacuate if there was a fire onboard.
The jetway was brought back to door 1L. The smoke dissipated; thus, the flight attendants at doors 1R, 2L, and 2R did not open their doors. However, the flight attendants at the other six doors were unaware of the situation and continued the evacuation. The ramps at doors 3L and 3R did not inflate, and door 5R jammed halfway open.
The investigation
An examination revealed that the ramp packs for doors 3R and 3L were improperly mounted. The pack board for door 5R was made for a left-hand door, and the lanyard was not connected to the bottom panel pulley. An exam revealed a ballast for an overhead fluorescent light, PN 69-33C, had overheated and melted the plastic case.
Findings
Contributing factors included the improper installation of evacuation equipment on multiple doors and the failure of an electrical component. The ballast for an overhead fluorescent light overheated, melting its plastic case and generating smoke within the cabin.