Aviation Investigation Report A98H0003

1.12.4  Examination of Flight Crew Reading Lights (Map Lights) (STI1-65)

The first officer's map light was recovered and examined for electrical arc or heat damage and none was present. The light bulb was still attached to the lamp socket. The lamp filament had fractured into many pieces, indicative of the filament being cold, or off, at the time of impact. Typically, when an incandescent filament is severely impacted while illuminated, it will stretch in a characteristic fashion.

Portions of the right observer's map light, including the ball cup, were recovered and examined. There was no sign of arcing or heat damage; however, the majority of the electrical contact parts were missing. The aluminum housing in which the light was mounted had some soot accumulation on the outer surface but was not heat damaged. Two short lengths of wire, white and red, were visible inside the housing. The white wire exhibited a mechanical fracture; neither wire exhibited evidence of arcing or heat damage. The light bulb was not recovered.

Several pieces of Hella map light were recovered and examined. Because the internal components of the map light and bunk lights are identical, it was not possible to determine to which light these pieces belonged. None of these pieces showed signs of arcing or heat damage.

Two ball cups were also recovered. Based on the physical damage and extent of sooting, they were considered to have been from either the captain's or first officer's map light.

See Section 1.16.2 for additional details regarding map light investigation research and testing, and Section 4.1.4 for follow-up safety actions taken.

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