Background
During a trip check, airport customer service personnel reported to a mechanic that one of the center cargo bay longitudinal spring-lift power drive unit (PDU) powered rollers was inoperative and stuck in the 'up' position. The mechanic subsequently removed the powered rollers from the cargo compartment but did not have the McDonnell Douglas MD-11 Maintenance Manual available at the time. Additionally, the mechanic failed to open the circuit breaker for the cargo control unit (CCU) that governs the operation of the powered rollers, nor did he tag the system as out of service, as required by the maintenance manual.
Incident Details
While the mechanic was away from the aircraft to obtain a replacement powered roller, a crew change occurred among the airport customer service personnel. The new crew, unaware that the cannon plug from the powered roller had been left on the cargo compartment floor, began loading cargo bins. During loading, the cargo bins ran over the cannon plug, cutting its connecting wires.
Fire and Response
A Delta technician started the aircraft's auxiliary power unit (APU) to supply electrical power. Other Delta technicians servicing the cabin observed smoke and flames measuring 4 to 6 inches emanating from behind a floor vent in the main passenger cabin near row 12. The fire was subsequently extinguished. The incident highlights the importance of adhering to maintenance procedures.