Synopsis
On 30 October 2013 at about 2120 hours, a Singapore Airlines Airbus A380 (registration 9V-SKB) was operating a scheduled passenger flight from Singapore Changi Airport to Sydney, Australia. While climbing through flight level 130, a leading stewardess noticed a wisp of smoke from the area around seat 55D. Upon investigation, she observed sparks coming from behind the IFE screen and a puff of thicker smoke. She instructed the passenger to move away, retrieved a halon fire extinguisher from an overhead compartment, and discharged it at the screen. The inflight supervisor arrived and toggled off the electrical isolation switch under the cushion of seat 54D, intended to remove power to the IFE system for row 54. However, for about 15 minutes thereafter, the light at the base of the screen continued flickering and the handset remained lit. No recurrence of smoke or sparks occurred, and the flight proceeded to Sydney without further incident. There were no injuries.
Aircraft and System Details
The aircraft was an Airbus A380-800 equipped with four Rolls-Royce Trent 800 engines. The IFE system at seat 55D consisted of a display unit mounted on the rear face of seat 54D, a handset, and a cradle. Four IFE units on row 54DEFG were powered in common via a supply power module, a seat electronic box, and an electrical isolation switch under the cushion of seat 54D. The switch controlled power to the entire row; a wire harness connected the switch to each display unit.
Investigation Findings
Components examined by the IFE manufacturer revealed signs of heat stress on an integrated circuit chip (IC500), a ferrite bead (FB1), and the printed circuit board beneath IC500 on the display unit from seat 54D. The chip manufacturer determined the failure was due to electrical overstress. Further tests suggested the overstress could have been caused by an overvoltage or overcurrent applied to a pin providing USB functionality. The passenger at seat 55D was not using the IFE system at the time, and no devices were plugged into the USB port.
The investigation also found that the wire harness connecting the electrical isolation switch to the supply power module was severed. This meant toggling the switch did not actually cut power to the display unit, explaining why the light and handset remained active after the switch was turned off. The severed wire likely occurred during installation of the seat assembly when the aircraft was prepared for delivery; the harness may have been pinched between the seat assembly and floor panel. The maintenance manual contained no instruction for a functional check of the isolation switch after maintenance, which could have detected the damage.
Analysis
The overvoltage or overcurrent condition generated heat, damaging the IC500 chip and surrounding components, leading to sparks and smoke. The exact cause of the overvoltage or overcurrent could not be determined. The continual power supply after the switch was toggled was due to the severed wire harness, preventing isolation of power.