What happened
On 31 January 2011, during a scheduled passenger flight from Hong Kong to Singapore, a cabin crew member experienced a sudden loud bang while in a lavatory. This was immediately followed by the smell of electrical burning and the appearance of white smoke emitting from the wall panel beneath the sink. The crew member used a fire extinguisher to suppress the smoke, which eventually cleared. The Airbus A380-800, registration 9V-SKD, landed in Singapore without further incident, and there were no injuries among the 381 people on board.
The investigation
Post-landing inspections of the aircraft revealed damage in the forward cargo compartment, specifically at the feeder terminal block located beneath the affected lavatory. Investigators found soot on nearby components, melted cable lugs, and burnt insulation blankets. Further examination of the electrical system identified that the Main Excitation Cable was degraded, with visible damage to the shielding and the insulation of the negative wire caused by electrical arcing.
Findings
- The primary cause of the incident was a degraded Main Excitation Cable which allowed for electrical arcing between the negative wire and the cable shielding.
- This arcing created a short circuit that increased the voltage output of the No.1 Variable Frequency Generator (VFG) to 181Vac.
- Because the voltage on the negative wire remained high, the existing Fast Over-Voltage (FOV) protection logic failed to trigger.
- The excessive voltage caused the Lightning Protection Units (LPUs) to conduct for an extended period, leading to a short circuit between the feeder cables and the aircraft structure.
- This resulted in high levels of current that overheated the terminal block and LPUs, though the Over-Current protection eventually activated to limit the extent of the damage.
- The investigation also noted that the fire extinguisher discharged by the crew could not reach the actual site of the fire in the cargo compartment.