Saturday, February 14, 2009

Investigators in Ireland have found wiring problems in several Virgin Atlantic Airbus A340s as part of their investigation into a fire on board one such aircraft that was forced to divert to Shannon Airport.

The Virgin jet was headed from London Heathrow Airport to Chicago with 143 passengers and thirteen crew on January 11 this year. A small fire was noticed in a waste bin storage area in the first class section’s bar unit.

A damaged wiring loom could be seen sticking out of a hole in the compartments floor, and there was visible electrical arcing in the area. An attempt was made to control the situation by switching off electrical circuits, but both the fire and the arcing continued unchecked.

The aircraft’s captain declared an emergency and diverted to Shannon, which the airliner reached thirty minutes later. During that time, the crew used five 1kg fire extinguishers upon the fire, but each time the arcing continued and after about five minutes the fire reignited. Witnesses described the fire as consisting of “licks of flame”.

After performing a safe emergency landing the airport’s Aircraft Rescue and Firefighting department tackled the fire with a 5kg extinguisher but met with similar results. After consulting with the crew the jet’s power was completely shut down, after which the fire was finally put out. Virgin initially claimed the fire had never occurred.

Investigators with Ireland’s Air Accident Investigation Unit (AAIU) inspected the loom and found it to be “completely severed” and exhibiting “strong evidence of burning/arcing” according to a preliminary report released on Friday. The loom was identified as providing power and dimming circuits for mood lighting in the bar.

The AAIU says that it seems the loom had contacted the metal waste bin in the compartment above. There should have been rails to hold up the bin and a protective metal cover, but “no evidence” of these was found and the report notes that “Initial inspection indicated the possibility that they were never fitted.”

The bar unit is a modification exclusive to Virgin. The AAIU ordered all 36 of the airline’s A340s worldwide inspected, with both France and the United Kingdom assisting with this. The UK has identified four other aircraft with faulty wiring, it has now been revealed. Virgin says that “A few minor issues were found and were immediately rectified,” and adds that “The installation of the bar was carried out in accordance with all relevant regulations. Virgin Atlantic continues to assist the AAIU in their investigation and looks forward to the full report with interest.”

The AAIU says that “significant other issues are being examined by the investigation” in addition to the wiring defects. “These include the difficulties faced by the crew in isolating the damaged circuits, the emergency checklist, the design of the modification and the standards relating to such modifications,” said the report.

Virgin’s Boeing 747-400 fleet also has a similar bar installed on it, but there was not considered to be a risk to the aircraft’s wiring on that model. The fire involved a bar added three years ago, with the aircraft manufactured in 1998.