Root cause of Boeing battery problems to remain unknown

Engineers unable to pinpoint exact cause out of 80 possibilities

Boeing has admitted that it may never know the exact cause of the problems with the lithium-ion batteries on its 787 Dreamliner.

The US government grounded the 787 earlier this year when faults with the batteries caused one fire and forced another plane to make an emergency landing.

Boeing said it had identified 80 possible causes for the battery problems when it announced the fix last month. The American aviation authority, the FAA, has approved improvements to the battery’s design and testing, which includes new enclosures, insulation, operating parameters and four additional tests.

However, at a press briefing in London today, Boeing's 787 programme vice president and general manager Larry Loftis said: "It is possible we may never know the root cause (of the battery failure)."

He added that Boeing was confident the improvement work would ensure the absolute safety of the aircraft. Loftis could not give an exact date when airlines would get their delayed planes but confirmed that Boeing was having "detailed conversations" with airlines and that planes could be delivered "within weeks".

The first UK airline which plans to fly the 787 is holiday firm Thomson. Flights were originally planned to commence during May. Both British Airways and Virgin have ordered the aircraft. The 787 can seat between 210 and 290 passengers on medium-range routes.