Exclusive: Probe of Boeing's 787 focuses on condensation, emergency beacon

Fri Jul 19, 2013 6:38pm EDT
 
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By Andrea Shalal-Esa and Alwyn Scott

WASHINGTON/SEATTLE (Reuters) - Officials investigating the fire on a parked Ethiopian Airlines Boeing 787 are focused on how condensation and increased humidity could have sparked the blaze at London's Heathrow Airport last week, three sources familiar with the probe said.

British authorities said on Thursday an emergency beacon made by Honeywell International Inc was the likely source of the fire, and called for the device to be turned off. But the UK Air Accidents Investigation Branch (AAIB) said it was still trying to understand what sparked the fire.

The U.S. Federal Aviation Administration is close to taking steps to follow the AAIB recommendations.

The July 12 fire rekindled concerns in the industry about Boeing Co's advanced carbon-composite Dreamliner, which was grounded for more three months earlier this year after two incidents involving overheated lithium-ion batteries. The AAIB said the London fire is not related to those batteries.

Investigators are still trying to determine if condensation on the plane may have seeped into the Honeywell emergency locator transmitter (ELT), triggering a short circuit in the unit's battery, which is made by Ultralife Corp, according to the sources, who were not authorized to speak publicly because the probe is still ongoing.

Condensation is normal on big airliners, but the 787 has a higher level of humidity to make passengers more comfortable. The Dreamliner is pressurized at about 6,000 feet, compared to 8,000 for most other airliners.

Water conducts electricity, so high moisture levels could raise the likelihood of short circuits. Long term exposure to moisture can cause corrosion on electrical wires and batteries.

The 787 carries humidity controls made by CTT Systems AB of Sweden. The company had no immediate comment. CTT's website said its system controls condensation on aircraft, including the 787, and is in use on other aircraft.   Continued...

 
Emergency services attend to a Boeing 787 Dreamliner, operated by Ethiopian Airlines, after it caught fire at Britain's Heathrow airport in west London July 12, 2013. REUTERS/Toby Melville