British air investigators say 787 fire originated in locator batteries

LONDON (WCIV) -- The British air investigations agency looking into the Ethiopian Air-branded 787 that caught fire at London's Heathrow Airport said Thursday the fire appears to have originated in a set of emergency locator batteries.

The batteries are made by Honeywell, according to documents from the Air Accidents Investigation Branch.

The AAIB said during a technical investigation after the July 12 fire, crews were able to trace the fire back to wiring linked to the 787's Emergency Locator Transmitter, a system that is designed to be always on and operate independently of the plane's electrical system in the event of an emergency.

The batteries are made of Lithium-Manganese Dioxide, the AAIB reported. The batteries are cable of initiating a fire from stored energy in the chemical cells.

During the examination, AAIB investigators found evidence that there had been a disruption to the battery cells. The investigators were not able to determine whether the fire was triggered by the batteries or an external source.

"In the case of an electrical short, the same batteries could provide the energy for an ignition and suffer damage in the subsequent fire," the report reads.

Honeywell has manufactured 6,000 similar batteries to fit a variety of aircraft; the July 12 incident was the only significant fire ever reported, the AAIB reported, making a similar thermal event very rare.{}

"There has been no incident that Honeywell has identified. There has really been no problem with these type of transmitters," said Jon Ostrower, and aerospace reporter for the Wall Street Journal. "They've operated trouble-free for years, certified in 2005 and there really hasn't been an issue."

"However, large transport aircraft do not typically carry the means of fire detection or suppression in the space above the cabin ceilings," the report continues. "And had this event occurred in flight, it could pose a significant safety concern."

The AAIB made two recommendations. First, it advised the Federal Aviation Administration take action to remove the Honeywell batteries from Boeing 787s until they are deemed safe. It also advised the FAA to conduct a comprehensive safety investigation of ELTs in other aircraft.

Honeywell issued a statement Thursday after the findings were released, saying it will be providing any assistance Boeing needs.

"The investigation continues, and it's premature to jump to conclusions.{} Temporarily addressing the ELTs on Boeing 787s as a precautionary measure is prudent. The Boeing 787 ELT product action is a straightforward process, and we do not anticipate any material financial impact to Honeywell. We also support conducting safety reviews for installations of any lithium battery-powered ELTs from the variety of manufacturers who sell them," a company spokesman said.

Boeing referred requests for comment to the AAIB, saying the company was not able to comment on the report.

These are not the same batteries that led to the FAA's grounding of the 787 fleet in January. Fifty Dreamliners worldwide were grounded at that time because of battery malfunctions. Boeing later modified the jets with new batteries.

In April, an Ethiopian Airlines Dreamliner made the first commercial flight since the grounding.

Ostrower said in the short term, the incident will not have an effect on manufacturing in the Lowcountry.

"Certainly what comes out of the investigation will inform how Boeing feels about the designs of these sorts of beacons, what other things are around them," he said.

Cabin filled with smoke

The AAIB reports says firefighters had to enter the aircraft to battle the fire because foam sprays on the outside of the aircraft were not working to extinguish the fire.

When firefighters entered the Boeing aircraft, they found a cabin filled with smoke. There was evidence of fire above the ceiling panels.

A handheld Halon extinguisher was ineffective against the fire, but water hoses were able to quickly put out the small blaze.

Before the first signs of fire were noticed, crew members aboard the previous flights did not log any anomalies, the report states. A ground crew went through the process of disconnecting the plane from the power source at the airport.

That was at 5:40 a.m. July 12.

Ten hours later, an employee in the air tower spotted smoke coming from the 787 and notified Heathrow's fire department.