| NEW YORK, June 18
NEW YORK, June 18 A fire that scorched the top
of a Boeing Co 787 Dreamliner at London Heathrow airport
last summer was likely caused by faulty wiring in an emergency
rescue beacon that led to "an uncontrolled discharge" from a
lithium-ion battery, the UK aviation safety agency said on
The battery likely discharged unevenly, causing one of its
cells to deplete more than the other four, then reverse polarity
and absorb energy from the others, the UK Air Accidents
Investigation Branch (AAIB) said in a special report.
"Several tests demonstrated that when a cell failed in this
manner, the heat released caused the failure to cascade to the
remaining four cells," the AAIB said.
Honeywell said it appreciated the AAIB's throughness and
noted it had worked with the Federal Aviation Administration and
Transport Canada on an airworthiness directive requiring "that
all applicable ELT units are inspected to verify that the error
is not present." It added, "Honeywell is committed to ensuring
the safety of all its products and has implemented a redesign
and amended assembly/installation guidelines for this product."
The July 12, 2013, fire in the emergency locator transmitter
(ELT), made by Honeywell International Inc, burned the
top of the fuselage of the Ethiopian Airlines jet,
taking it out of service for an extended period and renewing
concern about use of lithium-based batteries on aircraft. No one
was injured in the incident and the jet was parked at the time.
Separately, the global fleet of Dreamliners was grounded for
three months last year after two other lithium-ion batteries,
not related to the ELT, burned in two incidents in Japan and the
No one was injured in those incidents, but out of concern
for safety, regulators halted flights while Boeing redesigned
the batteries and the charging system, and created a steel box
to contain a fire.
(Editing by Jonathan Oatis)