The FAA made no mention Friday of disabling the transmitters in a brief statement provided to the media. Instead, the agency said that after reviewing the British investigators' recommendations, U.S. officials have begun working with Boeing to develop instructions for how airlines should conduct the inspections.
The inspections would ask airlines to examine transmitters for proper wire routing and damaged or pinched wires, the statement said. The transmitter's lithium battery compartment would be inspected for heat or moisture.
An order making the inspections mandatory for U.S. operators is expected in the coming days, the FAA said.
FAA safety orders apply only to operators of U.S. registered planes, but aviation authorities in other countries are expected to follow with their own orders for inspecting or disabling the transmitters.
Boeing has delivered 68 of the planes worldwide so far, all with the same transmitter made by Honeywell International Inc. United Airlines is the only U.S. operator of the planes, with six.
Britain's Thomson Airways, which has six 787s, said on Thursday that it had already removed the emergency locator transmitters from its 787s. It said its 787 flights would still operate as planned. "This is not a Boeing 787 technical issue," the airline said, but an issue with the transmitter made by Honeywell.
As Honeywell reported financial results on Friday, an analyst asked CEO David Cote how it would be possible for such a relatively small transmitter to cause a fire like the one in the 787 at Heathrow. Cote didn't answer directly, but said he wants to wait and see what the final investigation finds.
"We'll just wait to find out what actuals are, and respond to it then," he said. "There's no significant financial impact to Honeywell in any way."
British investigators have said it is not clear if the fire was caused by the transmitter's lithium-manganese dioxide batteries or a short near or around the transmitter. A spokeswoman for the investigative branch said the easiest way to make the transmitter systems "inert" — as set out in their recommendations — would be to take out their batteries.
Honeywell has made 6,000 of these transmitters and they're used in a wide range of planes. The actions announced by the FAA, however, apply only to 787s.
The transmitters have logged 50 million hours of flight on planes other than the 787 with few reports of incidents, and none as serious as the London fire, an official familiar with the transmitters' history said. The official, who wasn't authorized to speak publicly, asked not to be named.
The locators are activated in a crash and send a signal that satellites use to calculate the location of the plane. They're most helpful when a plane crashes in a remote area on land, making it difficult for rescuers to find the wreckage. They're of little value in accidents where a plane is underwater or where the location of the plane is clear, such as the crash landing of an Asiana Airlines plane at San Francisco International Airport two weeks ago.
The 787 is Boeing's newest and most technologically advanced plane. It's the first airliner with a skin made mostly of lightweight composite materials. It relies far more than other airliners on electrical systems to operate. And it is the first airliner to make extensive use of rechargeable lithium ion batteries.
The plane is key to Boeing's future, but it has been plagued with problems. The entire 787 fleet was grounded for about three months earlier this year after a fire in a battery unrelated to the transmitter on a Japan Airlines 787 parked at Boston's Logan International Airport, and another smoking battery that led to an emergency landing by an All Nippon Airways 787 in Japan.
U.S. and Japanese authorities are still investigating the two incidents, but have reached no conclusion on the cause of the battery failures.
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