F.A.A. Orders Airlines to Inspect Transmitter Wiring

Safety investigators are examining whether a pinched wire on a harness connecting a battery to the transmitter caused or helped spread the fire. They also want to check the transmitters’ battery for signs of unusual heating or moisture.

While the agency prepares the order over the next few days, Boeing plans to instruct all 13 airlines that use the Dreamliner to either inspect or remove the transmitters, which send out a plane’s location after a crash.

The F.A.A.’s plans to order only an inspection fall short of a recommendation on Thursday by British investigators, who called on the F.A.A. to order airlines to disable the batteries. It also might place the F.A.A. in conflict with other regulators. Air Transport World, a trade publication, on Friday quoted a spokesman for the European Aviation Safety Agency as saying that it was drafting instructions to European airlines to remove the transmitters.

The British Air Accidents Investigation Branch also called on Thursday for a broader safety review of similar devices in thousands of other jets. But the F.A.A. will take more time to review the recommendation.

Reuters reported on Friday that Japanese authorities planned to temporarily waive rules that require its airlines to have transmitters on their planes. That action would allow All Nippon Airways and Japan Airlines, which fly more than 40 percent of the 68 Dreamliners delivered so far, to remove the devices if they saw fit.

Boeing and regulators from the United States, Europe and Japan have been trying to devise a solution that would work even if various countries differ on whether the devices should be removed or merely inspected.

The British investigators made their recommendations after finding signs of disruption in the battery cells of an emergency transmitter on an Ethiopian Airlines 787 that caught fire while parked at Heathrow Airport. The British said the investigation was still in its early stages, and the cause had not been established.

British investigators called for quick action to address the problem because most passenger jets do not have fire suppressant systems near the transmitters, which are attached to the top of the plane just in front of the tail. That area received the most damage from the fire on the Ethiopian Airlines 787, which had been parked at Heathrow for 10 hours.

If such a fire occurred in flight, the British investigators said on Thursday, “it could pose a significant safety concern and raise challenges for the cabin crew.”

The Dreamliner, which makes extensive use of lightweight composite materials and cuts fuel costs by 20 percent, is crucial to Boeing’s future.

United States officials have said that the lack of proof about the cause of the fire — and the fact that none of the transmitters had been known to cause a fire in more than 50 million flight hours — suggested that simply inspecting, rather than removing, the devices should be sufficient.

In its report on Thursday, Britain’s Air Accidents Investigation Branch said that about 6,000 of the transmitters had been produced by Honeywell Aerospace since 2005. The transmitters are used in a wide range of aircraft, including Airbus planes. Honeywell and other manufacturers also make similar devices for thousands of other commercial and business jets.

Aviation experts said the devices have been particularly helpful in locating the wreckage of smaller private and corporate planes. The global positioning and communications systems on the 787 and other large jets are so sophisticated that they constantly relay the planes’ locations to computers on the ground, making the devices less critical.

Given the possibility of malfunction, Boeing and Honeywell have each said it would be prudent for airlines to temporarily remove the devices from 787s while the investigation into the cause of the fire continues.

In looking for signs of unusual heating or moisture in the transmitter’s battery, investigators are also considering whether distinctive characteristics of the 787 could have played a role.

The 787’s cabin maintains a higher humidity level than other jets to increase passenger comfort. One theory is that the humidity could have created condensation that caused a short circuit in the battery or its wiring.

Another concern is that the composite skin absorbs more heat from the sun than the aluminum on other planes. That has prompted questions about whether the battery in the transmitter could have been degraded by excessive heat from the skin.

But battery experts said that barring a flaw in the battery’s construction, the transmitter is sealed so tightly that neither moisture nor heat was likely to cause a short circuit. “I can’t really subscribe to either one of those,” said Ralph J. Brodd, a battery consultant in Henderson, Nev.

Article source: http://www.nytimes.com/2013/07/20/business/boeing-787-inquiry-zeroes-in-on-transmitters-wire.html?partner=rss&emc=rss