Boeing engineering and maintenance teams staged at locations around the world Friday began battery modifications to get airlines’ fleets of 787 Dreamliners, grounded since January, back in service.
Those “airplane on the ground” teams began their work as the Federal Aviation Administration Friday afternoon approved Boeing’s plan to improve the safety of lithium ion batteries aboard the 787 Dreamliners.
The FAA, and airline safety authorities around the world had grounded the twin-engine composite-bodied planes in mid-January after two incidents. In those incidents, 787 lithium batteries overheated and melted down, but caused no casualties to passengers or crew members.
Those new Boeing safety measures are designed to prevent those batteries aboard 787 aircraft from overheating and to protect the plane and its passengers in the event those batteries malfunction.
“Safety of the traveling public is our number one priority. These changes to the 787 battery will ensure the safety of the aircraft and its passengers,” said Transportation Secretary Ray LaHood.
The FAA’s order, however, falls short of a blanket approval of returning those aircraft to flight immediately.
That order lifting the grounding will likely come next week.
Foreign regulators, who followed the FAA lead in grounding the 787s, are expected to follow suit, allowing airlines owning and leasing the advanced twin-engine, composite-bodied jets to once again put them back in service.
Japanese regulators, however, may require further safety measures beyond what Boeing has proposed, reported one Japanese publication.
Before those planes, 50 at airlines around the world, can fly again, Boeing will install new batteries, software governing how and when they are recharged and a robust stainless steel containment battery box designed to keep any thermal overrun from damaging the aircraft or its electronics. That box includes a vent that will direct any fumes from an overheated battery to the atmosphere outside the plane.
The planes’ grounding is expected to cost Boeing more than $500 million. Part of that expense will go to compensate airline customers who had to cancel flights or lease other aircraft to handle flights originally assigned to 787s.
The modifications are expected to require about five days per plane, said Mike Sinnett, Boeing’s vice president and chief project engineer for the 787.
Boeing was shipping battery containment kits Friday and the Japanese maker of the batteries began shipping the modified batteries directly to the eight airlines involved.
The grounding has been the longest ordered by the FAA since 1979, when it grounded McDonnell Douglas DC-10 aircraft after an engine fell off a DC-10 just after takeoff from Chicago. That crash took the lives of 273 people.
The Dreamliner grounding was prompted by two January incidents, one in Boston and the other in Japan. In the Boston incident, a Japan Air Lines Dreamliner that had just completed a flight from Tokyo experienced a battery meltdown after passengers had left the plane. In the other incident, an All Nippon Airways on a domestic flight in Japan made an emergency landing after one of the plane’s lithium ion batteries overheated.
Boeing has redesigned the lithium ion batteries to put more separation between the battery cells to prevent a thermal runaway in one cell from spreading to another. Lithium ion batteries, relatively lightweight powerhouses, have been troublesome in multiple applications, in hybrid cars, in business aircraft and in computers.
In the Dreamliner, two lithium ion batteries are used as backups to provide emergency power for essential functions and instruments if the plane’s generators fail and to power start up of engines and other systems.
Boeing has also altered the software that controls the batteries’ charge and discharge cycles to ensure that the batteries aren’t subjected to destabilizing spikes of voltage.
Though three months have passed since the two battery incidents, neither the U.S. National Transportation Safety Board nor Japanese safety regulators has isolated the cause of the battery meltdowns.
Sinnett, in an afternoon briefing for reporters, said the company spent more than 100,000 person-hours testing the new battery protection scheme.
Those tests, which included deliberately heating the redesigned battery to failure levels showed the new design won’t create either the high heat or the long meltdown of the prior battery. Temperatures inside the battery enclosure with the new design peaked briefly at about 250 degrees versus 575 degrees with the earlier design. That temperature peak was short-lived, while the peak temperatures with the earlier battery were sustained for hours.
Sinnett declined to speculate when the first 787s would return to commercial service. Much of that depends, he said, on airline preferences and procedures.
While the 10-person AOG teams are installing the modified battery packages, they will also install several updates to bring the 787s up to the latest specifications. Among those updates are new power panels, modified generators and uprated hydraulic lines in several locations.