An airport worker approaches a Japan Airlines Boeing 787 at Boston's Logan Airport in July 2013. The plane's flight to Tokyo returned to Boston because of a possible fuel pump issue, the latest trouble for the aircraft that also had battery problems. / Elise Amendola, AP
More and better tests should be performed on the batteries aboard Boeing's 787 Dreamliners to avoid the smoky overheating aboard two planes that grounded the fleet last year, safety officials told the Federal Aviation Administration on Thursday.
The National Transportation Safety Board made five recommendations to the FAA for testing lithium-ion batteries and consulting more with experts about what could go wrong aboard planes with the new technology.
"The NTSB is vitally interested in these recommendations because they are designed to prevent accidents and save lives," said the 12-page letter from board members Christopher Hart, Robert Sumwalt, Mark Rosekind and Earl Weener.
The FAA issued a statement saying it will review the NTSB recommendations, but that it is already working closely with battery experts and foreign aviation authorities to update standards for lithium-ion batteries on planes. The agency said it has considered safety issues for batteries and for the entire plane.
"The FAA expects the new standards will provide a compliance road map for manufacturers to show compliance to FAA special-condition requirements for all lithium battery sizes," the agency said.
Marc Birtel, a Boeing spokesman, said certification tests for the 787 complied with widely accepted industry standards and that the company would work with FAA as standards evolve. He said testing before the Dreamliner returned to service last year was consistent with NTSB's recommendations, which a board spokesman confirmed.
"We therefore remain confident in the safety and integrity of the comprehensive battery solution which was developed by Boeing, and approved by the FAA, last year," Birtel said.
Hart, the acting board chairman, said emerging technologies play a key role in improving flight safety.
"This is why it's crucial that the process by which these technologies are evaluated and certified is as robust and thorough as possible," Hart said.
NTSB and the FAA each continue to investigate what the safety board described as "heavy smoke" and "small flames" in a lithium-ion battery aboard a Japan Airlines plane parked at Boston's Logan airport in January 2013.
Nine days later, a smoldering battery forced an All Nippon Airways flight to make an emergency landing in Japan. Nobody was injured in either incident, but the FAA grounded the fleet for more than three months while studying what went wrong.
The battery problem tarnished the introduction of the innovative aircraft, which is made from composites and 20% more fuel efficient than comparably sized planes. Boeing had delivered 50 Dreamliners worldwide when the fleet was grounded, including six to United Airlines.
There were 143 Dreamliners in service worldwide by May 7, according to Flightglobal's Ascend Online Fleets database. All Nippon Airways has the most with 27. Japan Airlines has 15, Air Indian 13, Qatar Airways 13 and United 10.
After the incidents, Boeing and the FAA took steps to prevent batteries from overheating before the aircraft returned to the sky without knowing exactly why the batteries failed.
Boeing installed more insulation between each battery's cells and a fireproof shell around the battery to starve it of oxygen if there is a fire. Each battery now has a titanium venting tube to a hole in the fuselage to carry flammable electrolytes and smoke overboard if a battery fails.
In March, FAA Administrator Michael Huerta concluded a year-long review of the Dreamliner's overall certification by reiterating that "the aircraft is safe and that it meets its intended level of design and safety."
Boeing Commercial Airplanes CEO Ray Conner said the findings validated the company's confidence in the plane and the process of correcting problems when they arise.
But the NTSB found that to get the plane certified, Boeing tested the batteries by driving a nail into the side of one rather than provoking an internal short-circuit through overheating or other abuse.
Investigators found electrical arcing about the Boston battery and excessive current flowing between the battery and charger before it overheated and went out of control in what is called a "thermal runaway."
"However, Boeing underestimated the more serious effects of an internal short-circuit," the NTSB said.
Boeing chose rechargeable lithium batteries for the plane because they are smaller and pack more power than competitors, which is why they're also used in phones and laptops. But because their power is packed more tightly, they are susceptible to overheating. A lithium-ion battery provides 150 watt-hours per kilogram, compared with a nickel-metal hydride (100) and lead-acid like a standard car battery (50).
Each Dreamliner has two of the batteries. The main one in front powers aircraft electronics to bring the plane to life before starting the engines, which are then run by generators. The main battery also powers ground operations such as refueling and powering brakes while being towed, and can act as a backup if there is a power failure during flight. The second battery toward the back of the plane serves the auxiliary-power unit that can start the engines and serves as another backup.
The board said its findings were urgent enough to recommend that the FAA:
â?¢ Develop tests to short-circuit one of the eight cells in a battery aboard a plane to see whether a thermal runaway spreads.
â?¢ Require Boeing and other manufacturers to conduct the tests on any permanently installed lithium-ion batteries aboard planes.
â?¢ Work with experts to develop standards for testing batteries.
â?¢ Review the methods that certified batteries on planes and possibly require more testing.
â?¢ Create a panel of independent technical experts to advise the FAA on certifying new technology.
The NTSB asked the FAA to respond to the recommendations within 90 days.
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