Coatings Blamed for Aircraft Fuel Leak
Flawed coatings are responsible for a fuel leak in Boeing’s 787 Dreamliner aircraft, investigators in Japan have determined after a slew of problems have grounded the planes worldwide.
A fuel leak in a Japan Airlines Boeing 787 Dreamliner during maintenance work was due to a malfunction in the valve of a fuel pipe caused by a problem with the coatings, Japan's Land, Infrastructure, Transport and Tourism Ministry (MLIT) said on Friday (Feb. 22).
The ministry launched an investigation after two fuel leaks occured on a Dreamliner operated by Japan Airlines Co. Ltd. just days before the plane was grounded around the world following several battery problems.
2 Fuel Leaks
As maintenance engineers removed fuel from a 787 at Narita International Airport on Jan. 13, about 100 liters of jet fuel leaked from the valve. An indicator in the cockpit showed the valve was closed when it was actually open.
The same aircraft had leaked fuel at Boston's Logan International Airport on Jan. 9, and an investigation found that a foreign substance stuck in the fuel tank caused a different valve to fail.
Japan's Transport Ministry said it believed there were deficiencies in the way electrical-insulating coatings were applied during the manufacturing process to the mechanism that opens and closes the fuel tank valve.
"The problem of fuel leaks has been cleared up," said Akihiro Ohta, minister of MLIT.
The ministry's air safety regulators instructed Japan Airlines and All Nippon Airways Co. to conduct more rigorous valve checks each time the aircraft flies or during inspections. Both carriers said they had received the instructions, but declined to comment further, The Wall Street Journal reported.
Officials said the manufacturer of the valve equipment already revised the production process.
Unresolved Battery Issue
The Boeing 787 jets have been grounded worldwide after one of the planes made an emergency landing in January because of smoke in the cockpit, leading to probes into the electrical system, particularly the lithium-ion batteries.
Japanese authorities still have not determined the cause of the battery issue.
Last week, United Continental Holdings said it was taking the Dreamliner out of its flying plans through June 5, except for a Denver-to-Tokyo route scheduled for May. The route was originally scheduled to start March 31.
United is the only U.S. carrier currently operating the 787 and has six of the planes.
Boeing calls the aircraft the "world's most advanced family of jetliners."
Boeing, FAA DIscuss Issues
Boeing released a statement earlier in February, saying it welcomed the progress reported by the U.S. National Transportation Safety Board in the 787 investigation, including the identified battery problems.
"We are working collaboratively to address questions about our testing and compliance with certification standards, and we will not hesitate to make changes that lead to improved testing processes and products," the statement said.
|Dave Sizer / Wikimedia Commons|
All Boeing 787s have been grounded worldwide after problems with the lithium-ion batteries caused smoke to fill the cockpit of one plane. The battery problem is unrelated to the fuel valve issue, officials said.
On Friday (Feb. 22), the U.S. Federal Aviation Administration said that Deputy Transportation Secretary John Porcari, FAA Administrator Michael P. Huerta, and other FAA officials met with senior executives from Boeing to discuss the 787 battery issues.
The FAA is reviewing a Boeing proposal and "won't allow the 787 to return to commercial service until we're confident that any proposed solution has addressed the battery failure risks."
The plane has two primary rechargeable batteries—the main and auxiliary power unit (APU). The batteries serve separate purposes: the main battery powers the aircraft before the engines have started, supports ground operations like refueling and powering the brake system when the airplane is towed, and provides backup power in the event of a power failure; the APU battery supplies the power to start the airplane engines.
Both batteries are lithium-ion, which Boeing says can deliver a large amount of power in a short period of time and can recharge in a relatively short period of time.
The batteries for the 787s each have eight cells and have logged more than 2.2 million cell-hours on the ground and 50,000 in-air flight hours, according to Boeing. Before January 2013, no battery-related incidents had occurred.