DALLAS (AP) — The battery that caught fire in the Japan Airlines 787 Dreamliner in Boston was not overcharged, but government investigators said Sunday there could still be problems with wiring or other charging components.
An examination of the flight data recorder indicated that the battery didn’t exceed its designed voltage of 32 volts, the National Transportation Safety Board said in a statement.
But NTSB investigators are continuing to look at the battery system. They plan to meet Tuesday with officials from Securaplane Technologies Inc., manufacturer of the charger for the 787’s lithium ion batteries, at the company’s headquarters in Tucson, Ariz., said Kelly Nantel, a spokeswoman for the board.
“Potentially there could be some other charging issue,” Ms. Nantel said. “We’re not prepared to say there was no charging issue.”
Even though it appears the voltage limit wasn’t exceeded in the case of the battery that caught fire on the 787 in Boston, it’s possible that the battery failures may be due to a charging problem, according to John Goglia, a former NTSB board member and aviation safety expert.
Too much current flowing too fast into a battery can overwhelm the battery, causing it to short-circuit and overheat even if the battery’s voltage remains within its design limit, he said.
“The battery is like a big sponge,” Mr. Goglia said. “You can feed it with an eye dropper or you can feed it with a garden hose. If allowed, it will soak up everything it can from the garden hose until it destroys itself.”
There are so many redundancies and safeguards in aviation that when an accident or mishap occurs, it almost always is the result of a chain of events rather than a single failure, he said.
The batteries in two incidents “had a thermal overrun because they short-circuited,” he said. “The question is whether it was a manufacturing flaw in the battery or whether it was induced by battery charging.”
The unfolding saga of Boeing’s highest-profile plane has raised new questions about federal oversight of aircraft makers and airlines. After the two separate and serious battery problems, it wasn’t U.S. authorities who acted first to ground the plane — it was Japanese airlines.
Some aviation experts question the ability of the Federal Aviation Administration to keep up with changes in the way planes are being made today — both the technological advances and the use of multiple suppliers from around the globe. Others question whether regulators are too cozy with aircraft manufacturers.
Even as they announced a broad review of the 787 earlier this month, top U.S. transportation regulators stood side by side with a Boeing executive and declared the plane safe — saying that they would gladly fly in one. Transportation Secretary Ray LaHood repeated his endorsement Wednesday.
A few hours later, the FAA issued an emergency order grounding the planes.
Despite their concerns, many safety experts still believe that the current regulatory process works. The 787s were grounded before any accidents occurred.
The Dreamliner is the first airliner whose structure is made mostly from composite materials rather than aluminum. The plane relies more than previous airliners on electrical systems rather than hydraulic or mechanical ones, and it’s the first airliner to make extensive use of lithium-ion batteries to power cabin pressurization and other key functions.