Latest reports from the inquiries into the grounding of Boeing’s new generation Dreamliner aircraft have thrown up differing reasons for electrical malfunctions.
The US National Transportation Safety Board revealed at the weekend that the lithium battery that caught fire on a parked Japan Airlines 787 earlier this month "did not exceed its designed voltage."
Meanwhile, Japanese investigators looking into the cause of a second lithium-ion battery malfunction aboard an ANA 787, which occurred a little more than a week later, have indicated the battery in that incident may have been overcharged, leading to an emergency landing after pilots noticed a burning smell.
The safety board's update suggests different circumstances may have preceded the two incidents and that at least to some extent, the investigations surprisingly may be headed in divergent directions.
If that is the case, it may complicate efforts to determine the root cause of the two incidents and potentially delay Boeing's effort to persuade regulators to allow the planes back into service.
The world-wide grounding of Boeing 787s has entered its sixth day, with 50 airfracft flown by more than half a dozen airlines involved.
The US Federal Aviation Administration last week said both batteries leaked electrolyte fluid and resulted in smoke damage to nearby portions of the aircraft.
US and Japanese safety experts have been working together and sharing preliminary information, though their investigations are being run separately. FAA officials are waiting for more data and analysis before agreeing on interim safeguards to allow 787 Dreamliners back in the air.
The FAA-imposed grounding notice also prohibts Boeing from conducting test flights of yet-to-be-delivered 787s. Boeing has formally announced a moratorium on Dreamliner deliveries.