The Boeing 787 Dreamliner investigation continues as officials shift focus away from the lithium-ion batteries involved and towards the monitoring systems used on the Boeing 787.

The culprit appeared to be the Dreamliner's lithium-ion batteries. Photos of burned 787 batteries released in the wake of the aircraft's grounding seemed to vindicate those who said the energy-dense storage devices were not yet fit for flight.

But the US National Transportation Safety Board announced Sunday "no significant findings" in its initial investigation into the January battery fire at Logan International Airport in Boston.

Japan transport ministry official Shigeru Takano said Monday the government had ended its on-site investigation of GS Yuasa, the Dreamliner's batterymaker. Having found "no major quality or technical problem," ministry officials said they would shift the focus of their probe onto Kanagawa Prefecture-based Kanto Aircraft Instrument Co., which makes the system that monitors the lithium-ion batteries.

What, then, is wrong with the Dreamliner?

"I think people had their fingers crossed that it was a battery fault," Keith Hayward, head of research at the Royal Aeronautical Society, told BBC. "It looks more systemic and serious to me. I suspect it could be difficult to identify the cause."

Kanto Aircraft, which makes flight-data recorders and other aircraft electrical systems, has yet to comment publicly on the investigation. The Wall Street Journal reported Monday that the company had never developed a battery-monitoring system until GS Yuasa contracted it to do so for the Dreamliner battery.

Some say Boeing's disparate outsourcing should take the ultimate blame for the 787's glitches. In a candid speech in January 2011 at Seattle University, Boeing Commercial Airplanes chief Jim Albaugh blamed the 787's then problematic delays and additional costs on Boeing's global outsourcing strategy, aimed at reducing costs, according to the Seattle Times.

"We spent a lot more money in trying to recover than we ever would have spent if we'd tried to keep the key technologies closer to home," Mr. Albaugh said.

A Forbes article reported that the 787 has significantly more foreign-made content than any other Boeing plane.

"An unusually high level of subcontracted manufacturing has made it more difficult to track down the jets’ problem," the Forbes article concluded, "and an overly complex – and sometimes patchy – safety net could have contributed to it happening in the first place."

The 787's permitting process has also been called into question, with some saying the plane was given the green light despite concerns over the safety of a lithium-ion battery.

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In 2008, Japan's government eased safety regulations on the plane's Japanese technology in an effort to fast-track the plane's debut, according to Reuters, although there is no evidence linking the easing of the standards to January's battery fires.

RTCA Inc., a nonprofit organization that advises the FAA on technical issues, called for stricter testing to prevent battery fires after the FAA issued lithium-ion battery safety rules in 2007, according to an investigation by the Wall Street Journal.