The FAA is undertaking a comprehensive review of the critical systems of Boeing's 787s after a fire and a fuel leak earlier this week, but officials say they are confident about the safety of the jet.

  The review will include the design, manufacture and assembly of  its systems, the FAA said.

U.S. Transportation Secretary Ray LaHood said at a news conference Friday said he was concerned about recent events regarding the 787, but pointed out that the FAA logged 200,000 hours on the jet's certification to ensure it met the required level of safety.

“We are confident about the safety of this aircraft, but we are concerned about these incidents,” said FAA Administrator Michael Huerta.

Boeing Commercial Airplanes President and CEO Ray Conner said the 787 had “the most robust and rigorous certification process in the history of aviation."

 The 787 relies more than any other modern airliner on electrical signals to help power nearly everything the plane does. It's also the first Boeing plane to use rechargeable lithium ion batteries, which charge faster and can be molded to space-saving shapes compared to other airplane batteries. The plane is made with lightweight composite materials instead of aluminum.

The investigation will focus on the electrical systems.

A fire ignited Monday in the battery pack of an auxiliary power unit of a Japan Airlines 787 empty of passengers as the plane sat on the tarmac at Boston's Logan International Airport. It took firefighters 40 minutes to put out the blaze. Also this week, a fuel leak delayed a flight from Boston to Tokyo of another Japan Airlines 787.

   On Friday, Japan's All Nippon Airways reported two new cases of problems with the aircraft. ANA spokeswoman Ayumi Kunimatsu said a very small amount of oil was discovered leaking from the left engine of a 787 flight from southern Japan's Miyazaki airport to Tokyo.

   The jet returned to Miyazaki, but after checks found no safety risk it flew to Tokyo. ANA said on another flight, to Matsuyama on the island of Shikoku, glass in a cockpit window cracked and the aircraft was grounded for repairs.    

"Every new commercial airplane has issues as it enters service,” Conner said.

Aviation analyst Scott Hamilton cautioned not to read too much into the investigation.

"The systems are bleeding-edge technology, just all kinds of new stuff, so you've got to expect that a new airplane with all this new technology is going to have some teething issues, and any new airplane with a series of incidents, is going to get the headlines," said Hamilton.

While transportation officials said such a review was unprecedented, Hamilton said it was.

The FAA  gave no indication that the agency intends to limit or prohibit the 787 from flying during the review.

The Dreamliner is currently being used in more than 150 flights a day.