(NECN: Alysha Palumbo, Boston) - It's the second day in a row that a Japan Airlines Dreamliner flight #7 bound for Tokyo had issues before takeoff at Logan Airport in Boston.
Monday it was a fire in the auxillary power unit battery which is under investigation by the NTSB.
Tuesday it was a fuel spill.
Massport Aviation Director Edward Freni said, "The aircraft was stopped and some fuel vented out of the left side of the aircraft, the left fuel tank, about 40 gallons of fuel spilled on the surface, none of that fuel went into the ocean, we contained it right away, it was reported first by a pilot in the aircraft behind the JAL flight."
Freni says the 787 was towed back to the gate, and passengers deplaned while mechanics examined the plane.
The exact cause of the fuel spill is unknown, but the plane was eventually cleared for flight.
Freni said, "There are a couple of reasons that it could happen, it could be a fuel transfer from one tank to another, that could be one reason, or an overfueling process, we don't know, but the mechanics like I said have gone on the aircraft and determined there's no mechanical issues with that airplane."
"As the fuel warms up, as it comes out of the ground and it's a slightly warmer day, that fuel expands and it's designed to be vented overboard," said MIT Aeronautics Professor John Hansman.
Hansman says these are two unrelated incidents and he doesn't see Boeing grounding the fleet because of them.
Hansman said, "I think in the bottom line the airplane is a very solid airplane, these are teething problems, it's a new airplane, fairly advanced airplane, and I expect that they'll be worked out very quickly."