Scrutiny of 787 fire ramps up; Boeing shares fall

Last month, a United Airlines 787 flying from Houston to Newark, N.J., diverted to New Orleans because of an electrical problem with a power distribution panel. Last week, United said it would delay the start of 787 flights from Houston to Lagos, Nigeria because it wanted to "improve the reliability of the aircraft."

In November 2010, a test flight had to make an emergency landing after an in-flight electrical fire. The fire delayed flight tests for several weeks while Boeing investigated.

Boeing said the fire on Monday appears to be unrelated to previous electrical problems on the 787.

"Nothing that we've seen in this case indicates a relationship to any previous 787 power system events," Boeing said in a prepared statement. Those earlier problems involved power panels elsewhere in a rear bay for electrical equipment. Boeing also said it "would be premature to discuss additional details at this stage" of the investigation.

Boeing said it has shared information about the prior events with the NTSB.

Shares of Chicago-based Boeing have fallen 4.6 percent since the fire was reported, wiping out almost $2.7 billion of the company's value. On Tuesday they fell $2, or 2.6 percent, to close at $74.13.

Investors may have been unnerved by the fire after it appeared that the mechanical and manufacturing kinks with the 787 had been worked out.

They may have also reacted to another 787 issue on Tuesday. A different Japan Airlines 787 at Logan had to be towed back to the gate after spilling 40 gallons of jet fuel. The flight was re-scheduled for later in the day.