Garfield the Cat hates Mondays, but Boeing (NYSE: BA) investors have to be starting to fear weekends.

Last Saturday, the company was hit with a bit of bad news when an inexperienced pilot crash landed one of its 777 airliners at San Francisco International Airport. This week, the weekend hadn't even fully begun when news emerged from London's Heathrow that another Boeing plane was on fire.

This time, it was an Ethiopian Airlines Boeing 787 Dreamliner at issue. According to press updates out of Heathrow, an Ethiopian Airlines787 was parked on a remote parking stand when a fire broke out aboard the plane. No passengers were on board at the time. Regardless, Heathrow says it followed standard procedure by deploying fire crews to the plane, and temporarily suspending arrivals and departures at the airport.

At last report, Heathrow was once again "fully operational," barring a few "flight delays and cancellations."

As for the Ethiopian Dreamliner, the cause of the on-board fire has not yet been identified, and experts are cautioning against jumping to conclusions that the plane's burning-battery issues, of several months ago, have resurfaced. Former U.S. National Transportation Safety Board Chairman Mark Rosenker said that since the scorched portion of the plane's exterior is near the rear galley, it could have started from as simple a cause as a coffee pot left on too long.

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