The Boeing 787, flying from the Washington, D.C., area to Munich, had to make a hasty return to the airport "to address a mechanical issue," United said.

On July 25, United Airlines Flight 108 made an emergency return to its departure site, Washington Dulles International Airport, after experiencing a suspected engine failure.

A United Airlines pilot declared mayday late last month, suspecting possible engine failure after takeoff from Dulles International Airport near Washington, D.C. “Engine failure, left engine, United 108 declaring an emergency.