The agency announced Sunday it would soon issue a directive, while United said it would ground its fleet of 777s with the engine in question pending the FAA directive.

"We have been working on this nonstop since Saturday afternoon and I am confident that we will get it right," Dickson said. "We want to understand what happened and then take the necessary steps to prevent a similar occurrence in the future."

(This story fixes headline from 77 to 777))

(Reporting by David Shepardson, Editing by Franklin Paul)