A United flight made an emergency landing in Honolulu on Tuesday after a piece of the cover came off the right engine on a flight from San Francisco, United spokesman Charles Hobart said.
"Scariest flight of my life," passenger Maria Falaschi- tweeted.
Another passenger, Erik Haddad, recorded video of the engine as the plane flew over the Pacific.
"That looks bad, plane and simple," he wrote on Twitter describing the sight of pieces of metal missing from the front of the engine cowling.
Passenger Jeff Carter posted a video showing the shaking in the cabin as the plane descended to land.
He heard a "big metallic bang," he said, and then the plane began to shake.
Hobart said the pilots safely landed the aircraft at Daniel K. Inouye International Airport, taxied to the gate, and the passengers got off the plane as they normally would.
The Boeing 777 has two engines.