A Delta Airlines Boeing 747-400 performing flight from Tokyo Narita to Detroit with 310 passengers and 17 crew was over the Pacific Ocean when the crew reported problems with the #1 engine (PW4056, outboard left hand) and decided to return to Tokyo Narita, where the aircraft landed back about 7 hours after departure.
A passenger reported about 3.5 hours into the flight there was noise and vibrations. Soon after the aircraft descended to FL280 and turned around.
The captain announced that one of the engines had ceased operation, Tokyo Narita was still the closest airport and they would return to Narita.
The passengers were put into hotels and rebooked onto flight DL-9876 the following day, however, that flight was cancelled. A number of passengers have been rebooked onto DL-276 of Jun 8th.
Japan’s Ministry of Transport reported the aircraft declared emergency due to engine trouble.