By Simon Hradecky, created Wednesday, Jan 20th 2021 22:45Z, last updated Wednesday, Jan 20th 2021 22:45Z

An ANA All Nippon Airways Boeing 777-300, registration JA787A performing flight NH-8549 from Chicago O'Hare,IL (USA) to Tokyo Narita (Japan), was climbing out of Chicago's runway 28R cleared to climb to 15,000 feet when the crew stopped the climb at 12000 feet due to problems with the left hand engine (GE90) and requested and was cleared to enter a hold. After about 20 minutes in the hold at 6000 feet the crew advised they had now been able to stabilize the engine parameters and were ready to dump fuel. The aircraft was being vectored over Lake Michigan while dumping fuel, the left hand engine is kept at idle power. While holding over Lake Michigan the crew reported they had left engine high N1 vibrations. The aircraft landed safely on runway 22L about 95 minutes after departure.

https://flightaware.com/live/flight/ANA8549/history/20210120/2145Z/KORD/RJAA