A few days ago, Lufthansa updated their timetable to reflect a switch in aircraft that will be used between Frankfurt and Detroit.
Beginning July 2, Lufthansa will begin flying the 747-400 on their daily flight to the Motor City, replacing the A340-300 that has been on the route until now. This will be the case at least for the Summer timetable which expires on September 29. LH will most likely downgage the route to a smaller aircraft for Winter 2017/18, but at least for the Summer and early Fall, passengers can enjoy the Queen of the Skies from DTW.
This covers flight LH442 that departs FRA at 10:00a and arrives in Detroit at 12:40p, and LH443 that departs Detroit at 3:50p, arriving in Frankfurt at 5:40a the following morning.