Cargolux flight CV6857, a Boeing 747-4R7F, was cleared for takeoff on runway 06 for a scheduled freight flight from Luxembourg Airport (ELLX) to Chicago O’Hare International Airport (KORD). Shortly after rotation, the Pilot Monitoring (PM) was not able to select gear-up and a ?GEAR TILT? EICAS message was triggered, followed by a ?GEAR DISAGREE? EICAS message. The aircraft proceeded to the DIK holding with the gear extended, where the crew performed the related non-normal checklists, decided to dump fuel and return to ELLX with the gear extended. In order to be cleared to dump fuel over land, the crew declared an emergency, and the aircraft was vectored to an area over Belgium for fuel dumping. At 16:51:30, after dumping approximately 40 tons of fuel at FL100, the aircraft was vectored back to ELLX for an ILS3 approach to RWY 06. At 16:59:04 the aircraft was cleared to land on RWY 06. When the aircraft touched down at 17:00:46, the wheel truck of the RH BLG with part of the inner cylinder attached separated from the aircraft. In this process, the separated gear assembly impacted the lower part of the aft fuselage multiple times and struck the righthand horizontal stabilizer. The crew was not aware of the RH BLG separation until they were informed by the tower that the aircraft had lost part of its landing gear on touchdown with four wheels attached. The crew then immobilized the aircraft on the runway. Airport surveillance video footage showed that after becoming airborne, the RH BLG wheel truck initially rotated to a normal pitch-up position before an over-extension of the strut could be observed. The over-extension was accompanied by a vapor release. During climb out, the RH BLG wheel truck could be observed in a pitch-down position. It was found that the upper bearing carrier had failed, with the bearing and piston ring retention lands sheared off.