This was the aircraft’s first flight after maintenance, during which the Landing Gear Control Module (LGCM) was replaced. After retracting the landing gear following takeoff from Heathrow, the crew were unable to move the landing gear lever from the ‘UP’ to the ‘OFF’ position, as it had become jammed in the ‘UP’ detent. The crew elected to return to Heathrow and, in accordance with 747 Flight Crew Operations Manual Non-Normal Checklist procedures, the landing gear was lowered using the alternate extension system. The aircraft landed safely, with only the nose and body landing gear deployed.
The landing gear lever jam was attributed to a maintenance error which had resulted in incorrect rigging of the landing gear lever system during the LGCM replacement, due to the omission to insert a rig pin in the selector valve quadrant. The operator has taken safety actions intended to prevent a recurrence.