What was found
(CAN) ON TAKEOFF ROLL, NR 2 ENGINE OIL FILTER BYPASS LIGHT CAME ON FOLLOWED BY OIL QUANTITY AND OIL PRESSURE LOSS. TAKEOFF REJECTED. POST-FLIGHT INSPECTION OF THE GEARBOX FOUND ONE OF THE FOUR HELICOILS THAT HOLD THE OIL FILTER COVER ON, TO HAVE PULLED OUT OF ITS HOUSING. THIS CAUSED THE OIL FILTER TO DROP DOWN IN ONE CORNER CAUSING LOSS OF OIL AND OIL PRESSURE. THE GEARBOX WAS REMOVED FOR REPAIR.