EE WAS USING SCOOP TO UNLOAD PALLET OF 6"" BLOCK FROM FLAT CAR, WHILE PULLING BLOCK INTO BUCKET, CHAIN GOT UNDER BUCKET. EE LOWERED BUCKET TO RELEASE CHAIN. WHILE BACKING UP, SCOOP FELL OFF OF CAR CAUSING EE TO BE BOUNCED AROUND IN DECK STRIKING HEAD AND RT SHOULD ON CANOPY.