MECHANIC HAD TAKEN FLOOR BOARD OUT OF A DOZER. THE GREASER WAS CHECKING HYDRAULIC OIL. HE WENT THRU THE CAB TO GET TO THE HYDRAULIC TANK ON THE OTHER SIDE OF DOZER. IT WAS DARK AND HE DIDN'T H AVE HIS FLASH LIGHT. HE THEN STEPPED INTO THE CAB AND FELL THU THE OPENING IN FLOOR BOARD.