EE WAS PERFORMING FUELING AND SERVICING WORK ON A D11R DOZER. WHILE DISMOUNTING THE DOZER, HIS FOOT SLIPPED OFF THE MAIN DOZER SUPPORT ARM STEP, AND HE FELL STRIKING HIS CHIN ON THE UPPER SURF ACE OF THE DOZER TILT CYLINDER. THERE WERE NO SLIPPERY SURFACES ON THE DOZER, HOWEVER THE WORKER DID HAVE AN ACCUMULATION OF OIL AND GREASE ON H IS SHOES.