THE MECHANIC HELPER HAD TO CLIMB ONTO THE 2500 HITACHI SHOVEL TO REPAIR AND FUEL THE SHOVEL. THE BOARDING LADDER COULD NOT BE USED BECAUSE THE CRAWLER TRACK WAS IN THE WAY. HE USED A STEPLADDE R TO GAIN ACCESS TO THE SHOVEL. AS HE STEPPED OFF THE LADDER AND ONTO THE WALKWAY HIS HEEL CAUGHT A FIRE EXTINGUISHER AS HE FELL FORWARD. HIS ANKLE BROKE BEFORE HE REGAINED BALANCE.