EE WAS DRAGGING ROCKDUST HOSE WALKING BACKWARDS ON TOP OF AN OVERCAST HIS LEFT LEG FELL THRU THE OVERCAST TIN AND HIS RIGHT KNEE STRUCK MATERIAL LAYING ON TOP OF THE OVERCAST. CAUSE OF INJURY WAS DETERIRATED TINS. COMPLIANCE WITH RULES/REGS WAS NOT A FACTOR, PROTECTIVE EQUIP NOT A FACTOR, MINER KNOWLEDGE A FACTOR, MINING/EQUP/SYSTEMS COULD BE A FACTOR.