10:35am EE was jack legging to install pins and screen in the back of Upper Mahler Incline on LT3435 when the steel broke about 5in from the machine due to a flaw. The Leg fully extended. EE went over handrail at height of around 13ft 5in landing on EE's left side & hitting EE's head. Mine Rescue stabilized and transported from heading to surface on back board and cervical collar.