What was found
(CAN) PILOTS REPORTED THAT THE IB LEADING EDGE DEICE BOOT WAS NOT FUNCTIONING. THE DEICE SYSTEM WAS TESTED AND THE SNAG WAS CONFIRMED. WHEN THE LEADING EDGE WAS REMOVED TO CHECK THE BOOT SYSTEM EVIDENCE OF SEVERE ARCING WAS FOUND IN THE VICINITY OF THE START RELAYS. IT IS SUSPECTED THAT THE DEICE HOSE WAS ROUTED IMPROPERLY TO THE LEADING EDGE. OVER TIME THE HOSE CHAFED ON THE WIRING FROM THE RELAYS. MAINTENANCE REPLACED THE LEADING EDGE AS WELL AS ANY CONNECTORS THAT WERE DAMAGED. (TC NR 20070327001)