What was found
(CAN) THE PILOT MADE TWO ATTEMPTS TO START THE AIRCRAFT. THE ENGINE FAILED TO START AND THE PILOT NOTED THAT THE IGNITION LIGHT ON THE CAWS PANEL HAD NOT ILLUMINATED DURING EITHER ATTEMPT. THE CAWS PANEL LIGHTS WERE TESTED AND FOUND SERVICEABLE. AFTER APPROX. 5 MINUTES A THIRD STARTING SEQUENCE WAS INITIATED AND SUCCESSFUL. THE AIRCRAFT RETURNED TO BASE WITHOUT FURTHER INCIDENT. MAINTENANCE CARRIED STARTED THE AIRCRAFT WITH NO INDICATION OF ANY DEFECT. THE AIRCRAFT WAS SHUT DOWN, AND FURTHER INVESTIGATION REVEALED THAT THE IGNITION EXCITER BOX WAS NOT FIRING IAW THE ENGINE MFG REQUIREMENTS. A REPLACEMENT UNIT WAS INSTALLED, AND TESTED SERVICEABLE.