As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
YYJ- LOST BOTH FLIGHT DIRECTORS ON APPROACH. PLACED ON MEL 34-60-1. CLEARED ON 9/12. FOUND CAPT'S TCS SWITCH STUCK IN ACTIVE POSITION. REPLACED TCS SWITCH ON CAPT'S CONTROL WHEEL. PERFORMED OPERATIONAL TEST OF FLIGHT DIRECTOR AND A/P IAW Q400 TC'S 6221101 & 6221102, ALL CHECKS GOOD. A/C AND PLACARD NOW READS CAT III. RETURNED TO SERVICE.