As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
AIRCRAFT WAS GROUNDED: AFTER TAKE OFF LEADING EDGE FLAP TRANSIT ILLUMINATED AT 400 FEET. LEFT OUTBOARD LEADING EDGE DEVICE INDICATED AMBER. EMERGENCY DECLARED, RETURNED TO YYC LANDING SAFELY. REPLACED #1 LEADING EDGE SLAT PROXIMITY SENSOR PER AMM TASK 27-88-11-400-801. ACCOMPLISHED SATISFACTORY LEADING EDGE FLAP AND SLAT PROXIMITY SENSOR TEST PER AMM 27-88-11-700-80.