As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
YYJ - ALL LANDING GEAR DOOR OPENED UNCOMMANDED, NOSE DOORS REMAINED OPEN, MAIN DOORS CLOSED. OCCURRED IN LEVEL FLIGHT AT 8000 MSL AT 238 KTS. RAN CHECK LIST AND GEAR EXTENDED WITH ALTERNATE METHOD WITH NO OTHER PROBLEMS. LANDING UNEVENTFUL. REMOVED AND REPLACED NLG DOOR CLOSE PROX SENSOR (S-19). LG OPS CHECKED GOOD IAW Q400 AMM 32-31-00-710-801. RETURNED TO SERVICE.