As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
(CAN) NLG FAILED TO EXTEND DURING APPROACH. AT LAST, THE CREW RELEASED THE NLG WITH MANUAL RELEASE HANDLE. THE ROOT CAUSE OF THE INCIDENT WAS NLG DOORS CAN`T BE OPENED. AFTER THE MAINTENANCE REPLACED THE DOOR SELECTOR VALVE, THE NLG DOORS CAN BE OPERATED NORMALLY AND THE FUNCTIONAL TEST OF LANDING GEAR EXTENSION, RETRACTION WAS OK.