As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
UPON APPROACH INTO DEN FROM DRO, CREW PUT GEAR HANDLE DOWN BUT GEAR DOORS & GEAR DID NOT COME DOWN. CREW TRIED TO CYCLE BUT GEAR AGAIN FAILED TO COME DOWN. CREW ABORTED LANDING TO TROUBLESHOOT. AFTER CONSULTING WITH MAINTENANCE CREW DID ALTERNATE GEAR EXTENSION AND GEAR CAME DOWN. AS A PRECAUTION CREW DECLARED AN EMERGENCY AND LANDED WITHOUT INCIDENT. AFTER LEAVING THE HIGH SPEED RUNWAY THE AIRCRAFT WAS STOPPED AND TOWED TO THE GATE. MAINTENANCE REMOVED AND REPLACED LANDING GEAR SELECTOR VALVE PER BOMBA AMM AND OPS CHECKED GOOD.