What was found
(CAN) PRELIMINARY REPORT, SUSPECT THAT THE SHUTTLE VALVE THAT DIRECTS HYDRAULICS TO THE UP- OR DOWN-SIDE OF THE LANDING GEAR WAS STUCK OR BROKEN IN THE UP DIRECTION. WHEN THE L/G WAS SELECTED DOWN ON THE ARRIVAL, NOTHING HAPPENED EXCEPT THE L/G DOORS OPENED THE FIRST TIME, NOTHING AT ALL ON THE SECOND ATTEMPT. THE CREW WENT AROUND AND PUT THE L/G DOWN WITH EMERGENCY SYSTEM. IT WORKED AND THEY HAD THREE GREEN, BUT THE EMERGENCY GEAR EXTENSION LEVER DID NOT LOCK AS IT SHOULD, AND THE L/G RETRACTED ON ITS OWN SHORTLY THEREAFTER! THE EMERGENCY SYSTEM WAS RE-ACTIVATED, THE L/G WENT DOWN AS IT SHOULD AND THE LEVER WAS HELD IN THE DOWN POSITION. THREE GREEN, NORMAL LANDING, AND THE A/C TURNED ONTO A TAXIWAY AND W