What was found
(CAN) THE AIRCRAFT WAS ON FINAL APPROACH. WHEN BRINGING THE GEAR DOWN, THE CREW RECEIVED A GEAR UNSAFE WARNING AND NOTICED THAT THE MAIN GEARS WERE NOT DOWN AND LOCKED. THEY THEN GOT AN L HYD PRESS LOW INDICATION. THE CREW INITIATED A `GO AROUND` AND ASKED THE TOWER TO LOOK AT THE MAIN GEAR. TOWER STATED THAT THEY LOOKED AROUND HALFWAY DOWN. THE CREW ENTERED A HOLDING PATTERN AND RAN THE APPROPRIATE CHECKLISTS WHICH INCLUDED TO BRING THE GEAR DOWN MANUALLY. THE GEAR INDICATED DOWN AND LOCKED. THE CHECKLIST ALSO SPECIFIED TO TURN OFF THE L HYDRAULIC PUMP AND SHUTOFF VALVE. THE LEFT HYDRAULIC QUANTITY INDICATION SHOWED 0%. QUITE OF BIT A FLUID WAS FOUND IN THE REAR BAY COMPARTMENT WHICH WAS REMOVED AND THEN THE AREA CLEANED WITH ALCOHOL. THE CREW ALSO MENTIONED THEY GOT A BRIEF PTU FAIL CAS INDICATION WHEN THE GEAR FAILED TO COME DOWN. MAINTENANCE CREW CONFIRMED THAT THE QUICK-DISCONNECT COUPLING FOR THE GROUND HYDRAULIC POWER CONNECTION FAILED. (TC# 20190627017)