What was found
WHEN SELECTING GEAR DOWN, RECD HYD 3 LOW PRESS CAUTION MESSAGE. EXECUTED QRH PROCEDURE, HYD SYS SHOWED 0 PERCENT SYS QUANTITY, PERFORMED ALTERNATE GEAR EXTENSION, ON POST FLIGHT FOUND HYD FLUID ON UNDERSIDE OF FUSELAGE. UNABLE TO STOW ALTERNATE EXTENSION HANDLE. EMERGENCY DECLARED AS A PRECAUTION. R & R NR 3A HYD PUMP PRESSURE HOSE IAW AMM 29-12-03. LEAK AND OPS CHECKED GOOD. ACFT OK FOR SERVICE.