What was found
MLG WOULD NOT EXTEND. WHEN MAIN GEAR HANDLE PLACED IN DOWN POSITION, 3 AMBER CASS MESSAGES ILLUMUNATED. (1) LOW HYD QUANTITY. (2) MAIN LND GEAR NOT DOWN. (3) NOSE LND GEAR NOT DOWN. (NO GEAR MOVEMENT AT ALL). LOWERED MAIN GEAR USING, "LANDING GEAR FAILURE TO EXTEND" CHECK LIST. HYD QUANTITY ON HYD PAGE RETURNED TO NORMAL (FULL) AFTER GEAR BLOWDOWN. NORMAL OPS AFTER ALT GEAR EXTENTION. FUNCTION TEST CARRIED OUT, DEFECT CONFIRMED. LANDING GEAR CONTROL CB POPS WHEN GEAR HANDLE SELECTED DOWN. LANDING GEAR SELECTOR DUMP VALVE REPLACED.