What was found
WHILE TESTING SPOILERS, AILERONS AND FLAPS A LARGE HYDRAULIC LEAK WAS NOTICED FROM THE HORIZONTAL STAB COMPARTMENT. CONDITIONS IMMEDIATELY PRIOR TO SHUTDOWN OF HYDRAULIC. LT HYD PUMP OFF (QTY. 1.4), THEN RT HYD PUMP ON(QTY.0.70), BIG PUDDLE ON THE FLOOR, HORIZ STAB COMPARTMENT WET, NO MIST. PLU TEST HAS BEEN ACCOMPLISHED DURING PRE-DEACT PHASE OF CHECK, AND PASSED. REPLACED PTU.