What was found
HYD LOW ANNUNCIATOR ILLUMINATED 1 HOUR AFTER TAKEOFF AT FL 390. HYD VOLUME INDICATED =160 CU IN VOLUME CONTINUED TO DECREASE TO 100 CU IN AND HYD PRESS LOW ANNUNCIATORS ILLUMINATED. LANDING GEAR WOULD NOT EXTEND AND HAD TO BE BLOWN DOWN VIA EMERG EXTENSION CHECKLIST. INSPECTION AFTER LANDING REVEALED HYD FLUID OVER THE AFT END OF AIRCRAFT, INCLUDING THE BAGGAGE COMPARTMENT AND HELL HOLE. FOUND LT ENG HYD. PUMP LEAKING. REMOVED AND REPLACED HYD. PUMP. PERFORMED ENG. RUN. OPS/LEAK CHECK GOOD IAW CE 650 MM CHAP. 29-10-04.