What was found
L HYD QTY ZERO IN FLIGHT. HAD A SLOW LEAK AT CRUISE THAT TOOK ABOUT 50 MINUTES TO REACH ZERO. SUBSEQUENTLY WE GOT L HYD SYS PRESS. COMPLIED WITH QRH AND SHUT DOWN LH SYSTEM. FOUND VERTICLE STAB HYD MANIFOLD TO BE LEAKING FROM UNION ITEM 45 IN A/C IPC 27-21-56- 01. REMOVED AND REPLACED PACKING PART NUMBER NAS1612-8A PER 20-10-19 AND 20-11-00- 2. SERVICED LEFT HYD SYSTEM PER 12-12-01. LEAK CHECKED NO LEAKS NOTED. QTY STAYED THE SAME THROUGHOUT PRESSURIZATION AND CYCLED FLIGHT CONTROLS NO HYD QTY LOST.