What was found
SHORTLEY AFTER T/O NR 2 HYD ISOLATION VALVE . NR 2ENG HYD PUMP, SPLROUTBD, ROLL SPLR OUTBD HYD, NR 2 RUDDER HYD. ALL 3 GEAR DOOR AMBER AND ALL 3 RED LT NOSE RIGHT ILLUMINATED. GEAR HANDLE AMBER LIGHT. PTU FAIL ON PTU SWITCH. HYD PRESSURE NR 2 SYS AT 0 PSI. 10 MINS INTO FLT, NR 2 SYSTEM PRESS RETURNED TO NORMAL. ALL SYSTEM CAUTION LIGHTS WENT DARK. PTU FAIL LIGHT REMAINED ILLUMATED.LANDING GEAR RETRACTED. RETURNED TO THE FIELD. LANDING UNEVENTFUL. REMOVED FROM SERVICE. FOUND A LARGE AMOUNT OF AIR IN NR 2 HYD SYS. REMOVED AIR FROM SYS. WORK ACCOMPISHED ON WORK ORDER 327296.