What was found
AFTER T/O, DURING FLAP RETRACTION FROM 2 DEG TO UP, AMBER LEADING FLAPS LIGHT REMAINED ON, NR 3 SLAT AMBER LIGHT IND INTERMEDIATE POS, A-SYS HYD QTY OBSERVED AT ZERO. RED TAB CKLT ACCOMPLISHED. SAFETY WIRE BROKEN ON A FLUID S/O VALVES AND GPWS FLAP. UNEVENTFUL LANDING AT STL, GEAR PINNED AND TOWED TO PARKING. SAFETY WIRE BROKEN ON ALT FLAP SW. ZERO QTY AND PRESS. *S/D* REMOVED AND REPLACED NR 1 AND 2 'A' SYS HYD PUMP, REMOVED AND REPLACED NR 1 AND 2 HYD PUMP CASE DRAIN FILTERS, REMOVED AND REPLACED NR 3 L/E SLAT ACT, REMOVED AND REPLACED 'A' HYD RETURN FILTER ASSY. OPS AND FUNCTIONAL CHECKS NORMAL, REMOVED GEAR PINS.