What was found
AT 5,000 FLT ON DEPT, SYS-A HYD LOW PRESS LIGHT ILLUM WITH FWD PANEL SYS A-LIGHT. SYS-A HYD QTY AND PRESS INDICATES ZERO. EMERGENCY CHECK LIST COMPLETED AND FUEL DUMPED, RETURNED TO DFW. FOUND NR 4 SLAT ACT RUPTURED. REPLACED ACT AND SERVICED HYD TO FULL. NR 4 SLAT ACT LEAKS AND OPN CKS GOOD. NO OTHER LEAKS DETECTED.