What was found
ON APP FLAP EXT 2 TO 5 AMBER L/E FLAP LIGHT REMAINED ILLUM. POSITION TEST SHOWED NO LIGHT FOR LEFT NR 4 SLAT RETRACTED. PERFORMED APP PER POM. C/W PROCS FOR LANDING. TAXIING AFTER LAND UPON FLAP RETRACTION, LOST A HYD SYS FLUID. PERFORMED PROCS AS PER POM. STOPPED A/C AND TOWED IN. REPLACED LT WING NR 4 SLAT ACT PER MM, LEAK CHECK OK. HYD SERVICED, LIGHTS AND OPN CKS NORMAL. SECURED ACCESS PANELS RII C/W PER CVG QA.