What was found
AFTER DEPARTURE, FLAPS WERE SELECTED UP AND FAILED TO RETRACT FULLY. INDICATOR SHOWED APPROX 8* OF FLAPS. FLAP DEPLOYMENT WAS VERIFIED VISUALLY BY FO. NO ASSEMETRY WAS NOTED. RETURNED FOR LANDING. FLAPS DEPLOYED NORMALLY. LANDING UNEVENTFUL. PERFORMED NUMEROUS OPERATIONAL TESTS OF WING FLAPS IAW JIC 27-51-00, OPT 10000. OPS CHECKED SATISFACTORY. MAINTENANCE PERFORMED AN OPERATIONAL TESTS OF WING FLAPS IAW JIC 27-51-00 OPT 10000, TO INCLUDE A GVI OF THE AIRCRAFT TO LOOK FOR TRIPPED CIRCUIT BREAKERS, OBVIOUS DAMAGE, HYDRAULIC LEAKS AND CORRECT HYDRAULIC SERVICE LEVEL. ALL CHECKS SATISFACTORY. COULD NOT DUPLICATE ISSUE. AIRCRAFT RETURNED TO SERVICE.