What was found
FLAP ASYMMETRY LIGHT ILLUMINATED DURING RETRACTION AFTER TAKEOFF. FLAP MOVEMENT STOPPED AT EIGHT DEGREES. ACCOMPLISHED ABNORMAL CHECKLIST AND RETURNED TO LAND. FOUND ASYMMETRY RETURN SPRING NOT FULLY RETURNING. CLEANED AND LUBRICATED LEFT FLAP ASYMMETRY SPRING. FLAPS OPS CHECKED NUMEROUS TIMES. OPS CHECKED GOOD IAW YS-11 M.M. 27-55-0. ALSO, REPLACED THE LEFT FLAP ASYMMETRY SWITCH DRUM AT ILN, AFTER NEXT FLIGHT, IAW YS-11 MM CHAPTER 27. OPS CHECKED GOOD.