What was found
ON DEPARTURE, FLAPS STUCK AT 15 DEGREES, PERFORMED E&A CHECKLIST. CAUTION LIGHT EXTINGUISHED BUT REAPPEARED AFTER TRYING TO SELECT FLAPS UP. FLAPS REMAINED AT 15. RETURNED TO FIELD. LANDING UNEVENTFUL. PERFORMED OPS TEST OF WING FLAPS IAW AMM 27-50-00-710-801. OPS TEST PASSED, NO FAULTS NOTED. R & R FLAP CONTROL UNIT AS PROCAUTIONARY MEASURE IAW AMM 27-51-01-000-801 AND 27-51-01-400-801. FUNCTIONAL TEST PASSED, NO FAULTS NOTED. PERFORMED FREEDOM OF MOVEMENT CHECK ON FLIGHT CONTROLS. CHECK GOOD. CAUTION LIGHT DID NOT ILLUMINATE. RETURNED TO SERVICE.