What was found
YYZ - FLT 1611 - AFTER TAKEOFF YYZ, TRAILING EDGE FLAPS WOULD ONLY RETRACT TO 5 DEGREES. AIRCRAFT RETURNED TO YYZ AND LANDED WITHOUT INCIDENT. REPLACED FLAP CONTROL DATA UNIT. SYSTEM GROUND CHECKED, NORMAL OPERATION. FUNCTIONAL CHECK FLIGHT ACCOMPLISHED WITH NO DEFECTS NOTED. (X)