What was found
WHEN RETRACTING FLAPS, TE DISAGREE MSG APPEARED WHEN FLAP HANDLE WAS MOVED FROM 5 DEG TO 1 DEG. RETURNED TO JFK. *S/D* A FAULTY TRAILING EDGE FLAP POWER DRIVE UNIT BYPASS VALVE PREVENTED AFT FLAPS FROM RETRACTING TO THE COMMANDED POSITION. THE FLAP/SLAT ELECTRONICS UNIT SENSED THE DISAGREEMENT BETWEEN THE FLAP LEVER POSITION AND FLAP POSITION AND DROVE THE 'T/E FLAP DISAGREE' CAUTION ALERT MSG TO APPEAR ON EICAS AND THE 'TRAILING EDGE' AMBER LIGHT TO ILLUMINATE. THE BYPASS VALVE ON THE T/E FLAP PDU CONTROL VALVE WAS REPLACED AND TESTED AND THE FLAP/SLAT SYSTEM OPS CHECKED AND VERIFIED NORMAL PER MM.