What was found
AMA TO IAH - ON DOWNWIND FOR LANDING IN IAH, THE AIRCRAFT WAS SLOWED TO 180 KNOTS AND 8 DEGREES OF FLAPS WERE ADDED. WHEN THE AIRCRAFT TURNED ONTO THE BASE LEG, THE FLAP LEVER WAS SET TO 20 DEGREES AND A FLAP FAIL MESSAGE APPEARED ON EICAS. THE QRH WAS FOLLOWED AND THE AIRCRAFT LANDED WITHOUT INCIDENT. THE AIRCRAFT WAS TAXIED TO THE GATE AND TURNED OVER TO MAINTENANCE. MAINTENANCE CHECKED THE FLAP ELECTRONIC CONTROL UNIT FOR FAULT CODES AND FOUND CODES POINTING TO THE FLAP POWER DRIVE UNIT. THE PDU WAS FOUND TO BE BINDING INTERNALLY AND WAS REPLACED. THE FLAPS WERE THEN RIGGED AND THE FLAP SYSTEM OPS CHECKED GOOD.