What was found
PASSING THRU FL 200 BLUE ADVISORY FLAP LOW SPEED MSG ON EICAS. WHEN MAKING FINAL APPROACH & SELECTING FLAPS 9 STILL HAD FLAPS 0 INDICATING ON EICAS. RMU SHOWED FLAPS 9 & IT COULD BE FELT IN A/C CONTROLS. FLAPS WERE EXTENDED TO 22 WITH A VISUAL INSPECTION THAT THEY WERE IN CORRECT POSITION, NO FLAP FAIL MESSAGE PRESENTED. FOUND CHANNEL NR 1 INOPERATIVE. REPLACED THE FLAP POWER DRIVE UNIT IAW AMM 27-53-04.ACCOMPLISHED FLAP ZERO DEGREE RIGGING IAW AMM 27-53-04. FLAP SYSTEM OPS CHECKED GOOD.