What was found
FLT 6339 - IAD-EWR - DURING TAXI-OUT, EXPERIENCED A RIGHT ADI INDICATOR SHOWING 9 DEGREES PITCH UP. AIRCRAFT RETURNED TO THE GATE WHERE THE MAINTENANCE TECHNICIANS TROUBLESHOT THE DISCREPANCY AND FOUND THAT THE RIGHT ADI INDICATOR HAD FAILED. MAINTENANCE REPLACED THE RIGHT ADI INDICATOR IAW WITH ALL MAINTENANCE PROCEDURES. AIRCRAFT WAS THEN RELEASED AND APPROVED FOR RETURN TO SERVICE. (M)