What was found
DURING TAXI OUT RUDDER RATIO EICAS MSG & DISCREET LIGHT ILLUMINATED ON A/C RETURENED TO GATE (BTB) AND MTX GROUNDED A/C. T/S AS PER FIM 27-09 FT 814, PERFORMED BITE TEST TO LEFT AND RIGHT NO, NO FAULTS NOTED, NO FAULT FOUND, PRIOR TO BITE ACTION, PERFORMED OPERATIONAL RUDDER RATIO CHECK SYST CHECKED NORMAL LEFT AND RIGHT AMM 27-21-13. OPERATED SYST. WITH BOTH ENG. RUNNING NO FAULTS WERE DISPLAYED IN EICAS. IAW AMM 71-00-00. SYSTEM CHECKED OK AT THIS TIME. AC REMAIN ETOPS 180. AND RETURNED A/C TO SERVICE