As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
FLT 6420 - IAD-BUF - DURING CLIMB, THE FLIGHT EXPERIENCED A FLICKERING OF THE CAPTAINS VSI THEN GOING BLANK. AIRCRAFT RETURNED TO IAD WHERE MAINTENANCE TROUBLESHOT AND REMOVED AND REPLACED THE RT TCAS VSI INDICATOR. ALL CHECKS WERE ACCOMPLISHED AND THE AIRCRAFT WAS RELEASED FOR SERVICE. (M)