As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
FLT 6516 - IAD-LGA - DURING TAXI, EXPERIENCED A DISCREPANCY WITH THE CAPTAINS EHSI SCREEN GOING BLANK. AIRCRAFT RETURNED TO THE GATE, WHERE MAINTENANCE CONTROL AND MAINTENANCE WAS NOTIFIED. MAINTENANCE REMOVED AND REPLACED THE EHSI INDICATOR IAW MAINTENANCE PROCEDURES. ALL CHECKS WERE ACCOMPLISHED AS OUTLINED IN THE MM. AIRCRAFT WAS THEN RELEASED FOR SERVICE. (M)