As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
IAD/LGA - FLT 6500 - DURING CRUISE AT 0645 HOURS ON 4-9-98, AIRCRAFT MADE AN UNSCHEUDLED LANDING AT IAD DUE TO LT FHSI SCREEN WENT BLANK. AIRCRAFT RETURNED TO GATE WITH NO FURTHER PROBLEMS. MAINTENANCE INSPECTED AND REMOVED AND REPLACED EHSI SCREEN, OPS CHECK OK. AIRCRAFT WAS RELEASED AND APPROVED FOR RETURN TO SERVICE. (X)