As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
IAD/PHL - FLT 6237 - DURING CRUISE AT 1314 HOURS ON 6-28-98, AIRCRAFT MADE AN UNSCHEUDLED LANDING AT IAD DUE TO INVERTER FAIL WARNING LIGHT IN-FLIGHT. AIRCRAFT RETURNED TO GATE WITH NO FURTHER PROBLEMS. MAINTENANCE INSPECTED AND REMOVED AND REPLACED INVERTER. OPS CHECK OK. AIRCRAFT WAS RELEASED AND RETURNED TO SERVICE. (X)