As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
CLE/IAD - FLT 6491 - DURING TAXI AT 1825 HOURS ON 5-27-97, AIRCRAFT RETURNED TO GATE WITH NO FURTHER PROBLEMS DUE TO LT RPM INDICATION INOPERABLE. MAINTENANCE INSPECTED AND REMOVED AND REPLACED TACH GENERATOR, OPS CHECK OK. AIRCRAFT WAS RELEASED AND RETURNED TO SERVICE. (X)