As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
IAD/BDL - FLT 6521 - DURING CRUISE AT 1635 HOURS ON 3-38-29, AIRCRAFT MADE AN UNSCHEDULED LANDING DUE TO LT ENGINE RPM HAS TO BE PULLED BACK ALMOST TO THE TAXI RANGE TO GET 97 PERCENT. AIRCRAFT LANDED AT IAD AND RETURNED TO GATE WITH NO FURTHER PROBLEMS. MAINTENANCE INSPECTED AND REMOVED AND REPLACED LT PROP GOVERNOR, OPS CHECK OK. AIRCRAFT WAS RELEASED AND RETURNED TO SERVICE. (X)