As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
DURING FLIGHT 3319, RT PROP INDICATES 1240. RIGHT ENGINE PROP RPM 1240 W/ CONDITIONER LEVER MAX RIGHT AFTER +10. APPROX 10 MINUTES LATER DROPPED BELOW 1180. QRH ENGINE SHUTDOWN BELOW 1200 RPM ACCOMMPLISHED. T/M LOCKOUT DID NOT CHANGE. AIR RETURN TO DTW. MAINTENANCE REMOVED AND REPLACED RT PROP OVERSPEED GOVERNOR, P/N ON/OFF 8210-163, S/N ON 2162706 IAW SAAB MM CH 61 AND 72. PERFORMED ALL OPS CHECK GOOD AT THIS TIME.