As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
CREW RETURNED TO MSP DUE TO A PROPELLER RPM CONTROL/INDICATION FAULT. RPM PROP RPM WENT TO ZERO INFLIGHT. REMOVED AND REPLACED PROP RPM SENSOR AS REQUIRED PN 4088T42P01. REMOVED AND REPLACED PROP GAUGE AS REQ SN OFF 9710657 ON 324. OPS CHECKS GOOD.