As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
PHX - DURING TEST FLIGHT, LEFT PROPELLER RPM STARTED TO DROP OFF. RPM'S WENT FROM 1700 RPM TO 1200 RPM AND CONTINUED DOWN INTO FEATHER. THE CREW SHUT DOWN THE LEFT ENGINE AND LANDED WITHOUT FURTHER INCIDENT. MAINTENANCE REMOVED AND REPLACED THE PROPELLER AND THE POWER SECTION. TEAR DOWN INFORMATION WILL BE FORTHCOMING. (X)