As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
AFTER TAKEOFF WHILE CLIMBING THROUGH ROUGHLY 6000 FEET THE TORQUE AND ITT BEGAN TO SLOWLY FALL. AFTER PILOT NOTICED THE DECREASE HE REQUESTED TO GO BACK TOWARD THE AIRPORT AND BEGAN TO TROUBLE SHOOT. HE INCREASED AND DECREASED THE POWER LEVERS AND NOTICED VERY LITTLE CHANGE. THE TORQUE KEP SLOWLY DECREASING. HE CYCLED THROUGH INVERTERS TO ENSURE IT WASN'T A GAUGE. AT THAT TIME HE REQUESTED A CLEARANCE BACK TO THE AIRPORT AT WHICH TIME HE EXECUTED A VISUAL APPROACH TO RUNWAY 28R.