As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
UNCOMMANDED AUTOFEATHER WHILE ON APPROACH AT APPROX. FL40, THE CREW NOTED A MOMENTARY DROP IN POWER TURBINE SPEED AND TORQUE. THE ENGINE POWER RECOVERED TO NORMAL SETTINGS 12 SECONDS LATER WITH NO PILOT INPUT. AN UNEVENTFUL LANDING FOLLOWED. MULTIPLE FAULTS WERE RECORDED ON THE ENGINE ELECTRONIC CONTROL, TROUBLESHOOTING IS ON-GOING.