As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
AC HAD SOME SUDDEN YAWING WHEN PASSING THROUGH A SPECIFIC COLLECTIVE POWER SETTING THAT WAS REPEATABLE AND INDICATED A SUDDEN CHANGE OF ENGINE TORQUE SUCH AS ONE MAY EXPERIENCE WITH COMPRESSOR STALLS. NO FAULT CODES WERE GENERATED AD THE ENGINE HAD NO OBSERVABLE DEFECT WHEN EXAMINED. APPARENT THAT A DEAD SPOT HAD DEVELOPED IN THE POTENTIOMETER SIGNAL CONTROLLING ENGINE ANTICIPATION. NEW POTENTIOMETER WAS INSTALLED WITH NO FURTHER DEFECT. (K)