As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
PILOTS REPORTED THAT THE RT ENGINE NR 2 PROPELLER VIOLENTLY CYCLES IN AND OUT OF FEATHER. PROPS WERE FULL FWD, IDLE SLOWLY INCREASING, CAUSED YAWING AT 1500 FT ON APPROACH. MX CLEANED POWER LEVER AUTOFEATHER MICROSWITCHES AND PERFORMED OPSL CHECK OF AUTOFEATHER SYSTEM IAW MM 61-21-00. ALL CHECKS WERE GOOD.