As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
CREW REPORTED THAT THE NR 2 ENGINE WAS SURGING 15 - 20 PERCENT TORQUE IN FLIGHT WITH THE PROPS AT 1050. DECLARED AN EMERGENCY AND RETURNED TO THE FIELD. MX TRACED THE ISSUE A THE PROP CONTROL UNIT. UPON REPLACEMENT OF THE PCU AN OPERATIONAL CHECK PRODUCED SATISFACTORY RESULTS.