As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
DURING DESCENT TO DROP OFF PASSENGERS AND CARGO, THE NR 2 ENGINE PTT BEGAN TO RISE TO 905C AND THE N1 WAS AT 102% FOR AT LEAST 15 SECONDS. ACFT RETURNED TO BASE. NO DUPLICATION OF INCIDENT COULD BE MADE ON THE GROUND. ENGINE AND FCU WILL BE REPLACED.