As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
AFTER NORMAL TAXI OUT TO THE RUNWAY END, THE NR 1 ENGINE PROPELLER WENT INTO FEATHER UNCOMMANDED TO 200 RPM. TAXI BACK TO THE GATE. AFTER 5 MINUTES TAXI BACK TO THE GATE, THE ENGINE CAME OUT OF FEATHER ON ITS OWN. REPLACED THE NR 1 PEC, CHANNEL "A" HARNESS ASSY, NR 1 PCU. OPS CHECKS GOOD. PROPELLER FEATHERED AND UNFEATHERED AS COMMANDED.