As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
DURING TAKEOFF FLOW POWER SET AT 100 PERCENT TORQUE AUTOCOARSEN SWITCHED FROM HI TO LOW AND REMAINED IN LOW. AIR RETURN TO DTW. MAINTENANCE REPLACED LT & RT ENGINE AUTOCOARSEN P3 SWITCHES PN 1103P0620 IAW AMM GROUND. RAN AC FOR SEVERAL MINUTES NO DISCREPANCIES NOTED . OPS CHECK GOOD.