As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
RETURN TO BLOCKS. FLT NR 8797, ON TAXI TO RUNWAY PILOT NOTICED THAT THE PROP RPM GAUGE WAS STUCK AT 200 RPM. THE PAR (POWER ANALIZER AND RECORDER) UNIT SHOWS PROP RPM NORMAL. AC WAS TAXIED BACK TO RAMP FOR MAINTENANCE. MAINTENANCE REPLACED NP (PROP RPM) GAUGE. (K)