As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
APU SHUTDOWN AFTER AN HOUR OF RUN TIME ON THE GROUND. PUT A PRESSURE GAUGE IN THE FUEL LINE BETWEEN THE FUEL CONTROL AND FUEL ATOMIZER. FOUND FUEL PRESSURE AT 25 PSI WITH A REQUIREMENT FOR 50-60 PSI. REMOVED FUEL CONTROL UNIT AND FOUND DRIVE SHAFT SHEARED. REPLACED THE FUEL CONTROL UNIT AND OPERATIONAL CHECK NORMAL.