As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
APU FAILED IN FLIGHT, WOULD NOT RESTART ON GROUND. REPLACED SPEED SENSOR AND CONTROLLER, NO HELP. APU HANGS AT 20 PERCENT WITH SPARKS OUT OF TAILPIPE SUSPECT TURBINE FAILURE. REMOVED AND REPLACED APU ASSY PER M/M. OPS / LK CK OK. MCO/PLAC REMOVED.