As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
APU REPORTS SHOW A RAPID SPIKE IN CT5ATP TEMP. CT5ATP TEMP IS AT OR ABOVE THE THRESHOLD 605 DEGREES. INSTALLATION TASKS MAY AFFECT APU ON DEMAND IN-FLIGHT START CAPABILITY. UPON COMPLETION CONTACT MAINTENANCE CONTROL AND REPORT THAT THIS TASK HAS AFFECTED APU IN-FLIGHT START CAPABILITY. GROUNDED - YES. REMOVED AND REPLACED APU. REF AMM 49-11-00 ACCOMPLISHED APU INSTALLATION TEST, OPS TEST AND BITE TEST. APU EXISTING FAULT FOUND.