As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
LEFT IDG DISCONNECTED AND APU WOULD NOT START IN-FLIGHT AFTER 3 ATTEMPTS. FLIGHT DIVERTED TO SLC. SUPPLEMENTAL DATA UPDATE: REPLACED IGNITION EXCITER, IGNITION PLUG, AND LEAD. OPERATION CHECKS NORMAL. IGNITION EXCITERS ARE BEING UPGRADED PER OEM 49-41-09, TO IMPROVE HIGH ALTITUDE STARTS.