As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
ASH 7367 IAD - CREW REPORTED APU SHUT DOWN WITH BURNING SMELL AND SMOKE. MX REPORTED THE STARTER BURNT UP CAUSING THE SMELL. MX REPORTS THE APU START CONTACTOR IN JB-5 IS BAD AND THE STARTER IS BURNED BECAUSE OF THE CONTACTOR. MX DISABLED THE START CONTACTOR AND DEFERRED THE APU.