As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
ORD INFLIGHT - CREW REPORTED INTENSE BURNING SMELL THROUGHOUT CABIN AT START OF DESCENT AND FOR ABOUT 10 MINUTES. NO VISIBLE SMOKE. CREW WAS UNABLE TO IDENTIFY ORIGIN. LANDED WITHOUT INCIDENT. REPLACED RIGHT PRESSURE REGULATOR VALVE. SYSTEM GROUND CHECKED NORMAL OPERATION.