As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
AFTER PUSHBACK AND BOTH ENGINES STARTED, RECIEVED NOTIFICATION FROM FROM FA LOCATED IN AFT CABIN THAT THERE WAS THE ODOR OF SMOKE. DURING THIS TIME A HIGH PITCH NOISE WAS HEARD THROUGHOUT CABIN. ENGINE SHUTDOWN AND NOISE ENDED. RAN BOTH ENGINES AND OPERATED HYDRALIC SYSTEM AND OPERATED AC PACK SYSTEM INSPECTED ALL SYSTEMS FOR SIGNS OF SMOKE OR ODOR. NO DEFECTES NOTED AT THIS TIME.