As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
(LOG 9271896) ON SVC FOUND BURNING SMELL IN FLT DECK WITH APU BLEED ON. FOUND DEBRI IN PLENUM. R/R RECIRC FAN FILTERS IAW B737 AMM 21-25. RAN ENGINES WITH PACKS AND NO ODOR WAS DETECTED. AIR CONDITIONING OPS CHECK GOOD IAW B737 AMM 21-00.