What was found
SMELL OF BURNING CRAYONS AND EXPIRED MILK OBSERVED BY CREW DURING RIGHT START FOLLOWED BY OBSERVED HAZE / PERFORMED AIRCRAFT ENGINE RUN FOR ABNORMAL SMELL, OPERATED LH AND RH A/C PACKS FROM FULL HOT TO FULL COLD TO MID TEMP FOR ANY ABNORMAL SMELLS, IAW CRJ 900 AMM 21-50-00-862-809 AND OPERATIONAL CHECKS CRJ 900 AMM 21-51-00-710-801. NO ABNORMAL SMELLS WERE DETECTED DURING CHECKS, AS WELL WITH LH AND RH PACKS OFF NO ABNORMAL SMELLS WERE DETECTED BY MAINTENANCE IN COCKPIT OR PASSENGER COMPARTMENT.