What was found
FA REPORTED ODOR OF FUMES AFTER ENG STAR AND 10K FT ON DES. PERFORMED CONDITIONAL INSPECTION AMM 05-51-56-200-801 NO SMOKE OR FUMES DETECTED, FOLLOWED FIM 21 -00 TASK 830 WITH FLIGHT CREW ASSISTANCE ENGINE 1/2 RAN COULD DUPLICATE THE ODOR ON START UP BUT ODOR WOULD DISSIPATED. CONFIRMED ODOR IS NOT PRESENT WITH APU ONLY. INSPECTED RECIRCULATION FILTERS AND FOUND EXTREMELY DIRTY. FILTERS WILL NEED REPLACEMENT AND ENGINES NEED TO BE RAN FOR CONFIRMATION. R & R BOTH RECIRCULATION FILTERS IAW AMM 21-25-01.