What was found
BURNING ODOR, FL250, SMOKE ODOR IN ACFT, VERY FAINT ODOR BRIEFLY THEN DISAPPEARS, OCASIONALLY REAPPEARS. IAW MM 05-51-58-800, RAN BOTH PACKS INDIVIDUALLY & TOGETHER WITH BOTH ENGINES & APU, REMOVED BOTH OZONE CONVERTERS, INSPECTED INSIDE & REINSTALLED, CONFIRMED NO BREAKERS OPEN IN E & E, PUT ACFT IN AIR MODE TO RULE OUT SUPPLEMENTAL HEATER FOOT & SHOULDER HEATERS. NO DEFECTS NOTED, LEAK CHECKED OZONE CONVERTERS. R & R FOUR LOWER RECIRC FILTERS IN FWD CARGO. R & R FOUR RECIRCULATION FILTERS IN UPPER CABIN, RAN LT & R PACK UNITS, LT 10 MINUTES, RT 10 MINUTES & BOTH FOR 10 MINUTES, THE SLATE ODOR IS STILL PRESENT BUT VERY FAINT. R & R LT OZONE CONVERTER. RAN APU WITH BOTH PACKS ON, THEN RAN PACKS INDIVIDUALLY. NO BURN ODOR. ACCOMP EXTENDED ENG RUN BOTH LT & RT ENGS, CYCLED PACKS & BLEEDS WITH DIFFERENT TEMP SETTINGS TO INDUCE AN ODOR. SHUTOFF APU ENTIRELY & RAN SYS THE SAME WAY WITH NO ODORS NOTED. R & R RIGHT OZONE CONVERTER, NO BURN ODOR NOTED IAW LP 7865739 AND 7854182.