What was found
AT THE GATE VERY STRONG PUNGENT SMELL IN CABIN AND COCKPIT (OIL). ACCOMPLISHED TSM 05-50-00-810-831. FOR CABIN ODOR. UPON INSP. FOUND ODOR SOURCE FROM PACK 1&2. ACCOMPLISHED DECONTAMINATION OF THE ECS. IAW AMM 21-00-00. RAN BOTH PACKS ON APU BLEED. NO SIGN OF CONTAMINATION. ALSO ISOLATED PACKS NO SIGN OF CONTAMINATION. INSPECTED PACKS &APU AREA NO SIGN OF POSSIBLE CAUSE. AS PRECAUTIONARY R&R RECIRCULATING FILTER. A/C OK FOR CONTINUED SVC.