What was found
SUPPLEMENTAL PACKS SMELL DIRTY, ENGINE BLEEDS SUPPLYING AIR ON TAXI + APU SUPPLYING AIR AT GATE STILL SMELLED UNDER THOSE CONDITIONS. "TRANSFERRED TO NRWC 689-ORD-03890"-C/A-C/W ETN# ETN-EM-72-034, DEFERRED PACK 1. T/S PACK 1 DIRTY SMELL PER FIM 21-20-00-810-801-A TO STEP 36, INSPECTED #1 RECIRCULATION SYSTEM FOUND NO DEFECTS NOTED IAW EMB AMM 21-24-02 REQUIRES FURTHER T/S MEL REMAINS OPEN. REMOVED AND REPLACED PACK VALVE #1 FILTER, OPC LEAK CHECK GOOD, IAW EMB AMM 21-51-01 RAN PACK FOR 2+ HOURS WITH NO SMELL NOTED. MEL RESTORED