What was found
FUME EVENT ON APPROACH CREW WENT ON O2. -REF TSM 05-50-00-810-831A APU VERIFIED NO LEAKS. PRE-CONDITIONES A/C W/APU NO SMELL NOTED. ISOLATED PACK 1+2 NO SMELL NOTED, RAN ENGINES + ISOLATED BLEEDS, NO SMELL NOTED. ALL STEPS ACCOMPLISHED W/ GEROTRACER ON BOARD. REF AMM 21-61-00-49-00-00,71-00-00. A/C OK FOR SERVICE.