What was found
DIRTY SOCK SMELL ON TAKE OFF, PACK 1 OFF AND SMELL DISSIPATED. DESCRIPTION OF ODOR/FUMES: PERSISTENT, MUSTY DRY SMELL. APPARENT CABIN SOURCE: UNKNOWN. NO VISIBLE SMOKE/HAZE. NO MEDICAL ATTENTION REQUIRED. -REF TSM 05-50-00-810-831A . APU VERIFIED NO LEAKS. PRE-CONDITIONED A/C WITH APU, NO SMELL NOTED. ISOALTED PACK 1 AND 2, NO SMELL NOTED. RAN BOTH ENGINES AND ISOLATED BLEED PACK 1 AND PACK 2, NO SMELL NOTED. ALL STEPS ACCOMPLISHED WITH AEROTRACER ON BOARD. REF AMM 21-61-00-49-00-00. SMELL COULD NOT BE DUPLICATED. A/C OK FOR SVC.