What was found
FLT#1433, MCO-SJU. 'DESCENDING THUR FL200 FO SMELL DIRTY SOCKS SMELL. CA NOTICE IT AROUND 17000 FEET, IT WAS A MILT BUT PERSITING ODOR. WE TENT TO THINK IT WAS A LVL 1 ENV.SYST ODOR. INFLIGHT DIDNT SMELL IT. WE RAN DID ESOLATION CHECK AND COULD TELL A DECREASE IN ODOR WITH PACK 1 OFF. NO ONE IN THE CREW EXPERIENCE ANY PHYSIOLOGICAL EFECTS, NOR ANY CUSTOMER COMPLAINS; COMPLIED WITH INFO NOTICE 2017-T015 SECTION A ISOLATED TO FAULT TYPE 1 (APU). PERFORMED LEVEL A DECONTAMINATION PER AMM 21-00-00-615-802A R/R HEPA FILTERS. NO ODOR PRESENT AT THIS TIME.