FLC OF AN MLG FORGOT TO SHUT DOWN 1 ENG AFTER GATE ARR AND DEPLANING. A MECH FOUND THE ERROR AND SHUT OFF THE ENG AND RECORDED THE ACTION IN THE ACFT LOGBOOK.

Narrative

AS I TAXIED TO THE GATE I REMEMBER LOOKING UP TO SEE IF THE APU WAS RUNNING AND IT HAD JUST COME ON THE LINE. I PLACED THE APU BUS SWITCHES TO ON AND SECURED THE R ENG WHILE WAITING FOR PARKING PERSONNEL. AFTER SETTING THE PARKING BRAKE; I SECURED THE L ENG. I CALLED FOR THE PARKING CHKLIST WHILE GETTING THE 'CHOCKS IN' SIGNAL AND THE EXTERNAL PWR AVAILABLE SIGNAL FROM GND PERSONNEL. I RESPONDED TO THE CHKLIST WHILE I WAS PUTTING THE EXTERNAL PWR ON THE ACFT AND SHUTTING DOWN THE APU. THE LEAD FLT ATTENDANT ENTERED THE COCKPIT DURING THIS TIME FRAME SEEKING INFO ON THE ACFT SWAP AND ASSOCIATED 'QUICK TURN' THAT WE WERE TOLD TO EXPECT. TO THE BEST OF MY MEMORY; THE FO READ THE PARKING CHKLIST AND I RESPONDED TO IT. I WAS SOMEWHAT PREOCCUPIED WITH THE PARKING PROC AT XA; THE GND PERSONNEL BEING SLOW; THE APU BEING LATE; A GATE CHANGE REQUEST; AN ACFT SWAP AND A MAINT PROB ON THE L ENG THAT I NEEDED TO SPEAK TO MAINT ABOUT. THE FO WAS PREOCCUPIED WITH THE ACARS DUMPING ITS PROGRAM; HAVING TO RESPOND TO OPS WITH CORRECT TIMES; NOTIFYING DISPATCH OF THE CORRECT TIMES AND INFORMING THE FLT ATTENDANTS OF THE LAST MIN ACFT SWAP. TO THE BEST OF MY MEMORY; I SHUT DOWN BOTH ENGS AND CORRECTLY RESPONDED TO THE PARKING CHKLIST; MAINT RPTED THAT THE R ENG WAS LEFT RUNNING. SUPPLEMENTAL INFO FROM ACN 380997: THE MECH SHUT DOWN THE ENG AND MADE A LOGBOOK ENTRY.