Narrative:

Pulled into gate and set parking brake and shut down #3 engine. Waited shortly for external power and when we got it I connected to it then shut down #1 engine. I then did the shutdown checklist; did debrief; discussed strange taxi in; used restroom; and left the aircraft. There was no crew bus so the first officer went up to cockpit to call for one and saw that fuel lever was still up. He shut off #2 and came back down to ramp and informed me that the engine was still running when he went up to cockpit.I rarely taxi in on three engines and in this case did just that. I went through my normal shutdown habit pattern which is just shutting down one and three. I missed it on the shutdown checklist because I didn't actually look at the levers because; in my mind I was convinced I had shut them down. Visually check everything on the checklist because it will help when your habit pattern is broken.

Google
 

Original NASA ASRS Text

Title: MD-11 flight crew inadvertently left Number Two engine running at the gate.

Narrative: Pulled into gate and set parking brake and shut down #3 engine. Waited shortly for external power and when we got it I connected to it then shut down #1 engine. I then did the Shutdown Checklist; did debrief; discussed strange taxi in; used restroom; and left the aircraft. There was no crew bus so the First Officer went up to cockpit to call for one and saw that fuel lever was still up. He shut off #2 and came back down to Ramp and informed me that the engine was still running when he went up to cockpit.I rarely taxi in on three engines and in this case did just that. I went through my normal shutdown habit pattern which is just shutting down one and three. I missed it on the shutdown checklist because I didn't actually look at the levers because; in my mind I was convinced I had shut them down. Visually check everything on the checklist because it will help when your habit pattern is broken.

Data retrieved from NASA's ASRS site as of July 2013 and automatically converted to unabbreviated mixed upper/lowercase text. This report is for informational purposes with no guarantee of accuracy. See NASA's ASRS site for official report.