Narrative:

Ps-1 check was in work by our day shift mechanic. We then changed a nose gear tire that was worn; and proceeded to work the check. I pulled the nose gear pin so we wouldn't forget later to do it. I then went back to the rt main landing gear and lubed the aileron tension regulator in the right main landing gear wheel well and then pulled the gear pin. I then went to the lt wheel well; lubed the left aileron tension regulator and then pulled the lt gear pin and then closed both main landing gear doors. I then took my ladder and laid it on the ground forward of the gear doors; so the ground crew could use it; I then laid the gear pins on the ground at the bottom of the crew stairs so whoever was going up in the plane next could put them away in their spot inside the aircraft. The entire time my mind was on all the things I had to do next; never realizing that I hadn't pulled the center gear pin. I then serviced the eight tires that were slightly low; shipped a bunch of parts; processed the worn tire for shipping and continued the check and paper work. I told my co-worker I had pulled the gear pins and that they were at the bottom of the crew stairs. He was the next to go up on the plane; so he took them up and put them away. We finished the check; the paperwork; processed and shipped all parts and then launched the aircraft. I was notified this morning that the plane flew...with the center gear down; would not retract. They removed the pin and did the appropriate inspection. Looking back; I see that my mind was on all the things I had to do next to get the aircraft ready for its flight; and I didn't give the simple task of pulling the gear pins enough thought; it's a simple task that I was confident that I had accomplished. I should have double checked it and not assumed.

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Original NASA ASRS Text

Title: Maintenance Technician forgot to remove MD11 center gear pin and aircraft flew subsequent leg with center gear down.

Narrative: PS-1 check was in work by our day shift Mechanic. We then changed a nose gear tire that was worn; and proceeded to work the check. I pulled the nose gear pin so we wouldn't forget later to do it. I then went back to the RT main landing gear and lubed the aileron tension regulator in the right main landing gear wheel well and then pulled the gear pin. I then went to the LT wheel well; lubed the left aileron tension regulator and then pulled the LT gear pin and then closed both main landing gear doors. I then took my ladder and laid it on the ground forward of the gear doors; so the ground crew could use it; I then laid the gear pins on the ground at the bottom of the crew stairs so whoever was going up in the plane next could put them away in their spot inside the aircraft. The entire time my mind was on all the things I had to do next; never realizing that I hadn't pulled the center gear pin. I then serviced the eight tires that were slightly low; shipped a bunch of parts; processed the worn tire for shipping and continued the check and paper work. I told my co-worker I had pulled the gear pins and that they were at the bottom of the crew stairs. He was the next to go up on the plane; so he took them up and put them away. We finished the check; the paperwork; processed and shipped all parts and then launched the aircraft. I was notified this morning that the plane flew...with the center gear down; would not retract. They removed the pin and did the appropriate inspection. Looking back; I see that my mind was on all the things I had to do next to get the aircraft ready for its flight; and I didn't give the simple task of pulling the gear pins enough thought; it's a simple task that I was confident that I had accomplished. I should have double checked it and not assumed.

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.