Narrative:

The center main landing gear pin was left in place following a 'B' maintenance check at the air carrier hangar at ZZZ airport. I observed another mechanic closing the center gear door and did not see the landing gear pin or pin flag. I 'assured it was removed.' the taxi crew that took the aircraft to the gate and the flight crew both assumed the pin was removed. It was not until the aircraft was in-flight before the problem was discovered. Normally a long center gear pin is used at this particular check, that is, a pin with an arm and release lever approximately 3 ft long that protrudes below the doors and can be seen with the doors closed. During this particular check, a standard short gear pin was used and could not be seen with the doors closed without standing on the truck assembly.

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Original NASA ASRS Text

Title: AN MD11 RETURNED TO THE FIELD DUE TO AN INABILITY TO RETRACT THE CTR MAIN LNDG GEAR, CAUSED BY A GEAR PIN NOT BEING REMOVED AFTER MAINT.

Narrative: THE CTR MAIN LNDG GEAR PIN WAS LEFT IN PLACE FOLLOWING A 'B' MAINT CHK AT THE ACR HANGAR AT ZZZ ARPT. I OBSERVED ANOTHER MECH CLOSING THE CTR GEAR DOOR AND DID NOT SEE THE LNDG GEAR PIN OR PIN FLAG. I 'ASSURED IT WAS REMOVED.' THE TAXI CREW THAT TOOK THE ACFT TO THE GATE AND THE FLC BOTH ASSUMED THE PIN WAS REMOVED. IT WAS NOT UNTIL THE ACFT WAS INFLT BEFORE THE PROB WAS DISCOVERED. NORMALLY A LONG CTR GEAR PIN IS USED AT THIS PARTICULAR CHK, THAT IS, A PIN WITH AN ARM AND RELEASE LEVER APPROX 3 FT LONG THAT PROTRUDES BELOW THE DOORS AND CAN BE SEEN WITH THE DOORS CLOSED. DURING THIS PARTICULAR CHK, A STANDARD SHORT GEAR PIN WAS USED AND COULD NOT BE SEEN WITH THE DOORS CLOSED WITHOUT STANDING ON THE TRUCK ASSEMBLY.

Data retrieved from NASA's ASRS site as of July 2007 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.