B737 Undifferentiated or Other Model
Flight Crew Instrument; Flight Crew Air Transport Pilot (ATP); Flight Crew Multiengine
Aircraft Equipment Problem Less Severe; Deviation / Discrepancy - Procedural Published Material / Policy; Ground Event / Encounter Other / Unknown
Flight Crew Returned To Departure Airport; General Maintenance Action
Aircraft; Human Factors; Procedure
A 4th gear pin was discovered installed after takeoff in the nose gear. Performed return and landed uneventful. Pin was removed and flight resumed to destination. The aircraft had just returned from several days of maintenance. At some unknown point; someone installed a nose gear pin that had no ribbon or markings. Using standard gear pins with proper markings would have prevented this occurrence.
B737 Captain reported takeoff with an unknown nose gear pin resulted in a return to the departure airport.