ATA 32

Upper Bearing Lock Pin

Pay careful attention to the “UPPER BEARING LOCK PIN” (see graphic) when re-assembling the nose strut. The lock pin’s purpose is to secure the “UPPER BEARING” to the lower strut “PISTON,” and without the lock pin installed, the upper bearing can unscrew itself from the lower strut piston during taxiing and towing operations. If the upper bearing unscrews even a little bit, it will result in the strut lengthening, thus not allowing the nose landing gear to retract completely into the uplock assembly, failing to extinguish the red light in the gear handle. This scenario has happened twice that I know of, and on both occasions, the lock pin was missing from the upper bearing. Luckily, the upper bearing did not completely unscrew itself from the lower strut piston, which could had resulted in a much bigger problem than a red light in the gear handle.