Incident Overview
During the landing gear extension procedure, the pilot heard a loud bang emanating from the nose of the airplane. While both main landing gear extended normally, the nose landing gear failed to deploy. The pilot subsequently executed the emergency landing gear checklist but was unable to extend the nose gear.
ATC Confirmation and Landing
Personnel in the air traffic control tower confirmed that the nose landing gear had not extended after the pilot performed two flybys. The pilot then executed a landing using only the main landing gear, allowing the aircraft to settle onto its nose as airspeed bled off. The airplane came to rest approximately 2,000 feet down the runway.
Post-Accident Examination
A post-accident examination of the landing gear system revealed a fractured adjusting bellcrank at its upper end, where the fork bolt is normally inserted. The fracture features were consistent with overstress, and no evidence of preexisting damage was found. The deformation and fractures appeared consistent with the bellcrank rotating relative to a stationary fork bolt during nose gear extension. Such a scenario could occur as a result of some obstruction or binding in the linkage forward of the bellcrank. However, the nature and cause of the binding in the linkages could not be determined.
Conclusion
The investigation identified the fractured adjusting bellcrank as the primary mechanical failure, with overstress fractures and no preexisting defects. The specific reason for the binding that likely led to the fracture remains unknown.