What happened
During a night landing under visual meteorological conditions, a McDonnell Douglas MD-11F freighter was being operated by a crew consisting of a pilot-in-command in the right seat and a captain in the left seat receiving initial operating experience. The aircraft was landing on an 8,579-foot-long concrete runway. Following the touchdown of the main landing gear, the nose gear made contact with the runway and subsequently collapsed.
The investigation
Analysis of data from the flight data recorder showed that after the main gear touched down, the control column was moved sharply forward. This action changed the pitch angle from approximately 5 degrees nose up to about 1 degree nose down, which was accompanied by a reduction in load factor to approximately 0.3 g's. Upon contact of the nose wheel, the vertical load factor spiked to approximately 2.5 g's, which was more than twice the load factor of a typical landing and included an excessive load factor increment of 0.75 g's.
Findings
- The aircraft sustained damage to the area around the pressure bulkhead at station 625.
- A metallurgical examination of the nose landing gear assembly remnants showed that the failure was consistent with overstress.
- No evidence of preexisting fractures was found in the nose gear components.