WPR23LA340

The pilot stated that when he touched down, the main landing gear contacted the runway surface, followed by the nose gear. He instantly heard a loud “bang” as the nose gear collapsed and the nose continued to settle, sliding down the runway surface. Examination of the nose gear revealed that the nose landing gear actuator failed due to the buckling and fracture of the ball screw, which resulted from compressive loads on the actuator assembly. These compressive loads were likely from vertical and/or aft loads on the nose wheel. The actuator was likely in the fully extended position, but the length of the accident actuator was longer than its design length at full extension. Issues with the actuator installation that might have contributed to the overextension could not be determined. The examination further revealed that the nose landing gear likely sustained a relatively hard landing while in the fully extended position. However, the additional length in the overextended actuator assembly made the ball screw susceptible to buckling failure from lower compressive loads than designed. Additionally, since less length of the extension tube was constrained by the housing in the overextended assembly, the reduced constraint likely made the assembly susceptible to buckling at even lower loads. The assembly’s extension beyond its design length likely contributed to the failure, as the extension would have diminished the safety margin and increased the vulnerability to buckling failure under high landing loads.

On September 5, 2023, about 1620 Pacific daylight time, a Rutan Long-EZ experimental airplane, N58JB, was substantially damaged when it was involved in an accident near Bullhead City, Arizona. The private pilot, the sole occupant, was not injured. The airplane was operated as a Title 14 Code of Federal Regulations Part 91 personal flight. The pilot stated that he entered the traffic pattern for runway 16 and made a normal approach. Upon touchdown, the main landing gear contacted the runway surface, followed by the nose gear. He instantly heard a loud “bang” as the nose gear collapsed and the nose continued to settle, sliding down the runway surface. The airplane veered left, and the pilot applied the right brake in an attempt to regain directional control. The airplane continued to the left off the runway and the front canard collided with a runway sign. The airplane came to rest on the gravel adjacent to the runway. The EZ NoseLift NL1-12 nose landing gear actuator ball screw assembly was sent to the NTSB Materials Laboratory for examination. The ball screw exhibited bending and fractures at two locations. The ball screw deformation was particularly evident near the bearing at the aft end and in the opposite direction at the fracture locations near the forward end. Fracture features associated with the ball screw displayed matte gray features on slant angles, consistent with buckling deformation and overstress fracture. No preexisting cracks were detected. The forward end of the extension tube housing for the ball screw assembly was fractured and splayed outward, with fracture surfaces consistent with ductile overstress fracture on slant angles. Contact marks on the interior surfaces, along with deformation patterns and contact marks, were consistent with off-axis contact between the housing and the extension tube. The total length of the ball screw assembly between the attachment points at the time of fracture was determined by adding the lengths of the fractured pieces, and the total length was estimated to be 17.41 inches. For comparison, an engineering drawing for the EZ-Noselift NL1-12 for installation on the Long EZ aircraft measures 16.711 inches between the forward and aft attachment hole centers when fully extended.