Amateur-built STOL CH701 N324WS accident near Ambler, Alaska

Probable cause

The pilot’s improper decision to take off from unsuitable terrain, which resulted in impact with uneven terrain, the subsequent failure of the nosewheel fork, and a nose over.

NTSB analysis

The pilot, who was also the owner and builder of the experimental amateur-built airplane, reported that he landed the airplane on sand dunes. Forty-five minutes later, he took off from the sand dunes, and during the takeoff roll, the airplane hit some bumps. Just before the airplane reached rotation speed, it hit a larger bump, which propelled it upward. The airplane then descended in a nose-high attitude and impacted terrain, followed immediately by the nose landing gear (NLG) collapsing. Subsequently, the airplane nosed over and came to rest inverted.

Postaccident examination of the airplane revealed that the rudder and both wing struts sustained substantial damage. The nosewheel fork had separated from the nose strut in three fragments at two fracture locations, one on each side of the nose strut attachment. Examination of the fracture surfaces revealed that all the fractures exhibited features consistent with overstress fracture in upward bending of the nosewheel fork. No evidence of preexisting cracks, wear marks, or corrosion was found. The pilot reported that the accident may have been prevented if he had conducted a more “detailed” inspection of the takeoff area. Given the evidence, it is likely that, during the takeoff roll, the NLG impacted uneven terrain, which led to the airplane becoming airborne in a nose-up attitude and then impacting terrain with force that exceeded the nosewheel fork’s structural capabilities and resulted in the nosewheel fracturing.

Text from the NTSB. Open the NTSB docket for ANC20LA053 for the full record.