The Left Wheel Departed From The Left Strut. The Airplane Began Sliding On The Turf And Nosed Over

Location: Starbuck, Minnesota Accident Number: CEN23LA227
Date & Time: June 2, 2023, 14:50 Local Registration: N1025T
Aircraft: Kolb Twinstar Aircraft Damage: Substantial
Defining Event: Abnormal runway contact Injuries: 1 Serious, 1 Minor
Flight Conducted Under: Part 91: General aviation - Instructional

Analysis: The flight instructor and the pilot, who was also the builder of the airplane, were practicing soft field landings with the tailwheel-equipped experimental airplane. They performed two threepoint landings to the dry turf without incident. During touchdown on the third landing, with the pilot on the flight controls, the left wheel departed from the left strut. The airplane began sliding on the turf and nosed over, coming to rest inverted. The airplane sustained substantial damage to the fuselage, both wings, and the empennage.

A postaccident metallurgical examination of the left main landing gear revealed that it failed when the left axle fractured from bending overstress consistent with upward forces on the wheel and outward portion of the axle.

It is likely that the pilot executed an improper landing flare, which resulted in a hard landing that fractured the left axle in bending overstress, and a subsequent loss of control and nose over.

Probable Cause and Findings: The National Transportation Safety Board determines the probable cause(s) of this accident to be -- The pilot’s improper landing flare and hard landing, which resulted in the left axle fracturing from bending overstress.

FMI: www.ntsb.gov