Beech E90 N176TW accident near Greenville, Texas

Probable cause

The fatigue failure of the right main landing gear upper torque knee.

NTSB analysis

The pilots were performing an instructional flight with multiple takeoffs and landings when, during one takeoff, the pilots heard a loud noise, and the right main landing gear (MLG) wheel assembly departed the airplane. The pilots elected to perform an emergency landing at another airport due to its larger runways and emergency personnel and equipment. The airplane landed and came to rest upright on the runway surface. Examination of the airplane after landing revealed that the right main wheel/tire and lower shock absorber assembly departed the upper shock absorber assembly. The separated assembly, which was located near the departure airport, impacted the right horizontal stabilizer after separation, which sustained substantial damage.

Metallurgical examination of the assembly revealed that the MLG fractured at the connection between the upper and lower torque knees. Fatigue was identified on a fractured piece of the upper torque knee, and other fractures on the torque knee were consistent with overload. Corrosion assisted in crack initiation, and the crack propagated through fatigue until a critical crack length was reached. It is likely that the fatigue area fractured first and the other connections experienced an increase in loading, which caused them to separate from the MLG assembly.

Text from the NTSB. Open the NTSB docket for CEN19LA166 for the full record.