What happened
While taxiing for takeoff at McGrath, Alaska, the pilot of the aircraft experienced a deflation of the left, over-sized Tundra tire. This deflation caused the left wing to subsequently strike the ground.
The pilot had been involved in a separate accident with the same airplane one week prior, when the main landing gear collapsed during a landing at a rural mining airstrip. Following that initial incident, the pilot performed unauthorized repairs to the wing lift struts and the landing gear. Specifically, the pilot fashioned a main gear leg using iron water pipe and used tape to attach boards to the lift struts.
The pilot intended to fly the aircraft to Palmer, Alaska, to obtain proper repairs. During the flight, an interim stop was made at McGrath for refueling; however, no repairs were sought from an aviation repair facility prior to the attempted departure that resulted in this accident. The pilot was not injured.
The investigation
Investigators examined the landing gear and tire assembly. Discussions with Tundra tire experts revealed that maintaining proper landing gear geometry is essential for safe flight operations. If the geometry of the landing gear is incorrect, it can create additional side loads on the tire. These loads may cause the tire to rotate on its rim, which can slice the valve stem and lead to tire deflation.