 Special three-wheeled trailers were built and the aircraft were driven to Moscow, but the flypast was cancelled because of bad weather.The tests conducted in preparation for the parade revealed a number of flaws in the design including poor directional stability, a cramped cockpit without heating or ventilation, poor access to the engine, inadequate fuel capacity, compounded by the lack of a fuel gauge, and poor elevator control forces.Five aircraft were modified to correct these issues before resuming the factory's testing in late 1946.