About ten minutes into the flight, the pilot initiated a pull toward the vertical with about 360 km/hr and 7 Gs, according to witnesses. This would have been well within the maximum airspeed and load specifications of 450 km/hr and 10 Gs, respectively. The right wing of the airplane separated during the pull up. ... Testing of the wing spar was performed by the NTSB and MAK (Russian Investigative Authorities). Both agencies found numerous voids in the composite spar caps. The investigation revealed evidence that the curing process for the wing spar did not provide adequate vacuum pressure. There was evidence that during the curing process, the fibers separated from each other, which resulted in voids in the final composite material.