Some Mechanical and Structural Aspects of the Smolensk Crash
By Dr. Gregory Szuladzinski, Ph.D., MSME
SCND2014GS

1. General Course of Events

Fig. 1. The outline of the Soviet-made Tu-154M Part of the left and right wing, a widened section adjacent to the fuselage and is often called the center wing. This section passes here through the cabin and is, in itself, very solidly built. In most air accidents, when the machine somehow hits the runway, this part is the least damaged in comparison with the tips of the wings or ends of the hull.

Above: Fig. 2. The aircraft trajectory, according to recent studies, is indicated by a black line. The upper graph shows it in a plan view, and lower in elevation. The TAWS point (later referred to as critical point, in short: the point K) is the place where the direction of the flight has significantly changed. The nearly vertical lanes on theupper photograph are Gubienki (right) and Kutuzova Street (left).

As per above, point TAWS (TAWS # 38 according to the NTSB report (Annex 4 to the report KBWL)) will be called a critical point, point K. (The plan view of the trajectory in Figure 2 is a simplification. The last section between point K and FMS really is an arc tangent to the previous segment. This means that the aircraft was turning).

Point FMS indicates the location where the on-board computer (Flight Management System) memory suffered a power failure. Therefore, contact with the ground was lost. This aircraft has multiple protections against the power drop, so that the event leading to this had to be very serious. Barely visible small squares with the words "wing" and "stabilizer" are the places where the aircraft components were found. "Birch" refers to a tree, which was considered a direct cause of the crash. It has been hypothesized that hitting the birch tree resulted in the loss of the wing, and the general stability, which resulted in crashing to the ground.

To investigate this issue, prof. Binienda of Acron University presented simulations employing FEA (Finite Element Analysis) and showed that, with appropriate speed, the wing was able to cut the birch, not vice versa. We must mention that in photos the birch looks like it was cut by a blunt object, but its relationship to the accident is difficult to determine.

More detailed trajectory studies accomplished in the meantime show that any contact between an airplane and this tree was not possible. This, however, does not preclude the role of other trees in the whole event.

The plane crashed into the ground near the point of FMS.