Analytical Service Pty Ltd 10 Coolawin Rd, Northbridge 2063, Australia tel. (061) (2) 9967-0998 e-mail: [email protected] ANALYTICAL SERVICE Pty Ltd Report No. 456 SOME MECHANICAL AND STRUCTURAL ASPECTS OF THE SMOLENSK AIR CRASH by Dr. Gregory Szuladzinski, MSME Independent Technical Advisor to Parliamentary Committee for Investigation of the Catastrophe of the TU-154 M on April 10, 2010 ©Analytical Service Pty Ltd This is a translation of the corresponding document in Polish Version 6 May 2012 1 - 35 Analytical Service Pty Ltd Table of Contents Introduction.................................................................................................................................................... 3 Summary of Results ...................................................................................................................................... 3 1. General Course of Events ........................................................................................................................ 4 2. Anticipated and Real Structural Damage, Comparison ........................................................................... 6 3. What Happened near Point K? .............................................................................................................. 12 4. More about the fate of the left wing ........................................................................................................ 13 5. Kinetics of Last Phase of Flight .............................................................................................................. 15 6. Explosion in the Fuselage. ..................................................................................................................... 18 7. Separation of the Tail Section of Fuselage ............................................................................................ 24 8. Other Possible Considerations of this Accident ..................................................................................... 25 9. Mortality in air accidents ......................................................................................................................... 25 Appendix I. Collision of the Wing with a Tree (birch) .................................................................................. 25 Appendix II. Fragmentation ......................................................................................................................... 26 Appendix III. Fuel in Special Circumstances............................................................................................... 31 Appendix IV. Mechanics of HE Explosion and Aircraft Fire ........................................................................ 31 Appendix V. Aircraft Rotation around the Longitudinal Axis ....................................................................... 32 Appendix VI. Eyewitness Accounts ............................................................................................................. 33 Appendix VII. Other Incomprehensible Issues ............................................................................................ 34 Conclusions ................................................................................................................................................. 34 Picture sources: .......................................................................................................................................... 35 Other Work of This Company...................................................................................................................... 35 Technical questions related to this Report should be directed to the Parliamentary Group A. Macierewicza. After sorting (to avoid repetition) questions will be forwarded to the author to answer. ..... 35 2 - 35 Analytical Service Pty Ltd Introduction The incident took place in the Russian Federation on April 10, 2010, when the plane, a Tu-154M, owned by the Government of Poland attempted to land in Smolensk. On board there was the President of Poland, Dr. Lech Kaczynski, with his wife and many VIPs, a total of 96 people. Most of them were his closest staff, commanders of Polish armed forces, president of the central bank and leaders of Sejm, the Parliament of Poland. All of them including the flight crew died as a result of this accident. In view of the known facts the purpose of the following analysis is to determine the physical reasons that lead to the catastrophe. The available data are: The number and the size distribution of the fragments found after the crash along with some navigation data. Most of the information and photographs were made available by the Polish Parliamentary Committee for Investigation of the Crash and from Dr. Kazimierz Nowaczyk and Dr. Wieslaw Binienda, experts of the Committee. A substantial amount of data was provided by Marek Dabrowski, MSAE. A quantitative analysis of the spread of the debris is not undertaken in this report. Summary of Results The destruction of the plane was initiated while it was still airborne, approaching landing. One explosion took place in left the wing, at about one-third length from the fuselage. This had a strong local effect on the wing, causing its split into two parts. A secondary effect was partial damage to other major structural connections. A second explosion took place inside the fuselage. It caused massive destruction and fragmentation of the fuselage into several major parts and hundreds of smaller pieces. The landing itself (or fall) in the wooded area, no matter how adverse, and at what angle, could not in any way result in fragmentation to the documented extent. 3 - 35 Analytical Service Pty Ltd 1. General Course of Events 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. Fig. 1. The outline of the Soviet-made Tu-154M 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 the upper photograph are: Gubienki Street (right) and Kutuzova Street (left). 4 - 35 Analytical Service Pty Ltd 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. 5 - 35 Analytical Service Pty Ltd 2. Anticipated and Real Structural Damage, Comparison In the vicinity of point K a sudden event took place causing a change in course. (TAWS, Figure 2). The altitude was greater than 30 m and horizontal speed - about 270 km/h. Trees and forest undergrowth at the emergency landing area, had a tendency to reduce the horizontal velocity. ("Emergency landing" is used here as a loose term, meaning contact with the ground, no matter how undesirable the circumstances.) Elastic properties of the soil should act somewhat like a shock absorber, reducing the peak vertical acceleration of the fall. There were no obstacles in addition to trees, which could have significantly slowed down the machine. The effect should not be much larger, then then driving a car into the shrubbery of a grove at a speed of 150-250 km/h, which is the estimated speed at the time of impact. (At such a supposed grove, thin trees would need to be quite thin, as we compare the plane of a length of about 50 m to a car, less than 5 m). What should be expected in such a case? As for the plane, the skin would be broken at places and much crumpled sheet metal would result. The wings could be badly broken, but the fuselage should have only a limited breaks and locally damaged areas. Actual photos of the wreckage of the plane shown in Figure 3 and Figure 4