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3.11.8 Break-up of the aeroplane
After the impact of the high-energy objects the aeroplane broke up in the air: There are two distinct phases in relation to the in flight break-up; the break-up of the front fuselage and the centre/rear fuselage. These are described in the paragraphs below.
3.11.8.1 Break-up of the front fuselage
The front fuselage broke into the following three main components:
• the damaged cockpit with a large part of the lower fuselage with the passenger floor in front of STA655;
• large parts of the fuselage above the passenger floor, in front of STA655;
• the cylindrical fuselage part between STA655 and STA888/909.
Within approximately one second the fuselage top parts in front of STA655, above the passenger floor, were bent upward, while the fuselage lower part in front of STA655, was bent downward. This was followed immediately by the fuselage part behind it, bending radially outward and separating behind the doors 2L and 2R at (STA 888/909).
All recovered parts from the fuselage in front of STA888/909, were found on or very close to the locus line. This indicates that the break-up sequence of the forward part of the aeroplane took place immediately after the last FDR recording, and lasted in the order of seconds.
3.11.8.2 Break-up of the centre and rear fuselage
The separation of the forward fuselage resulted in significant changes to the mass and balance and aerodynamic characteristics or the aeroplane, substantially modifying its flight characteristics.
The centre of gravity moved aft, probably behind its rear certified limit, probably causing longitudinal instability of the aeroplane. Further, the aerodynamic loads that would normally result from the air impacting and flowing over the smooth forward fuselage were replaced by the loads created by air impacting and flowing over the blunt open, damaged fuselage, which resulted in increased drag and altered airflow over the inboard sections of the wings.
Despite having no radar data available for trajectory analysis, a general sequential outline of the break-up sequence can be established using wreckage location information in combination with the analysis of fractures between the structural parts. As mentioned before, as no post-crash radar fixes or eye-witness declarations were available, it is not possible to make an accurate reconstruction of the break-up sequence.
The fact that no wreckage pieces from behind STA909 were found in site 1 through 3 suggests that after the front part of the aeroplane broke up and separated, the remainder of the aeroplane continued flight for some time along an undetermined path.
In a relative short time interval, the two wing tips, the stabilizers, the fuselage behind STA 1546.5, inclusive of most parts of the rear pressure bulkhead, separated from the centre fuselage and hit the ground in site 4. The centre fuselage section with the remainder of the wings and engines continued their flight for some time as they were located in site 6. Later in time, the fuselage part aft of STA 1546.5 broke near the rear pressure bulkhead. The main parts behind it, the vertical fin, the centre stabilizer torsion box and the damaged tail cone landed very close together at site 5.
In site 4 several textile rolls were identified on satellite imagery and were, later on, recovered from the site. From the cargo manifest it was established that 10 textile rolls were transported in a container in the aft cargo compartment located at position 33L. The textile rolls were found in close proximity of (500 metres) or on top of other wreckage pieces. The textile rolls possessed a very low ballistic coefficient.
The parts found in sites 4 had big differences in Ballistic Coefficients and they were found in close proximity. This suggests the break-up in this site was at a much lower altitude and thus later in the break-up sequence than the first break-up.
This is furthermore substantiated by the wreckage area footprint and spread of the wreckage pieces in sites 4 through 6. For sites 4 through 6 the maximum range the wreckage pieces are spread is approximately 1.5 kilometres from the main impact point in site 6; this is substantially less than the wreckage spread of 7 kilometres for sites 1 through 3. In site 4 the left and right wing tip were located but the remainder of the left and right wings were found in site 6.
Also the left and right horizontal stabilizers were found in site 4. The left stabilizer was found on the right hand side of the expected flight track, the right stabilizer on its left side. This suggests that at this point the aeroplane may have been inverted. The stabilizer centre torsion box was found in site 5. This suggests that the stabilizers separated at the same moment as other parts found in site 4, while the aft tail section continued its flight for a short time.
In site 5 the vertical fin was located and in close proximity parts of the tail section. The crew bunk container, located in the aeroplane aft cargo compartment (hold 31 and 32), was located in site 5.
Other cargo items from load positions 41 to 44 (See Appendix E) were found spread over sites 4 and 5. These items were found in reverse, meaning that the items that originate from the left hand side of the aeroplane were found predominantly on the right hand side of the expected flight track and vice versa. This combined with other wreckage pieces suggest that at this point the aeroplane may have been inverted.
In site 6 a fuselage part just in front of passenger door 3R was found under the aeroplane keel beam structure together with a part of the lower fuselage, normally located just in front of the centre wing. This suggests that the centre fuselage with the remainder of the wings and engines was in an upside down position by a rotation around the lateral axis, and thus moving in a rearward direction, during impact with the ground. Both wings were found separated from the mid centre section, up-side down in site 6. The engines did not separate in the air as both engines were found in site 6 in close proximity of their respective wing positions. However, the left engine intake ring was found in site 2. This indicates an earlier separation in time of that part.
With the available information the conclusion can be drawn that after separation of the front fuselage, the centre and aft fuselage sections with the complete wings continued flying, and then after a short time interval the wing tips broke off and the aft fuselage section and tail separated. Thereafter the aft fuselage section may have rolled inverted when the stabilizers separated, and later the damaged tail section, with the vertical fin and the stabilizer centre torsion box, separated near STA2150. These parts landed closely together. From the wreckage pattern it can be seen that this would have been at a low altitude. The centre fuselage finally landed in an inverted position after a rotation around its lateral axis.
The time interval between the separation of the front fuselage and the moment that the remainder of the aeroplane impacted the ground is estimated to have been 1-1.5 minutes.
Findings
• From the ballistic trajectory analysis it can be concluded that all the pieces of wreckage from the fuselage parts in front of STA888/909 departed the aeroplane immediately after the last Flight Data Recorder recording.
• It also indicated that all debris recovered from the other three sites (4, 5 and 6), departed the aeroplane later, as their location in the debris field was relatively far beyond the locus line.
• After separation of the front fuselage, the remainder of the fuselage with the complete wings continued its flight.
• After a short time interval the wing tips broke off and the aft fuselage section with the tail separated.
• Thereafter the aft fuselage section may have rolled inverted when the horizontal stabilizers separated, and later the damaged tail section, with the vertical stabilizer and the stabilizer centre torsion box, separated near STA 2150.
• The centre fuselage finally landed in an inverted position after a rotation around its lateral axis.
• The time interval between the separation of the front fuselage and the moment that the remainder of the aeroplane impacted the ground is estimated to have been 1-1.5 minutes.