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APPENDIX A : EXAMINATION OF FLIGHT DATA RECORDER RACK A.1 Background The flight data recorder (FDR) was dislodged from its rack, and was found on the floor of the rear fuselage of Airbus A340-541 A6-ERG (Figure A1). The FDR and associated rack were examined at the Australian Transport Safety Bureau laboratory. Figure A1: FDR and rack as found on-site A.2 Physical examination The FDR was normally secured in the rack with two attachment hooks on the front of the unit. The fasteners used for securing the FDR are known as positive self locking retainers, and work on a spring loaded mechanism (Figure A2). The knurled outer sections of the fastener are placed over the hooks on the front of the FDR, and then tightened via the internal nut to lock it in position. The spring forces the lower section to lock onto the top segment (closest to the rack) which cannot rotate around the rod. The fastener is loosened by pulling on one side of the outer casing, to release the locked mating faces, allowing for the threaded nut to be undone. - 103 - Figure A2: Schematic diagram showing the orientation of rack/FDR in aircraft Flight data recorder Examination of the FDR revealed it to be in a generally good condition. Evidence of minor dents and scratches were observed at a number of locations on the outer surfaces of the recorder. These markings were consistent with the FDR’s contact with surrounding objects following its separation from the rack. The front hooks were in good condition, with no evidence of deformation or mechanical damage. Some paint had been removed in the area adjacent to the right attachment hook. FDR rack The following identification markings were observed on the label on the rear of the FDR rack; TRAY PN 404-050L1DPX2-1 SN 2143 - 104 - On-site photographs (Figure A3) indicated that the left fastener (as viewed from the front of the rack) was slightly less engaged than the right. On the left, a total of 18 threads were visible from the top of the threaded rod to the intersection point with the top nut, while 14 threads were visible on right. Figure A3: On-site photograph showing the original position of the threaded fasteners following the occurrence Examination of the FDR rack revealed moderate plastic deformation towards the front end of the rack, that is the end facing the rear of the aircraft (Figure A4). Figure A4: FDR rack as received The upper shelf of the rack had deformed upwards, and some distortion across the width of the rack was also observed (Figure A5). The heads of the screws holding the upper tray in position had been pulled through their recesses. - 105 - Figure A5: Magnified views of the damaged end of the FDR rack Plastic deformation was also observed on the underside of the upper tray in the areas adjacent to the fasteners (Figure A6). Note the plastic deformation appeared to have affected the upper tray of the rack only, displacing it upwards and outwards. No contact marks were evident on the underside of the rack or fasteners. Figure A6: Underside of rack showing deformation in the region adjacent to the fasteners A number of dimensional checks were performed on the rack. The length and base plate width measurements were generally consistent with the engineering diagram provided by the manufacturer . The height of the upper tray was also measured in several locations, with a permanent deformation of approximately 14mm recorded towards the front. Width measurements were taken at several locations along the upper tray and a variation observed along the length. The left fastener was damaged, with the bottom section (including the spring and the circlip used to hold the spring in place) no longer attached to the assembly. The bottom section of the fastener, and the circlip were found in the rear fuselage, however the spring was not recovered. Yellow paint was observed on the outside surface of the nut, along with some minor scoring damage. The circlip and associated components were examined visually, but no evidence of damage to identify the failure mechanism was observed. The recorder was placed in the rack to assess the location of the fasteners in relation to the hooks. While the pins could be inserted into the rear face of the unit, the FDR - 106 - did not sit flush with the upper plate due to the permanent deformation of the rack. As a result, the right fastener could not be secured over the hook on the front of the FDR in the as-received position. The threaded nut of the left fastener appeared to be further from the hook; however it should be noted that a full examination of the effectiveness could not be performed, as the spring loaded mechanism was not recovered. A.3 Maintenance The documentation provided by the operator indicated that the FDR was installed in A6-ERG on 17 September 2008, following overhaul on 13 September 2008. The overhaul notes stated that the underwater locator beacon battery was replaced at this time. Instructions and procedures for the FDR had only one line referencing the fastening mechanism during installation. The installation instruction stated, “Lift the fasteners and tighten the knurled nuts until the DFDR is correctly attached”. The document had no reference to how tight the nuts should be fastened. A.4 Conclusion The damage observed on the FDR rack was considered to be the result of the tailstrike event. The vertical forces from the impact, acting on the weight of the FDR unit, would have imparted sufficient load to the rack through the fasteners, to permanently deform the aluminium sheet of the upper tray. The upper tray exhibited permanent plastic deformation/buckling along the vertical axis, towards the fastener end, in the order of 14 millimetres. With the upper tray deformed, the nuts would have been able to disconnect from the FDR hooks, leaving the unit unsecured. The deformation was observed to be equal on the left and right sides of the upper tray, which indicated that both fasteners were secured at the time of the occurrence. While a part of the left fastener had been separated from the rack (the spring assembly), the reason for the failure could not be determined. - 107 - APPENDIX B : AIRCRAFT INFORMATION B.1 General Figure B1: A340-541 Source: A340-500 FCOM Vol 1 The aircraft data at the commencement of the flight is listed in the following tabulated format. Manufacturer Airbus Model A340-541 Serial number 608 Registration A6-ERG Year of manufacture 2004 Certificate of registration Issuing authority General Civil Aviation Authority United Arab Emirates Issue date 30 November 2004 Certificate of airworthiness Issuing authority General Civil Aviation Authority United Arab Emirates Issue date 30 November 2004 Period of validity 30 November 2008 to 29 November 2009 Total airframe hours/cycles 22,526/2,598 Last maintenance check 11 March 2009 Next scheduled maintenance due 29 March 2009 Maximum certified take-off weight 372,000 kg Maximum certified landing weight 243,000 kg Maximum certified zero fuel weight 230,000 kg - 109 - B.2 Engines The aircraft was equipped with four Rolls-Royce Trent 553-61 high-bypass turbofan engines. Each engine was certificated at 270 kN (60,000 lb) thrust and 1 de-rated91F to 248 kN (55,780 lb) thrust for operation on the A340-500 series aircraft. B.3 Airworthiness The Aircraft Technical Log entry for the flight indicated that a pre-flight inspection was completed at Melbourne by the ground engineers at 2130 in preparation for the flight to Dubai. The log noted ‘nil defects’ from the previous flight. A label on the overhead panel indicated that the No 2 high frequency (HF) radio transmitter was inoperative. B.4 Weight and balance The following information, from the ACARS loadsheet (Appendix H), was transmitted to the flight crew at 1053:31 UTC: 2 Dry operating weight92F 183,235 kg Zero fuel weight 226,549 kg Take-off fuel 135,300 kg Take-off weight 361,849 kg Fuel burn-off 125,300 kg Landing weight 236,549 kg The above weights were within the approved limits for the aircraft. The ACARS landing weight was for the intended landing at Dubai. The approximate landing weight at Melbourne following the accident was 280,000 kg. 3 Take-off centre of gravity was 27.1% of the mean aerodynamic chord93F , and was within the approved limits for the aircraft. B.5 Overweight landing Although the aircraft landed at a weight in excess of the maximum landing weight of 243,000 kg, the operator reported that an overweight inspection was not required in accordance with the Aircraft Maintenance Manual, as the vertical loads during the landing were less than 0.6 g. 1 De-rating an engine restricts the thrust output to a level below the potential maximum for the engine design. 2 The dry operating weight is the total weight of an aircraft for a specific type of operation, excluding the usable fuel and traffic load (cargo, passengers and bags). 3 Mean aerodynamic chord. The chord of an imaginary wing of constant section that has the same force vectors under all conditions as those of the actual wing. The centre of gravity location is normally referenced relative to the mean aerodynamic chord. - 110 - B.6 High lift devices The aircraft was equipped with leading edge slats (slats) and trailing edge flaps (flaps) to increase the lift from the wings. The aircraft also drooped the ailerons (lowered their trailing edge) when the flaps were lowered to further increase the lift while maintaining lateral control (Figure B2).

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