In-flight upset - 154 km west of Learmonth, WA, 7 October 2008,

Electrical flight control system commandsAs discussed above, the FDR showed coincident movement of both elevators, andthat the response of the elevators was consistent with flight crew inputs, prior to andafter (but not during) each pitch-down. In addition, the FDR showed that theautopilot was not connected during the two pitch-downs, and was therefore notproviding inputs to the EFCS at that time.EFCS pitch commands were not recorded on the FDR. However, the FDR showedthat there were recorded spikes in AOA 1 data at the time of the two pitch-downs.As discussed in section 1.6.5, the EFCS could initiate a pitch-down command if itdetected that the aircraft’s AOA was too high. The EFCS algorithm for determiningthe AOA value to use when computing flight control commands is based on thethree ADIRUs’ inputs (section 2.1.5).1.12 Aircraft and component examinations1.12.1 General aircraft inspectionVisual inspection of the aircraft at Learmonth found significant damage to overheadfittings in the passenger cabin (section 4.3). No other aircraft damage wasidentified. There were no missing or loose fasteners, no creases or folds in thefuselage skin, and no signs of damage or distress to any of the fuselage, wing orempennage skin, fairing panels or flight controls.The FDR data showed that the peak vertical accelerations during the flight were-0.80 g and +1.56 g, with almost no lateral acceleration. The aircraft maintenancemanual defined the normal flight operating range as -1.0 g to +2.5 g. Aircraftoperation within this range did not require additional inspections. Based on a reviewof the FDR data, the aircraft manufacturer asked for a visual inspection of theelevator servo-control attachment fittings. This inspection found no problems.After removal of the cargo, the aircraft hold’s structure and restraint systems wereinspected for damage which might be attributed to the event. No problems werefound.1.12.2 Post-flight reportTypes of messagesThe post-flight report (PFR) was produced by the CMS at the end of each flight.The PFR contained fault information received by the CMS from other aircraftsystems’ BITE and the FWS.PFR messages were of two main types:• Cockpit effect messages. These level 3, 2 and 1 ‘failure level’ messages weregenerated by the FWS and presented to the flight crew on the ECAM and/orother displays (section 1.6.9). The messages enabled the flight crew to knowwhich operational functions were no longer available.• Maintenance fault messages. These class 1 and class 2 ‘failure’ messages weregenerated by the CMS, based on inputs from other systems (section 1.6.10).- 45 -