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

The first simulation tool, OCAS 103 , used a real-time computer to link the controllaws with an aircraft movement simulation. It accepted inputs from simplifiedcontrols including a sidestick controller, and the results were displayed on asimplified primary flight display. Design engineers used the tool to assess thequality of the control laws and their effects.Another simulation tool, OSIME 104 , simulated the complete flight control system,including the computers, actuators and sensors. It linked the SAO definition of thewhole system to the complete servo-control modes and to the simulation of aircraftmovement. There were several hundred inputs into the system, includingparameters such as weight, centre of gravity, wind and turbulence, and ADIRUinputs such as altitude and airspeed. This tool allowed the engineers to inject valuesof the parameters and examine their effects.In addition to helping validate the design prior to building the software andassociated equipment, the simulation tools allowed design changes to be efficientlydeveloped and evaluated. They also enabled ‘non-regression testing’ 105 to beconducted early in the change process to help ensure that any proposed changeswould not introduce new problems.Testing and simulations (after building the equipment)After the EFCS hardware and software was built, it was subjected to a series offurther verification and validation activities, including:• Test of the equipment on test benches. The flight control computers were testedby providing simulated inputs and observing the internal parameters. Testbenches were also used to tune the servo-controls for each control surface.• Tests on the ‘iron bird’ and flight simulator. The iron bird was a test platformwith systems installed and powered as on an actual aircraft, and the flightsimulator incorporated an aircraft flight deck and flight control computers. Forsome tests, the iron bird and the flight simulator were coupled.• Flight tests. Several aircraft were fitted with comprehensive flight testinstrumentation, recording more than 10,000 flight control parameters for lateranalysis.The manufacturer conducted the tests and simulations according to specified testprograms. If the behaviour of the system was not satisfactory, a problem report wasraised, registered and investigated. If any of the testing identified a need to modifythe system design, the resulting modification was again subject to safetyassessment, simulations, testing and other verification and validation activities, inaddition to non-regression testing to ensure that no new problems were introducedas a result of the change. The design was not ‘frozen’ until all of the designevaluation activities were completed.103104105Outil de conception assistée de spécification.Outil de simulation multi-équipement.Non-regression testing (also known as regression testing) determines whether any changes madeto a system have led to any problems with the existing system functionality.- 92 -