Aero-engine FADEC Electronic Component Failure Simulation Study

With the increasing demand of domestic and international aviation market for mechanic,the aircraft virtual maintenance training system has gradually become one of the important equipment for mechanic training.As the "heart" of an aircraft,the aircraft engine has been an important part of aircraft maintenance,and the FADEC electronic components are the "brain" of the engine,but in the current virtual maintenance training system,the simulation model for the FADEC electronic components only focuses on the normal function of the system,ignoring the impact of its failure.To address these problems,this thesis establishes a simulation model of FADEC electronic components to support fault injection from the mechanic maintenance training syllabus and maintenance tasks.The main contents of the thesis include.Firstly,with reference to the current airframe maintenance training syllabus issued by CAA and the aircraft type maintenance manual,it is determined that the FADEC electronic components include EIU,ECU,HMU and PMA,and it is clarified that the simulation model should meet the requirements of the maintenance tasks of troubleshooting tasks,testing tasks and disassembly tasks to determine the modeling boundary.On this basis,the overall structure of the simulation model based on the functional model supporting fault injection and the repair behavior model is proposed.Secondly,based on the requirements of maintenance training syllabus and maintenance tasks for FADEC electronic components,the specific functions to be simulated for each electronic component are elaborated,and the functional models of EIU,ECU,HMU and PMA are established respectively by using Sys ML state machine,and the state sets and change sets are divided according to their working processes;the input and output signal sets are divided according to the functions to be simulated.For the characteristics of FADEC electronic components with multiple functional output signals in different states,the functional modules are divided under the states to describe the specific content of the output signals.Based on the FADEC electronic component architecture,the same signals are expressed in the functional modules using the same name variables,and the functional signal connections in different electronic components are elaborated.For the possible disassembly behavior in the maintenance behavior,the disassembly state is defined in the state set,and the disassembly state input signal is defined in the input signal set to describe the state of the electronic component after disassembly.Again,in order to describe the repair behavior of FADEC electronic components in the virtual environment,its repair behavior model is established.Through the analysis of the repair process,it is clear that the repair is actually a process in which the state of the repair object is constantly changing.For this feature,the elements of repair behavior simulation are extracted from the repair process: repair object,repair resources,repair activities,repair scenarios,and repair states,and the repair object is defined as a metamodel.The maintenance activity is defined as the event that makes the metamodel state change,and the constraint relationship between maintenance objects is defined.It is determined that maintenance resources,maintenance scenarios and maintenance object states with constraint relationships are the conditions that need to be satisfied for state transfer,and the maintenance behavior of FADEC electronic components in the virtual maintenance environment is realized by constantly changing the metamodel state.Finally,the proposed simulation model is implemented on the A320 virtual maintenance training system developed in this lab.The functional model and the maintenance behavior model are simulated and validated by selecting maintenance tasks respectively.The final results show that the FADEC electronic component simulation model can meet the maintenance training requirements and the simulation model is practical and feasible.