The E-36 committee is requested to develop a standard or recommended practice for Control System Fault Accommodation to provide guidance on the fault detection and accommodation strategies and robust validation toward certification to FAA Control System regulation 33.28.
FAA has written an issue paper on this outlining the risks and vulnerabilities in fault detection/ accommodation based on industry/agency experience over many years; and suggested means of compliance in terms of tests, analyses, simulations. The E-36 is requested to factor in the issue paper and build on the guidance content into an SAE document for reference by the industry.
In this endeavor, it is recommended that the SAE standard/ARP consider conventional gas turbine controls as well as emerging architectures such Hybrid and Electric Propulsion Systems.
Rationale: A review of commercial engine fleet operations and ~ 500 FAA Airworthiness Directives from 2004-2019 indicates that, a significant number of the operational events are related to Control System fault accommodations. Control accommodation of Input Signal processing and Output driver faults in control systems often have subtle shortfalls depending on the control architecture and detail hardware/software features, transient effects, statistical variation in electromechanical components, accuracy of embedded engine/propulsion models, installation and environmental effects. Despite good intent and effort, significant operational events and disruptions can occur.