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VALidation tests of ElectroMechanical Actuators and its dedicated control units at TRL 6 level

Periodic Reporting for period 4 - VALEMA (VALidation tests of ElectroMechanical Actuators and its dedicated control units at TRL 6 level)

Reporting period: 2019-11-01 to 2021-04-30

Nowadays, there is a trend towards the More-Electric Aircraft (MEA) concept. MEA would replace the individually optimized but collectively sub-optimized secondary aircraft power systems (electric, hydraulic and pneumatic) with a globally optimized electrical system. However, the architecture of the electric system must be carefully selected to optimize the whole aircraft.

Current research in MEA technology is focused on new advances in power electronics, fault-tolerant electric machines, digital control, electro-mechanical actuators, fault-tolerant electrical power systems and communications. Modern technologies involved in MEA are being taken in two different paths:
• Elimination of bleed-air systems and hydraulic engines with further improvements in electrical power generation capability. It requires changes in both electrical generation and distribution network.
• Replacement of hydraulics actuators with electro-mechanical actuators with the same level of safety and reliability, reducing weight, fuel usage, maintenance and production costs.

The interest in the replacement of the traditional electro-hydrostatic actuators used in flight control surfaces by electro-mechanical actuators is based on the following reasons:
• Weight and maintenance reduction.
• Elimination of pipes vibration problems.
• Increase of reliability due to fewer hydraulic elements.
• Increase of the system performance due to the decrease of the number of components and pressure losses thanks to the absence of valves.

With this approach the VALEMA Project follows two main objectives.
On the one hand manufacture and assemble units (EMAs and ECUs) previously designed and developed in EMA4FLIGHT according to the JTI-CS2-2016-CFP03-SYS-02-14 Call (Development of electromechanical actuators and electronic control units for flight control systems) for in flight tests activities.
On the other hand to perform certification activities regarding both the HW and SW of the ECUs in order to obtain a permit to fly in the FTB2 demonstrator of the Regional Aircraft.
The manufacturing part will include a deep analysis of manufacturing routes, materials to be used and applicable qualification tests, searching for innovative processes, in order to ensure that the processes optimize the manufacturing time, minimize the raw material used and minimize the environmental impact.
The certification activities will be aimed at obtaining the Permit to Fly from the Airworthiness Authorities for the aileron/spoiler ECU hardware and software, according to DO-254 and DO-178C, respectively.
These activities can be considered as the last step within the HW and SW design of the aileron/spoiler ECU development undertaken in EMA4FLIGHT and, as such, the innovations developed within that call also apply herein.

Additional information provided by the Consortium member in their websites:

Other publications:
1. CLEAN SKY 2, GMV helps to reduce the environmental impact of aeronautical technology, pgs. 14, 15
2. The VALEMA project kicks off, another stride forward in the development of operational critical software, pgs. 16, 17
3. GMV consolidates its aeronautics certification and development skills, pg. 18
4. Tecnalia develops Electronic Control Units for the electrification of aeronautical systems,
Work performed until the end of this RP is summarizes herein:
- Manufacturing: The plans and requirements have taken into account the system requirements and the manufacturing routes have been analysed in order to optimize the manufacturing time, the raw material used and the environmental impact. The motor, ballscrews and Flap-Tab ECU have been manufactured and most of them have been delivered.
- HW certification: The PHAC generated within the EMA4FLIGHT project has been reviewed and updated and the records required for the certification is being collected. The PHAC has been formally approved by the Certification Liaison.
The development plans for the aileron/spoiler ECU HW generated within EMA4FLIGHT have been reviewed and updated.
The test benches for the acceptance tests have been adapted.
- SW certification: the development plans and standards generated within the EMA4FLIGHT project have been reviewed and updated. These plans and standards have been formally approved by the Certification Liaison.
The documentation and evidences for software requirements and preliminary design have also been generated and approved by the Certification Liaison. These elements have been updated and internally approved for the critical design review.
Additionally, several tasks for testing and formal verification of the source code have been performed.
The following potential innovation aspects are expected to be achieved during the development of the EMA4FLIGHT and VALEMA projects:
• Manufacturing: Innovative processes, routes and materials will be thoroughly analysed in order to ensure that the processes optimize the manufacturing time, minimize the raw material used and minimize the environmental impact.
• Permit to fly: The certification activities, when obtaining the permit to fly, will ensure that the systems developed within the EMA4FLIGHT project reach a TRL 6, enabling the potential innovations already described within EMA4FLIGHT in terms of:
o EMA Control algorithm: The proposed control algorithms to be developed within the precedent EMA4FLIGHT project, assures maximum performance of the mechanical system and low degradation due to incorrect operation point of the EMA.
o Power electronics and ECU: Power electronic based in SiC components will be thoroughly considered for the ECU development. This solution offers the higher power/weight ratio and low heat dissipation, extending thus the life time of the ECU. In case of using common electronic devices (IGBTs), the power module will be carefully calculated avoiding any oversizing assuring thus the most reduced size of the ECU.
• EMA anti-jamming: Achieving an as high as possible level of safety is one of the main requirements of the project. A contingency mechanism for the extreme case of EMA jamming is being taken into account. This anti-jamming system unblocks the jammed EMA allowing free movement. In case of several EMAs acting over the same surface control, this system allows disconnecting the jammed EMA and keeping control over the surface in a degraded mode.
• ECU Safety: Combination of Health Monitoring and Built-In Test in the ECU software, adopting fault tolerant strategies and developing a CON/MON architecture in the ECU with redundant software and hardware, assures the highest safety operation of the system. Besides to prevent jamming condition, in the worst case, or single failure detection, the combination of these strategies allows performing maintenance tasks in the adequate moment, reducing thus maintenance costs, and allows obtaining and storing big amounts of information during EMA operation that allows performing future studies regarding safety and maintenance strategy of the EMA.
Scope of VALEMA project