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FP7

FLIGHT-EMA (E-RUDDER) Report Summary

Project ID: 323318
Funded under: FP7-JTI
Country: Spain

Final Report Summary - FLIGHT-EMA (E-RUDDER) (Advanced Flight control system – Design Development and Manufacturing of an Electro Mechanical Actuator with associated Electronic Control Unit and Dedicated test Bench)

Executive Summary:
The FLIGHT-EMA project objectives were the design, development, manufacturing, tuning and validation of an innovative and smart Electro-Mechanical Flight Control system primary Actuator focused towards the study and validation of a future oil less Power by Wire aircraft. FLIGHT-EMA actuator has been based on a modular and efficient approach that has integrated easily exchangeable electric and mechanical components with sensors and control strategies that allow automatic and autonomous safety control. The FLIGHT-EMA Electro-Mechanical Actuator has included its dedicated Electronic Control Unit, a Built In Test equipment to detect potential failures and a disable device to guarantee compatibility with emergency actuation. Different configurations have been studied and evaluated to determine the optimum system architecture from a technical point of view. Volume, mass, electrical consumption, power to mass ratio, reliability, durability and safety are concepts that have driven the development.

The FLIGHT-EMA system has been tested and validated at several stages: Virtual validation at model level and finally actual experimental validations of the complete system through both on-ground and in-flight test campaigns. These sequential and complementary validations assured thus a reliable, safe and efficient performance of the prototype and have provided data for a deep concept evaluation. For this validation purpose, the FLIGHT-EMA project also included the design, manufacture and tune of two test rigs: the On-Ground Test Bench and In-Flight Test Bench. FLIGHT-EMA Test Rig has allowed installation both in Copper Bird® and in the ATR prototype aircraft (Avions de Transport Regional) passenger cabin. The On-Ground test bench also included its own control system and counter-load actuator with its hydraulic and electric power supply systems.

Project Context and Objectives:
In today's aircraft, a small proportion of the power generated by the engines is, on one hand, mechanically diverted (via the gearbox) to electrical generators, central hydraulic pumps and other subsystems. On the other hand, engine high pressure bleed air is used to pneumatically power the air-conditioning system, anti-ice system, etc. The use of electrical Power On Demand systems in place of hydraulic systems are becoming the norm in all new aircrafts developments. The continuing need to reduce overall fuel burn on the aircraft leads to the use of more electrically powered systems. With this approach the FLIGHT-EMA project objectives includes the design, manufacture and tune of an innovative and smart Electro-Mechanical Actuator for the study and validation of a future more electrical flight controls actuation system. FLIGHT-EMA actuator is based on a modular and efficient approach that integrate easily exchangeable electric and mechanical components with sensors and control strategies for an automatic and autonomous safety control.

The FLIGHT-EMA Electro-Mechanical Actuator includes its dedicated Electronic Control Unit, a Built In Test equipment to detect potential failures and a disable device to guarantee compatibility with damping and emergency actuation.

Different configurations have been studied and evaluated to determine the optimum system architecture from a technical point of view. Volume, mass, electrical consumption, power to mass ratio, reliability, durability and safety are concepts that drove the development.

The implementation of the electro mechanical actuator on the aircraft poses different technical challenges that were carefully addressed in order to achieve a competitive solution. The objectives of the project were the following:

▪ To design, develop and manufacture an EMA and its ECU suitable for a FCS Primary actuation application.

▪ To design develop and manufacture a Test Bench (suitable to integrate and test the EMA and ECU) with associated counter load and inertial load simulation systems.

▪ To comply with the high demanding dynamic characteristics: frequency responses, velocity characteristics and dynamic stiffness. The very severe conditions are due to high frequency/short stroke operation. The novelty is to introduce a reliable sizing method for ballscrews applied in applications new for EMA’s use, as well as a control laws that manage the system.

▪ To perform a dedicated testing activity in order to verify and validate the EMA/ECU and test bench performance.

▪ To achieve the large required force values at the primary flight control surfaces, the ATR rudder in this case: The implementation of the EMA in the Primary Flight Control System is a challenge from mechanical integration perspective due to the limited space envelope available that affects directly to size and weight of the EMA.

▪ To ensure the mechanical integrity of components: usually flight control primary actuation equipment are subjected to a harsh vibration environment, with significant mechanical shocks. The effect of the unsprung mass requires a careful assessment of all the elements involved as well as the connection to the vehicle structure. The mechanical integrity is of particular importance to connectors and sensors implemented on the motor.

▪ To ensure thermal stability: The thermal transients must be analyzed in detail to ensure a robust and durable condition within the design envelope.

▪ To ensure a safe operation even in the case of failure: it has to be ensured that the failure in the electromechanical actuator or power electronics does not compromise the emergency operation.

▪ To ensure that the EMA meets the previous objectives with maximum power to weight ratio.

The FLIGHT-EMA system has been tested and validated at several stages: Virtual validation at model level and finally actual experimental validations of the complete system through both on-ground and in-flight test campaigns. These sequential and complementary validations assure thus a reliable, safe and efficient performance of the prototype and provide data for a deep concept evaluation.

This innovative concept of FLIGHT-EMA actuation system, fully electrically powered, is the result of a multidisciplinary approach that has considered modularity, compactness, assembly easiness, user friendliness, process autonomy and safety in an integral way, assuring a positive environmental impact, with an increase in the quality and reliability of the flight control actuation system.

Project Results:
A trade-off study was carried out between a direct drive and a gear drive architecture and considering the requirement to minimize the actuator space envelope and the overall weight. The earliest EMA mechanical architecture contemplated significant improvements from previous R&D developments, incorporating an optimized ball-screw (and almost backlash-free), a 270 VDC motor, duplex LVDT and an innovative anti-jamming system.
Key characteristics that were identified: space envelope, maximum weight, load-stroke curves and finally, reliability and safety requirements.
Regarding Test Bench, Work Package 1 was aimed to the understanding and clarification of the project specifications. Final main specifications and capabilities of the Test Bench are:
• Two different test benches have to be developed
o On-ground test bench: for the Copper Bird facilities test
o In-flight test bench: for the ATR in-flight tests

• On-ground Test bench main capabilities:
o Maximum static load: 45kN
o Maximum dynamic load: 30kN
o Maximum speed: 140mm/s
o Dimensions: 2570x700x1620 mm
• In-flight Test Bench main capabilities:
o Maximum load: 30kN
o Dimensions: 1959x654x562 mm
Work continued on work package “WP2-Conceptual Design” and the EMA preliminary design was presented in the PDR meeting. Performances general overview, interfaces, thermal aspects, safety issues, basic components were also presented.
The Electronic Control Unit module architecture was also included, as well as ECU hardware preliminary design, ECU functionality, control algorithm and ECU MTBF and Safety issues. The complete ECU system is made up of three main components: ECU main box, Damping resistor and Crowbar resistor. The ECU box contains three electronic PCBs: Power module, AJS and ECU main board.
Each board is mounted on a printed circuit and is connected through a set of electrical signals. The Anti-jamming System has also a control module and a power module, but both are mounted on a single printed circuit board.
The design included a connector for wiring at the eye-end part (control surface side) that was not accepted by TM . New designs were proposed.. CESA studied and analyzed three different architectures for the final solution: parallel LVDT outside the EMA, parallel spiral cable outside the EMA with cover and a third option with internal wiring.
TM preferred the last option but it was the most challenging solution.
In-flight test bench: The FLI-TB is totally autonomous except for an electrical power source for the EMA and the limit switches. The EMA is tested using a spring to apply the counterload.

On-ground test bench: the EMA is tested using a hydraulic cylinder to apply the counterload. The GR-TB is totally autonomous except for an electrical power source. It is supported over anti-vibration mounts and has ringbolts so that it can be transported with a crane. The electric cabinet and the hydraulic power unit are placed next to the GR-TB in separate structures.

“WP3-Detail Design” followed conceptual design activities and most of this work was carried out until the end of the reporting period. The final EMA detailed design was presented during the CDR meeting.
Anti-jamming design, wiring routing and a challenging weight requirement were the most important drivers of the development. All detail design activities were performed and documented: design reports, Engineering coordination memos, reliability and safety analysis, detailed performance characteristics, stress analysis summary, interface control documentation, final compliance matrix and final drawings.
Some activities of the ECU detailed design were also performed:
• ECU block diagram
• Power module and anti jamming system
• Mechanical and electrical interfaces definition
• ECU functionality definition
• ECU control algorithm
• Position control loop strategy and simulations

Once the schematic design was considered closed, the work continued with PCB design of the three boards, that is, anti-jamming board, ECU power board and ECU control board. This task includes footprint definition, routing style definition, component placement and track routing.
During this period, the Anti-jamming board was manufactured, mounted and tested (see picture below). During test execution, some mistakes in design were corrected.

ECU power board and control board manufacturing also started. These first board prototypes will be used to perform hardware-firmware integration and to validate the design. After this integration, some minor changes in the design are expected.
Finally, in parallel with PCB design and manufacturing, a deeper safety analysis was performed so as to guarantee that safety requirements are met in this first issue of the design. This safety analysis includes besides MTBF, a FMEA analysis, a FMES and a quantitative safety requirement analysis.
In-flight and On-Ground test bench detailed design has been performed.
WP4 included validation plan and detailed test procedures, as much as possible in accordance with airworthiness standards that were specified in TM applicable documentation. Performances, temperature, vibration and electric tests were included.

WP5 Manufacturing, Integration and Tuning: Integration and assembly of this challenging equipment was considered critical and with a high level of difficulty. For this reason it leads to the issue of a detailed and meticulous assembly process, which also includes the design of necessary tooling.
WP6: Validation and Qualification Tests
Validation and Qualification tests include two levels of validation: On-Ground validation testing, and in-flight campaign qualification approach. Minimum validation for On-Ground campaign delivery include EMA mechanical performances, ECU control performances, power input and other standard electrical tests. Qualification tests for In-flight campaign delivery also includes vibration, operational shocks, EMI/EMC, magnetic effect, electrostatic discharge, etc.
Two units of actuators were assembled to face validation campaign in the shortest time in order to recover some delay. EMA unit started to perform validating tests. They included:
• ENDURANCE TEST CURVES
• FUNCTIONALITY TEST
• Performances: different loads, speed and position commands
• Control parameters for several load curves
• Fail Safe Mode
• Anti-jamming system
From this starting point, EMA and ECU started On-Ground validation process, a hard and intensively work was carried out until the actuator was sent to ATR facilities. Initial validation consisted on functionality and performances tests needed for on-ground validation. The most challenging activities regarding control, was to improve the control parameters to achieve the maximum operating load, 30KN in both directions, tensile and compressive, and to perform the operational requirements related to maximum operating bandwidth.
EMA and ECU demonstrators continued with mechanical and electronic set-up activities with the IFTB in order to prioritize validation for flight demonstration. Activities lasted until In-Flight delivery in March 2016. As a summary qualification tests for Safety of Flight included
• Acceptance Test (functional and performances)
• Vibration tests and Operational Shocks
• Voltage Spikes as per section 17 RTCA DO-160F
• Emission RF Energy Test as per section 21 RTCA DO-160F
• Magnetic Effect as per section 15 RTCA DO-160F
And other complementary tests
• Power input
• Induced Signal susceptibility
• Audio Frecuency Conducted susceptibility
• ESD as per section 25 RTCA DO-160F"
• Dielectric Strenght
• Regenerated Power
• Running Current
• Starting Current (inrush Current)

As a result of the tests, some modifications have been done along the test campaign. It included, among others:
• modifications of mechanical ANCRA fixation because of vibration tests conclusions, and other ECU fixation
• flame retardant special wiring manufacturing and integration
• addition of new filters for the conducted emissions, modifications of wiring and connectors included addition of new resistors for 270Vdc inrush current, modifications of wiring and connectors included
First integration of the Flight-EMA system unit on ATR flight demonstrator took place. Activities and on-site support at ATR demonstrator took place.
On-Ground Test Bench and EMA were finally delivered for on-ground validation to Copper-Bird facilities (Labinal Power Systems in Paris). The consortium tested and integrated them just after delivery, and also gave on-site support at Copper-Bird facilities when Labinal Power System performed integration tests.

Along the period the consortium worked also in simulation model activities, in close collaboration with the TM and updating the models according to different requests. Three model configurations have been compiled to SaberRD® for the last delivery.

Potential Impact:
Employment in Aerospace and Defence industries reached 794,695 in 2014, which represents an overall increase of 14.2% in comparison with 2009. Aeronautics itself reach 534,621 employees and 33% dedicated to Research and Development activity , including a significant number of SME’s. Concerning the market forecasts for this sector, Airbus has conducted a Global Market Forecast to 2035 that anticipates that air traffic will grow at 4.5 per cent annually, requiring some 33,000 new passenger and dedicated freighter aircraft at a value of US$ 5.2 trillion over the next 20 years. That Global Market Forecast also states that that order book value will be driven by producing eco-efficient aircrafts, which will involve producing highly efficient aircrafts, engines, actuators and feed-drives. Therefore, it will be crucial for the Companies involved in the Aeronautical Value Chain to conduct reliable and efficient validation tests on the new developments for those eco-efficient aircrafts, and the cornerstone for that efficiency will lie in having safe, and reliable technological prototypes and validation tests for those aircraft components.

The More-electric and All-Electric Aircraft concept is a major target for the next generation of aircrafts to lower consumption of non-propulsive power reducing fuel burn. With this aim, several collaborative research and development projects have been related to the development of systems for the future All-Electric Aircraft. They have shown the main aspects of the improvements obtained when electric systems are used instead of hydraulic ones: energy saving, maintenance operations reduction, leakage-related problems absence and health monitoring system compatibility among others.

In this global scenario, the FLIGHT-EMA concept for the main landing gear actuation systems for a full scale aircraft will have a remarkable impact on the Competitiveness Position and Sustainable Development of the European Aeronautic Industry, because these FLIGHT-EMA system will contribute to:

▪ Increase the competitiveness of the European aeronautical industry by developing new and advanced technologies.
▪ Meeting societal needs for environmentally friendly and safe validation processes
▪ Developing and TRL increase of more efficient, compact and reliable systems
▪ Contribution to reach EMA cost targets fixed by airframers by means of standardization and off-the-shelf components integration.
▪ Improve fuel consumption management.
▪ Compliance with European and World initiatives towards sustainable mobility and societal changes

European Commission Flightpath 2050 includes the goal (among others) of mitigating the environmental impact of aviation effects. In 2050 technologies and procedures available will allow a 75% reduction in CO2 emissions per passenger kilometer to support the ATAG target (Carbon-neutral growth starting 2020 and a 50% overall CO2 emission reduction by 2050) and a 90% reduction in NOx emissions. The perceived noise emission of flying aircraft is reduced by 65%. This highly ambitious goal can only be achieved by a combination of several measures. One of them being the improvement of jet engines together with aerodynamic design and innovation in “energy architecture” of aircraft.

FLIGHT-EMA contributes to and strengthens the leading role of the EU to combat climate change. Ultimately, this will generate jobs and growth. And it is fully in line with the objectives of the CLEANSKY JTI.

New technologies may open the door to high performance, environment friendly and economic aircraft operation by better exploiting available weight reduction potentials of new design philosophies without compromising the existing, high aerospace safety requirements. These technologies are also enabling even improve safety of aircraft operation by means of more affordable and efficient integrated sensing / actuating technologies.

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Related information

Contact

Eva Novillo, (R&D Manager)
Tel.: +34 916240138
E-mail
Record Number: 192740 / Last updated on: 2016-12-14
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