"Design, development and manufacturing of an electro-mechanical actuator and test rig for AiRcrafts Main LandIng Gear acTuation systems."

Final Report Summary - ARMLIGHT (Design, development and manufacturing of an electro-mechanical actuator and test rig for AiRcrafts Main LandIng Gear acTuation systems.)

Executive Summary:
TThe ARMLIGhT project objectives are the design, manufacture, tune and validation of an innovative and smart Electro-Mechanical Actuator (EMA) for the study and validation of a future complete all-electric landing gear actuation system. ARMLIGhT actuator is based on a modular and efficient approach that have integrated easily exchangeable electric and mechanical components with sensors and control strategies allowing automatic and autonomous safety control. The ARMLIGhT 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 emergency actuation. Different configurations were 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 were concepts that drove the development.

The ARMLIGhT system have 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 were intended to assure reliable, safe and efficient performance of the prototype providing data for a deep concept evaluation. For this validation purpose, the ARMLIGhT project also includes the design, manufacture and tune of two test rigs: the On-Ground Test Bench and In-Flight Test Bench. ARMLIGhT Test Rig allow installation both in Copper Bird® and in the ATR prototype aircraft (Avions de Transport Regional) passenger cabin. The On-Ground test bench also includes its own control system and counter-load actuator with its hydraulic and electric power supply systems

Project Context and Objectives:
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.

In an attempt to reduce weight and cost -by diminishing fuel consumption-, improve environmental impact –reducing use of hydraulic fluids and lowering fuel burn particles-, and to some extent increase safety and reliability, A/C designs are leaning towards the “All Electric Aircraft (AEA)” concept. Although, this concept may seem feasible nowadays, AEA major challenges need to be overcome:

· Safety and reliability: prove electrical systems maturity and assure the operation in the event of any possible failure.
· Mass and Volume optimization: miniaturizing devices such as IC, gears or motors.
· Harsh environment including:
- Thermal constraints: as there is no fluid which could be used as a natural refrigerator, need to evacuate heat through other methods arise.
- High Vibrations.
- EMI / EMC: adequate electrical protections are necessary to protect electronic circuits.

The benefits of the electric A/C are clear and some applications are being already targeted with the introduction of electric motors as a replacement to hydraulic ones or even the removal of a complete hydraulic system. Such achievement has recently been accomplished in A380 and A350 aircrafts with 2 electric 2 hydraulic circuits architecture (2H2E).

The absence of hydraulics also greatly reduces costs and simplifies maintenance activities. Diminution of operating costs will be patent in the forthcoming years as these A/Cs operate on a regular basis. The objective in a midterm is to eliminate another hydraulic circuit (1H2E) using the remaining one for landing gear and some primary flight control actuation until the AEA is achieved in a long-term horizon.

Regarding Landing Gears, there are multiple actuators required for stowing, deployment and steering during take-off, landing & taxiing to and from the runway. Actuators have been mostly hydraulic and much of the More Electric Aircraft research involves investigating electrical alternatives.

A good sample of the existing sizes, pressures, strokes and load capacities used on different aircrafts are (All actuation systems presented here has been designed, developed, manufactured and certified by CESA):
· Main Landing Gear Retraction actuation of Eurofighter, Airbus 350 and Airbus A400M;
· Nose Landing Gear Retraction Actuation of AIRBUS A330-340, AIRBUS A340-500/600, AIBUS A380 and A400M;
· CLG retraction actuator of A-340

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

- To achieve the large required force at the main landing gear: The implementation of the EMA in the MLG 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 the main landing gears components 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 electro-mechanical actuator or power electronics does not compromise the emergency extension operation.

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

The ARMLIGhT system was 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.

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 ARMLIGhT project objectives includes the design, manufacture and tune of an innovative and smart Electro-Mechanical Actuator for the study and validation of a future complete all-electric landing gear actuation system. ARMLIGhT actuator is based on a modular and efficient approach that integrate easily exchangeable electric and mechanical components with sensors and control strategies that will allow automatic and autonomous safety control.

The ARMLIGhT 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 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 drive the development.

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

- To achieve the large required force at the main landing gear: The implementation of the EMA in the MLG 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 vehicle main landing gears are subjected to a harsh vibration environment, with significant mechanical shocks. The effect of the unstrung 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 are analysed 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 extension operation.

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

The ARMLIGhT system will be 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 ARMLIGhT actuation system, fully electrically powered, is the result of a multidisciplinary approach that will consider 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 main landing gear actuation systems.

Project Results:
At the very beginning of the project the entire consortium held a Kick-off Meeting. From the first Consortium and Topic Manager meeting, both companies CESA and Tecnalia worked on the first understanding and analyzing all the preliminary requirements from the Call for Proposal. It leaded to the most basic Actuator and Test Bench architectures, presented and discussed during the meeting. The earliest EMA mechanical architecture contemplated significant improvements from previous R&D developments and background, incorporating a simple ball-screw, a 270 VDC motor, backlash-free gearing and an innovative anti-jamming system.

Image 1. First analysis of EMA architecture

Key characteristics that were identified: extended and retracted length, space envelope, maximum weight, load-stroke curves and finally, reliability and safety requirements.
After receiving the first formal specifications from Topic Manager, the consortium started to work on new and more detailed requirements, all applicable and reference documentation as well as on the EMA / Test Bench performance characteristic, issuing a Compliance Matrix (EMA Specs and Requirement Analysis). Because of those requirements, the EMA architecture changed and improved in order to meet the requirements, some of them very challenging such as weight. All that work was carried out under the framework of the “Work Package 1 Specifications”.
From the Test Bench point of view the Work Package 1 was aimed to the understanding and clarification of the project specifications. Project specifications have been defined in a COMPLIANCE MATRIX document (Test Rig Specs and Requirement Analysis). 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 load: 38kN
o Maximum speed: 45mm/s
o Dimensions: 1000x650x1000 mm
• In-flight Test Bench main capabilities:
o Maximum load: 25kN
o Dimensions: 1000x650x1000 mm
“WP2-Conceptual Design” concluded with the EMA preliminary design that was presented in the PDR meeting. CESA considered different architectures and after a trade-off study, selected the final EMA architecture. CESA proposal was based on a direct drive motor architecture, featuring an inverted ball screw in order to protect the recirculating ball system from external agents as dust, ice or water. It also incorporated an anti-jamming system.
Performances general overview, interfaces, thermal aspects, safety issues, basic components and electronics were also studied.

Image 2. Updated EMA architecture includes Direct Drive motor

Regarding test rig systems, on ground test bench and in-flight test bench preliminary design have also been developed (Test Rig Preliminary Design. PDR)

From electronic control point of view, test bench main controller is composed by a national Instruments CompactRIO and a MOOG PTC. The CompactRIO will offer the versatility of reconfigurable system in order to control several task: communications, synchronization, test configuration, GUI and system monitoring while PTC will be in charge of the load and position control loop of the hydraulic cylinder.
Due to changes in the specifications initial specified dimensions are not fulfilled. No mayor issues with the required space are generated in either ATR or CB.
“WP3-Detail Design” followed conceptual design activities concluding on the final EMA design that was presented during the CDR meeting. Anti-jamming design 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. Tasks regarding ball screw and wiring harness were also accomplished in close collaboration with suppliers. It included final design of interfaces, other technical aspects, supplier tests, technical meetings and teleconferences.

Image 5. EMA 3D model

Integration of the actuator on its Electronic Control Unit, as well as integration on On-Ground test bench, were really challenging activities. At the very beginning just after EMA first assembly, EMA actuator performed basic acceptance tests. CESA manufactured some tooling in order to tests basic functionalities before sending the EMA to Tecnalia including checking of:
• Resolver communication
• LVDT communication and functioning
• Anti-jamming motor
• Main actuator electrical motor
• Mechanical checking against counter load
Soon after, the actuator was sent to Tecnalia facilities where the On-Ground Test Bench were installed, for functionality and performances tests.
After surpassing some mechanical problems in the first months (mechanical frictions, anti-jamming cables and wiring, motor overeating, connectors, resolver synchronization, etc) the EMA unit started to perform validating test.
Regarding ECU unit, a first prototype of the boards was used to perform hardware-firmware integration and preliminary testing in order to validate the design. After this integration, some changes have been introduced in the final design of the three boards. Several versions of different ECU were developed, ending in version four.

During the last period the Consortium focused on validation and qualification tests activities being part of the Work Package 6. After delivery of two actuators, one EMA unit to Copper-Bird facilities and a second unit to the ATR flight demonstrator, CESA and Tecnalia gave all needed on-site support, involving always skilled labor when required.
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.
EMA unit started to perform validating test on ARMLIGhT serial number CE501. It included:
• Endurance test curves (9 seconds imposed time): normal, maximum and limit loads.
• Endurance test curves as per QTP
• Functionality test
• Duty cycles
• Fail safe mode
• Stall load
• Anti-jamming system
From this starting point, EMA and ECU started On-Ground validation process, a hard and intensively work that lasted several month, when the actuator was sent to Copper-Bird facilities. All the validation consisted on functionality and performances tests that was needed for on-ground validation.

Image 12. Tuning of the EMA and ECU units on On-Ground Test Bench at Tecnalia facilities

A Review Meeting was held between the consortium and Topic Manager on Tecnalia Facilities. Picture below shows some demonstration activities during Topic Manager company visit. Specifically, anti-jamming activation.

Image 13. EMA unlocked after anti-jamming system activation against 20 KN load

One EMA unit with the On-Ground Test Bench were finally delivered 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.

Image 14. ARMLIGhT actuator installed on On-Ground Test Bench
being integrated with Copper-Bird at Labinal Power System facilities

Along the period CESA and Tecnalia worked also in simulation model activities, in close collaboration with the TM and updating the models according to different requests. The last simulation model delivery took place after reviewing the parameters with final results. Three model configurations have been compiled to SaberRD® for the last delivery.
After On-Ground delivery the consortium continued working on the tuning and validation for the in-flight demonstrator, by means of a second EMA and ECU unit.
The In-Flight Test Bench was integrated and instrumented for vibration tests.

Image 15.Assembly and integration of In-Flight test bench

The EMA and its ECU also performed vibration tests, mounted on a specific tool according the plan and procedures.

Image 16. EMA and ECU performing vibration test at INTA facilities

EMA, ECU and In-Flight Test Bench demonstrators continued with mechanical and electronic set-up activities. 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

Image 17. Second EMA unit installed in In-Flight Test Bench

First integration of the ARMLIGhT system unit on ATR flight demonstrator took place on December 2015.

Image 18. First integration of the EMA and In-Flight Test Bench on ATR flight demonstrator at ATR Toulouse facilities

Activities and on-site support at ATR demonstrator took place from its first delivery until March 2016.

Image 19. EMA actuators and Test Benches installed on the ATR aircraft for in-flight test campaign

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 ARMLIGhT 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 ARMLIGhT 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.

ARMLIGhT 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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Final Report Summary - ARMLIGHT (Design, development and manufacturing of an electro-mechanical actuator and test rig for AiRcrafts Main LandIng Gear acTuation systems.)

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