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Fault Tolerant Aileron Actuation System for Regional Aircraft

Periodic Reporting for period 2 - TAIRA (Fault Tolerant Aileron Actuation System for Regional Aircraft)

Reporting period: 2018-10-01 to 2020-03-31

The primary flight surfaces of aircraft are currently actuated mainly by Hydraulic Actuators (HA) when Electro-Hydrostatic Actuators (EHA) are used as a backup (e.g. Airbus A380 and Gulfstream G650). Electro-Mechanical actuators (EMA) are used mainly for actuating secondary flight surfaces (e.g. Boeing B787). To reduce the weight and power consumption of actuation systems, the more electric actuation is becoming demanded. The latest programs and activities (e.g. Smart Wing by SAGEM, More Electric Initiative or All Electrical Wing by CASA) are heading to a wing without hydraulic pipes supplying actuators that means using EMA/EHA instead of HA. The electric actuators are further step on the path from Fly-By-Wire (FBW) to Power-By-Wire (PBW) system where the central hydraulic supply and several hydraulic circuits are not needed at all.

This project is linked to the work plan of Regional Aircraft IADP within Clean Sky 2, specifically to the topics under the Work Package 2.4 Innovative Flight Control System. The project results will enable reliable electro-mechanical aileron actuation, the last step needed to dispose of the aircraft hydraulic system. This will significantly reduce the aircraft weight (and therefore specific fuel consumption), and in addition it will reduce energy reserves inherently needed in each power system (again leading to lower specific fuel consumption). Elimination of the hydraulic system has many advantages:
- Reduced maintenance costs
- No hydraulic oil (no need of replacement and disposal)
- Increases modularity of the aircraft, enabling wider component sourcing
- No risk of oil leakage, with positive environmental and airport safety implications

The overall project objective is to develop an aileron actuation subsystem for regional aircraft consisting of two Electro-Mechanical Actuators, planned for active-active operation of single aileron, and two dedicated Electronic Actuator Control Units (EACU), and to demonstrate its maturity. The subsystem is being designed to achieve the following high-level objectives:
1. Compact & Lightweight EMA Design
2. Safe Actuation System
3. Easy & Cost Effective Maintenance
The TAIRA project was launched in April 2017. The project plan is divided into 6 logical development phases:
1. Requirements definition
2. Preliminary design definition
3. Critical design definition
4. Actuation units manufacturing
5. Actuation units testing and delivery to the TM
6. Customer support for integration and V&V on the Iron Bird simulator

In the requirements definition phase, the project team defined the most appropriate actuation subsystem architecture based on long term experience in the development and production of both, the Electro-Mechanical Actuator (EMA) and the Fly-By-Wire (FBW) Flight Control Systems (FCS). Detailed actuation subsystem architecture trade studies were performed focusing on many aspects of the future FCS to maximize the foreseen benefits of EMA based actuation. The subsystem architecture trade studies dealt with the challenges, whether genuine to the EMA, such as safety risks associated with mechanical jam, or specific to regional aircraft application, especially the space restrictions for integration into wing structure.

The preliminary design phase started in October 2017. During this phase, Honeywell significantly progressed with the actuation system design. The preliminary design phase was successfully accomplished after several review meetings with the Topic Manager (TM) in July 2018.

After the Preliminary Design Review (PDR) milestone was achieved in July 2018, the technical team started working on a detailed design of the Actuation Unit (AU)System. The scope of this development phase included:
- Development of the detailed design of the AU.
- Development of safety analysis.
- Development of Prognostic Health Monitoring algorithms.
- Development of control laws.
- Development of system model and its validation via simulations.
- Development, manufacturing and assembly of an AU mock-up.
- Testing of the AU mock-up.
- Development of the detailed design of the dedicated Test Bench

AU’s detailed design included development of hundreds of mechanical and electronic components drawings and conducting multiple technical analyses (Thermal analysis, Modal analysis, Response analysis, etc.). The manufacturing of the final AUs will be very costly and the requirements defined by the TM are very challenging. Therefore, to de-risk potential future non-compliance of the final AUs with the requirements, the project team decided to develop, manufacture, assemble and test the AU prototype. The AU prototype was not fully representative; however, the team could have validated the performance of the detailed design and thus significantly reduced the related technical, schedule and cost risks. Another meaningful effort was invested in development of the Test bench detailed design. The Test Bench design development included development of a) Hardware part, b) Software part and c) Mechanical part. Also, the detailed Test Bench design was subject of the CDR with the TM.

The detailed design phase was successfully accomplished by the Critical Design Review with the TM in August 2019. After this significant project milestone, the team started with manufacturing of 4pcs of the AUs. 3 of 4 AUs will be delivered to the TM for a further testing on the dedicated Iron Bird simulator, 1 AU will be used for environmental testing in Honeywell. On the end of the 2nd reporting period, all MC components were delivered to Honeywell and team progressed with their debugging. Also the majority of EMA components were already delivered.
The core ambition of the TAIRA project is to significantly improve the state-of-the-art of certifiable EMA subsystem for primary flight surface actuation system. This item is aligned with current global trends of aircraft electrification (More Electric Aircraft). On the project end, the EMA technology will be integrated and validated on the regional aircraft iron bird simulator. It will be a significant milestone on the path to deployment of Power-By-Wire system on regional aircraft.

The TAIRA project brings to the market improved Actuation system performance with lower maintenance cost. The following main impacts to the European aircraft manufacturers are expected:
- 150kg weight saving. This expected weight saving on aircraft level can be transferred into less fuel burn or additional passengers.
- 4% fuel saving. A hydraulic actuator is a continuous load on the engine whether hydraulic power is used for actuation or not. An EM actuator however can be configured using a “power on demand” strategy. Consequently, this reduces fuel consumption at engine level.
- 4% reduced aircraft emissions. Due to the obtained weight and energy savings, the TAIRA EMAs will help the aircraft to reduce fuel burn, and thus environmental pollution. This is a significant impact that helps the industry meet the ACARE SRIA and Flightpath 2050 goals.
- Reduced pollution and waste. The elimination of hydraulic fluids helps removing the environmental impact of wasted fluids (due to leakages during operation, or spills during maintenance works). The reduced need for spare parts (due to higher MTBF and Condition Based Maintenance) helps reducing overproduction and consequential waste material (waste material from production, and spare parts stock that never is used).
EMA design presented on the PDR