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Content archived on 2024-04-19

Electrically Powered Integrated Control (SMART) Actuators


It was the intention of the Pilot Phase programme to demonstrate the feasibility of producing high integrity Electrically Powered Actuators (EPA) for Primary Flight Controls applications. This objective has been fulfilled both for the Electromechanic Actuator (EMA) and the Electrohydrostatic Actuator (EHA).

It is the main objective for the follow-on programme (EPICA) the further development of the concepts and hardware resulting from the Pilot Phase specially in the following areas:

Continuing investigation of even more compact electric motors, using the very latest magnetic materials, for possible introduction in EHA and EMA's for Fly/by/wire Flight Control Actuation.
Integration of the power electronics module within the actuator.
Evaluation of different solutions for heat dissipation.
The validation of Pilot Phase predictions for electrically powered actuation simulation models.
The analysis of more deep test results and the comparison of the performances of both EMA and EHA for Flight Control System application.
Prepare a model specification for Flight Control Actuators.
Methodology development for electrically powered actuators design and analysis.
Correlation between analysis, simulation and test result was successfully demonstrated and thus enhances the methodology development for electric actuation, a major objective of the programme.
Conclusions from the work undertaken up to now show that as a result of the studies and extensive laboratory testing it can be declared with some certainty that an aircraft fully digital fly-by-wire flight control system is now within realization. Both EHA and EMA have shown the capability to fulfil most of the specification requirements without any major modification. Some non-conceptual, but major, modifications will be required to meet a few specification requirements in both EHA and EMA solutions. The EMA actuator seems to have slight better efficiency that the EHA actuator, though EHA efficiency has been substantially improved during the EPICA programme by reducing the internal leakage of the pump. Nevertheless the data presented in the programme still indicates that the EMA solution is about 5-10% more efficient than the EHA.

On the other had the EMA actuator has shown extreme difficulties in meeting the dynamic requirements when two actuators are used to drive a flight control surface in active-standby configuration. This problem related to the size of the electric motor is aggravated as power requirements increases with the size of the aircraft. Therefore it is anticipated that EMA technology will better fit the smaller aircraft is considered.

As a result of the failure analysis it is felt that EMA actuators will need to incorporate a jamming avoidance system in order to maintain fail-operative characteristics after a single jamming.
Low and high temperature testing has been conducted on both types of actuators. In the range of temperatures requested by the specification no problems or deterioration of performances has been observed for the EMA actuator. Low temperature testing in the EHA has shown that performance requirements cannot be met below -30 C of fluid temperature. Therefore the EHA actuator has to incorporate means to maintain operating fluid temperature, both in active and standby mode, higher than the above mentioned limit. Both FCA and EPICA programmes have been centered on actuators sized for typical commercial transport aircraft in the range of 150-200 passengers. These studies cover or can be extrapolated to a range of aircraft up to 300 passengers. Above that size, flight control system actuation power requirements grow so rapidly that even the feasibility of such electric actuators may be in question. Certainly a new actuator architecture will be required, as well as to overcome new problems related with the huge power that these actuators will have to handle (up to 10 or 20 times that of the EPICA actuator).


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S/N,Avenida John Lennon S/N
28906 GETAFE

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Participants (14)