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Flyable Electro-Mechanical Actuator (FLEA) Testbed

The FLEA test stand is a lightweight, self-contained testbed capable of supporting three different actuators: one nominal, one injected with faults, and the third providing dynamic load. The load is switched in-flight from the healthy to the faulty test actuator, thus providing the fault injection capability for the test stand without having to modify the actuator in flight. The three actuators and their coupling mechanism is shown below.

FLEA actuator coupling system

FLEA Actuator Coupling system

The stand is connected to the aircraft data bus and the motion profiles for the test actuators, as well as the load applied to them, are derived from the corresponding real-time values for one of the aircraft’s control surfaces. The compact size of the FLEA allows its placement aboard a wider variety of aircraft. Being a largely self-contained unit, the FLEA only requires interfaces to the aircraft data bus and power. The actuators are instrumented with a comprehensive sensor suite, which includes load cells, accelerometers, thermocouples, rotary encoders, linear potentiometers, as well as, voltage and current sensors. The figure below shows an engineering model of the FLEA.

FLEA test stand engineering model
FLEA test stand engineering model

Before a flight, the sides of the chassis (except for the top) are covered with 3 mm thick aluminum plates. These plates serve as an additional safety measure in case of a crash and to provide EMI protection. The top portion of the stand is protected with a high-strength transparent, which allows the operator to visually observe the test in progress. The FLEA aboard an aircraft with its protective panels mounted is shown below.

FLEA aboard an aircraft with protective panels mounted

FLEA aboard an aircraft with protective panels mounted

For more information on this testbed, please refer to the following publications: Experimental Validation of a Prognostic Health Management System for Electro-Mechanical Actuators, Combining Model-Based and Feature-Driven Diagnosis Approaches – A Case Study on Electromechanical Actuators , and Airborne Electro-Mechanical Actuator Test Stand for Development of Prognostic Health Management Systems.

Actuator Prognostic Experiment (APE) Testbed

Actuator Prognostics Experiment (APE) test stand for Electro-Mechanical Actuators (EMA) was designed and built in collaboration with Impact Technologies. While FLEA allows collecting data in realistic flight environments, APE allows conducting experiments on a realistic size EMA. It can be used in experiments studying diagnostic and prognostic methods for ballscrew jams, spalling, abnormal wear, backlash, motor faults, as well as electrical, sensor, and control electronics anomalies. The flexible design of the test stand accommodates test actuators of various sizes and configurations. Dynamic load for the test actuator is provided by a powerful Moog 886 load EMA that can produce up to 5 metric tons of opposing force. The control system of the stand allows custom load profiles and long-term, endurance testing. Instrumentation includes a load cell, accelerometers, high-precision position sensors, temperature sensors, and current sensors. The data acquisition system allows recording of data samples with frequency of up to 64 kHz. The APE teststand is shown below.

Figure 4: Completed APE Teststand APE Teststand