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Flight Control Laws and Air Data Monitors

This call for tender addresses the further development methods for the two following subjects: the monitoring and real-time error detection of complex flight control laws (lot 1); and the enhancement of detection and tolerance to air data probe complex failure mechanisms (lot 2).

Lot 1 - Monitoring of Flight Control Laws
The project aims to investigate the introduction of flight control law monitors to detect errors. Potential control law errors should be identified, and their criticality needs to be determined. Multiple monitors to detect such errors should be proposed without taking into account the necessary effort entailed. Main challenges for the use of multiple monitors are:

  • the detection is effective when the detection means are sufficiently independent from the item being monitored;
  • the independent monitoring needs to be designed with thresholds and confirmation times set not so high as to not trigger when not needed, and also not so low as to lead to spurious detections; and
  • it may be difficult from monitoring the aircraft behaviour to determine whether the aircraft response comes from a flight control law error, a normal behaviour in a given phase of the flight, and/or an external perturbation.

Lot 2 - Air Data Enhanced Fault Detection and Diagnosis, and Fault-Tolerant Control
Several recent safety events have highlighted that common mode sources could affect consistently two or more air data parameters and remain undetected by state-of-the-art individual and consistency cross-checks, resulting in the use of erroneous air data parameters (e.g. airspeed, angle of attack) in the flight control laws.

Major efforts have been made in the recent years to characterise the icing and environmental conditions air data probes are subjected to during flight and increase the qualification standards;

However, design or maintenance errors, bird strikes, sand projections, volcanic ashes, etc., are also potential common mode sources, and partial solutions (e.g. efficient in a given flight condition only) have been developed to address those events. The project aims to further develop the understanding of such failure mechanisms, and to develop solutions. This will improve the EASA certification standards, and support the evaluation of new designs proposed by aircraft manufacturers.

For all information and status on the call for tender related to the project, please visit EASA.2021.HVP.28.