HAP 2: Detection of Contamination

Failure to detect sensor icing or ice accretion on aerodynamic effective surfaces is a major cause of icing accidents. An enhanced situational awareness of the pilots for potential aircraft degradation aids to avoid critical flight situations.

Detection of ice contamination is necessary to prevent an aircraft system failure, if sensor readings become unreliable. Furthermore, hazardous flight situations based on erroneous sensor readings must be avoided, e.g. the angle of attack limitation is exceeded and goes undetected. Investigation of different topics is necessary for the detection of icing, the determination of the limited aircraft capabilities, and for the prevention of system failures. The current research concerns the following questions:

  1. Is it possible to detect ice accretion on a single sensor in redundant systems, and how to reconstruct a missing signal from the available ones? For the detection of sensor errors in systems containing two identical sensors additional measurements have to be taken into account. Operating with combined air data and inertial reference systems requires measurement of different aerodynamic parameters. Losing these measurements due to sensor failure leads to significant system limitations.

  1. Are there alternative sensor concepts to reliably measure air data in icing conditions? Ice accretion has only a minor influence on telemetry systems, like optical sensors, placed inside an aircraft.

  1. Is it possible to conclude ice accretion from aircraft behavior? Using common System-Identification methods parameters of an aircraft model can be estimated from flight data. The research goal is to reliably determine the parameters of an aerodynamics model in-flight, further to reason icing from the estimation results, if there is an accretion, and calculate the degraded aircraft capabilities.

  1. How could the pilot’s situational awareness be enhanced by suitable indications?

The main goal of the research is the reliable detection of aircraft icing based on different systems.

The first steps in the main work package are the concept development for the data flow of relevant weather information, which should be displayed. Moreover an online parameter estimation tool is developed for the ice detection system, and a first version of the tool was tested during a flight test campaign with the DLR research aircraft ATRA.

 

Dataflow concept for weather information
 
DLR research aircraft ATRA and experiment work stations