Certification Process For Self-Wetting Continuous Friction Measuring Equipment Used For Construction And Maintenance Purposes On French Airports

Friction characteristics of runways are regularly measured to detect any change in skid resistance and to decide maintenance needs. Self-wetting continuous friction measuring equipments (CFME) are used for functional (construction and maintenance) measurements. Numerous friction measuring devices exist and are currently used on airports. These devices have different functioning principles: operating modes, water delivery systems, measuring tires types and pressures... It causes friction characteristics of runway to be both surface- and device-dependent. Many attempts have been made to correlate friction measuring devices with each other and good results have been achieved for functional friction measurements. Harmonization of friction measurements makes it possible to define minimum friction levels. Below these friction levels, corrective actions have to be taken to improve runway friction characteristics, and pilots have to be informed of such conditions. To achieve this, France has introduced a regulation to submit CFME to mandatory certification. This paper presents the certification process for self-wetting continuous friction measuring equipments used for functional measurements on French airports. Certification ensures aerodrome operators that CFME performs with reliability and consistency. It also harmonizes friction measurements between different devices and ensures a uniform acceptance of the minimum friction level. The certification process consists in correlation trials between the applicant device and the reference device, owned by the French Civil Aviation Technical Center (STAC). A special test track has been built on the grounds of Institut Français des Sciences et Technologies des Transports, de l'Aménagement et des Réseaux (IFSTTAR ex-LCPC). It has 11 differently textured test plots with surface properties covering a large range of friction levels. The performances of all applicant devices in terms of repeatability and consistency of friction measurements are checked. A device meeting the requirements for certification is then correlated to the STAC reference device and is issued with a certificate valid for two years. All self-wetting continuous friction measuring devices used for construction and maintenance purposes on French airports have to be certified. This process has proved to reduce significantly the variability of CFME friction results and progressively improved the overall consistency of applicant friction measurement devices. Examples of test results are presented and discussed in this paper.