A method and a system for monitoring a measuring chain arranged to collect over time measures relating to a turbojet engine of an aircraft, the system including a processor configured to build a health indicator of the measuring chain based on counting transitions between successive health words defining a validity score of corresponding successive measures. The method includes drawing together at least a portion of the impurities and measuring the concentration of impurities that were drawn together. Molecular modeling studies reveal that organometallic complexes incorporating such calixarene ligands, when combined with an activator such as MAO, should actively polymerize olefins. In some cases cooperating clamp members engage the extension member and the support member to retain the extension member within the cavity. The first kind of gas is pre-reserved in an intermediate portion of a supply path through which the first kind of gas flows, and is supplied into the reaction chamber with exhaust of the reaction chamber being substantially stopped.