Aerodynamic measurement probe

An aerodynamic measurement probe to measure a local angle of attack of an air stream flowing along an aircraft fuselage, said probe comprising:

• a support and a shaft, said shaft being able to rotate about a longitudinal axis with respect to the support, the support and the shaft being configured to form between them a gap, said gap passing around an annular tab of an end of the shaft in the support, maintaining a functional clearance allowing said end of the shaft to pivot freely in the support, and said gap communicating, through an annular groove with drain holes of an impurity discharge circuit, the gap comprising an inner annular groove about the longitudinal axis, the inner groove being made in the support, and the inner groove opening out away from the axis directly onto an end part of the annular tab,
• wherein the gap further comprises said outer annular groove, about the longitudinal axis, made in the support, and opening out toward the axis, so that the annular tab is positioned directly between the inner and outer grooves;
• the outer groove, the tab, the inner groove and a chicane downstream the inner groove protecting mechanical rotation elements of the probe from impurities, impurities being drained through the drain holes away from said mechanical rotation elements to be discharged by gravity.