Method to Determine Internal Leakage of Aircraft’s Hydraulic Servo

Abstract

This paper addresses a method to determine possible internal hydraulic leak of airplane control servo. Internal hydraulic leakage is difficult to perceive due the leak doesn’t have any visible evidence outside the control servo. Leaking happens past the hydraulic piston or through faulty control valves. Such leaking can have serious consequences due servo’s decreased capacity and force especially situations where all the aerodynamic force of control surface is needed to maintain the ability to control the airplane. This kind of hidden failure can advance unobserved because decreased capacity of the servo can be enough to keep the airplane in control during normal flight conditions. However, in heavy flight manoeuvres such as aerobatics, the decreased rate of control surface’s angular velocity can lead to in-flight loss of control. One relevant problem is how to find out when inner leakage is so severe, that it endangers safety of the airplane. To solve this kind of problem, a detailed quantitative model has been built. This model utilizes recorded in-flight process data and aircraft’s aerodynamical characteristics to determine condition of the control servo.