Effect of stator height change on bearing life in aircraft autopilot servos

Abstract

Purpose The purpose of this paper is to make a more precise prediction of the life of servo motors used in aircraft. The variation of the axial load created by the wave washer for bearing, which is one of the factors affecting the bearing life of the electric motors and servo motors used in aircraft, was analyzed. Design/methodology/approach In electric motors and servo motors that body as stator, the height of the stator stack affects the compression amount of the wave washer spring. Working with electric motor and servo manufacturers, production-related variations in stator height were determined by making multiple measurements. The reaction forces resulting from these compression amounts were simulated by mathematical modeling with the finite element method, and also experimentally measured on real parts. Findings Results obtained with finite element method and real experiments were compared. By adding the force differences to the general operating conditions, the effect on the bearing life was theoretically determined. In a servo motor with this type of construction, the difference in stator height created different axial loads on the motor shaft. The difference of these loads affected the motor bearing life. Research limitations/implications The results implicated in terms of flight safety, maintenance operation and resource efficiency. Practical implications The results of this study are effective in determining the maintenance intervals more clearly. This study can be used for the design criteria of aircraft servo motors. These servos, which are especially used to move the flight control surfaces, contribute to flight safety as the life expectancy will be clearer. Social implications This study may be effective in preventing aviation accidents caused by servo motors. It can make maintenance management more efficient. Originality/value This study investigated the effect of aircraft servo motor design inputs on servo motor life, considering the production.