FURTHER STUDIES ON THE ATMOSPHERIC CORROSION RATES OF AN AIRCRAFT STRUCTURAL ALUMINIUM ALLOY - CONTROLLING FACTORS AND MECHANISMS

摘要

Because military aircraft spend most of their life on the ground, it is a reasonable assumption that corrosion in aircraft structure occurs predominantly while an aircraft is on the flight line or in maintenance. The corrosion, which typically occurs in joints and fastener holes in aircraft components, is the result of the atmospheric environments, which develop at military aircraft bases. These environments are the result of various climatic factors, which include rainfall, humidity, airborne salt contamination, and dew point temperatures. DSTO has commenced a study to determine how the rates of propagation of corrosion in high strength aluminium alloys are related to these varying atmospheric factors. This information will be used to assist in setting corrosion inspection intervals. This paper discusses the effects of these climatic variables on corrosion propagation and the influence of sheltering of the type provided by flight line carport shelters and maintenance hangars. It considers in detail the differences in corrosion rates occurring on plain surfaces of these alloys and those occurring inside joints and fastener holes in specimens designed to replicate typical components of aircraft structure made from these alloys.