Aircraft joints and corrosion control

Abstract

Corrosion damage in aircraft structure, if undetected and/or left untreated, can undermine safety. Currently corrosion prevention and management in many civil and military fleets still relies strongly on the use of traditional 'find and fix' maintenance practices, although this has been refined by the increasing use of Corrosion Prevention and Control Plans (CPCP) which provide a framework for targeted inspections and treatment to help with corrosion management. Teardowns of high-life service aircraft and parts can also be valuable tools to help identify corrosion-prone areas and relative severity of the corrosion. This paper describes research which supports the development of improved prognostic capability for corrosion, by investigating one particular factor which appears to play a significant role in the development of corrosion. The focus of this research is to better understand and predict the deterioration and breakdown of protective paint coatings at aircraft joints, primarily due to the influence of mechanical displacement. The impact of in-service mechanical loading on coating degradation has so far received little attention, despite clear evidence that coating tend to fail first at specific site such as sheet ends and fastener heads. Potential service/performance implications of the joint displacement on the protection of ageing aircraft are discussed. More importantly, it is argued that appropriate corrective actions are required immediately after the paint cracking detected, even if active corrosion is not fully evident.