Service Life Extension Program for Aircraft Structures

 

Stevan Maksimović

Zoran Vasić

Radoljub Došić

 

Performance of aircraft in general, its systems and airframe materials, can be significantly reduced by environmental conditions in which the aircraft operates during the service life. Material performance of steel and aluminum alloys can be greatly degraded because of the environmental conditions (temperature, humidity, UV radiation, pollutants, etc.), which severely affect the integrity and safety of aircraft structure. Apart from the other severe environmental conditions, the effect of the corrosion on structural integrity is a critical issue for damage tolerance design and analysis and needs to be carefully investigated. The corrosion and corrosion fatigue failure process of an aircraft structure are directly concerned with many factors, such as load, material characteristics, and corrosive environment and so on. Attention in this paper is focused on the application of the Nondestructive Inspection (NDI) methods in the process of extension of service life of aircraft structures. The NDI methods were used as a part of service life extension program for the extension of the operation life of the G-4 Super Galeb aircraft structures that have been in service in air force for more than 25 years. The computation and experimental NDI methods and practice steps that diminish the negative effects of corrosion process were shown in this paper. Special attention in this paper is focused to the use of the NDI methods. These steps enable to extend the service life of aircraft structures beyond its designed service life with the accurate prediction of the further service reliability

 

Key words: aircraft, aircraft structure, fuselage, corrosion, corrosion fatigue, nondestructive inspection (NDI), service life testing, service life assessment.