Approach of calendar life extension for aircraft structures

To extend service life of existing aircrafts approaching the end of their original life at the expiration of calendar life while fatigue life is far from running out due to low operation, a calendar life extension approach was proposed based on evaluating technique for life system of aircraft structures under corrosive condition. Methods of identifying candidates for life extension were discussed. Accumulated damage caused by fatigue and corrosion was analyzed to separate the candidates into different classes. On the basis of fatigue life evaluated in general environment (at room temperature and in laboratory air) and expected calendar repair intervals, the remaining fatigue life that considering the effects of corrosion and continued service years were calculated from loading and repair histories using fatigue life evaluation approach in corrosive environment, from which service life was reliably extended for typical operation. Life extension results along with repair schemes for a wing of a fighter shows effectiveness of the approach.