Abstract: The equivalence between natural aging and in-service aging was created in theory of fatigue strength degradation in this paper. It was done in terms of fatigue life curves for YB-3 Perspex aged for 1,2,3 years respectively in Hainan and aged for 5 years in Anshan district of Shenyang. The accelerated equivalence was provided correctly and precisely with the data of YB-2 Perspex aged naturally in Hainan and serving in flight in the south district.

Key words: the tr anspar ent material fo r aircr aft enclosur e, fatigue st reng th r eduction factor, at mospher icag ing