One-step co-curing process of manufacturing the composites cover panel with stiffeners for wing fuel tank by applying open expansive silicon rubber die is presented. In view of more serious defects existing in the parts of initial manufacturing stage

including warp

stiffeners size out-of-tolerance

delamination and dense voids

the corresponding design modification

process improvements and quality control measures

are introduced. Perfect parts are obtained eventually

and the function check and flight tests with these parts are passed.