Cross fasteners (except the base outside) pressure test must be torque test, does not allow destruction. Cross slide fastener performance, when P = 14KN time, △ 2 ≤ 0.5mm. Docking fastener tensile properties, when P = 6KN time, △ 2 ≤ 0.2mm. Trachoma area greater than 10 mm of trachoma does not allow more than one, and the total area of ??no more than 40 mm. Cross area of ??accumulated sand sticking fastener not greater than 100 mm. Fastener does not allow cross-oxide surface.