on the boeing yc-14, the upper-surface-blowing design for high aerodynamic lift used two jet engines that blew high-velocity airstreams over the inboard section of the wing and over special trailing-edge flaps. the large multisection flaps extended rearward and downward from the wing's trailing edge to increase the wing area, thus creating extra lift, which was further augmented by positioning the engines so their jet blast across the upper wing surfaces created still more lift. in addition, the placement of the engines above the wing prevented the engines from ingesting dirt and debris and shielded some of the engine noise from the ground so that the transport could make a quieter approach.