Apparatuses and methods for attaching jet engines and other external structures to aircraft wings are disclosed herein. In one embodiment, an aircraft system includes a wing and a unitary fitting fixedly attached to the wing. The unitary fitting can include a first portion having at least a first attach feature and a second portion having at least a second attach feature. The aircraft system can further include an engine or other external structure positioned proximate to the wing and coupled to the unitary fitting. The unitary fitting can be configured to transfer at least approximately all of the flight loads from the external structure to the wing.