The assembly of aircraft structure using fasteners can be very difficult and expensive. Some of the most difficult assembly areas occur in compact structures, such as struts (pylons), or major body and wing joints. These difficult access areas drive up assembly costs and reduce velocity through the production line. Design engineers have traditionally compensated by designing access holes with associated doublers to provide access for assembly. Another option is to over-design the joint by utilizing abnormally large quantities of current market blind bolts to compensate for lack of performance.
To address the problem, a new concept in fasteners, called the One Sided Installation (OSI®) bolt, has been developed in a joint endeavor between Boeing Commercial Airplane Group-Wichita Division and Monogram Aerospace Fasteners of Los Angeles, California. This bolt utilizes new design features to obtain excellent structural joint fatigue performance. The OSI is a revolutionary design culminating four years of effort. This bolt is the first blind bolt capable of equivalent usage with shear rated solid shank bolts in fracture critical structure.
While access for backside inspection is still required, OSI fasteners embody the ability to be installed from one side so that backside access is not necessary to complete bolt installation. These fasteners can be significant cost savers by reducing labor hours for assembly. Additionally, OSI fasteners lend themselves very well to robotic installation.