Finalist: Fatigue Technology

Location Seattle, Washington, USA

Achievement Unique blind fastening system to simplify attachment of nut plates. Every aircraft contains thousands of blind nut plates to attach access panels, components or join structures. Most of these are fixed using at least three rivets, which not only leads to penalties in terms of time-consuming installation, but also provide a common source of fatigue cracks.

To answer these inherent problems, Fatigue Technology has developed ForceTec, an ingenious blind nut plate system, which in 1996 was used in production of the Lockheed Martin/ Boeing F-22 fighter. ForceTec is based on a cold-expanded split-sleeve technique already used for improving the fatigue life of metal structures. The nut-plate retainer is placed in a single starting hole and expanded into place by pulling a split-sleeve/mandrel through its centre. As the retainer is expanded, stresses are imparted into the surrounding structure, creating a zone of compression which acts like a clamp around the nut plate and effectively shields it from crack-inducing stresses. The system has been shown to increase fatigue life from three to ten times, and takes around one-sixth of the installation time for conventional nut plates. It can be automated and used in composites as well as metal.

Source: Flight International