There are many reasons why combat aircraft are exposed to high loads. These can result in structural cracks. Heavily stressed parts must therefore be regularly replaced, such as the upper cockpit longeron (UCL) on the F5. 

The complete cockpit has to be removed to replace this load-bearing element. The replacement UCL is an in-house product from RUAG AG. Kaelin conducted this special repair work together with specialists from RUAG AG.