An AOG on a Cessna 680 Citation Sovereign. Threaded inserts in the magnesium accessory gearbox housing of the right-hand engine had been renewed once already and had failed again in service.

Repeating the same repair would only have bought the same short life, so the housing was opened out and a thicker-walled insert fitted — an insert repair of an insert. The heavier wall gives the thread more material to hold in a casing that is soft to begin with.

The work was carried out on the aircraft, with the drive apertures masked while the pads were prepared and the new inserts set.