We still had a 'bend box' at the Warminster 34 Command workshops when it effectively closed in 2012 or so - and nobody knew what it was. Mind you, most of the stuff was even beyond an old Armourer like me! I think it could be tested in any plane as it's the steel that is tested. The box had degree marks on a frame marker so you could accurately test it. Most unusual 'thing' was a big roll of the binding wire for No1 EY rifles and new fore-end strengthening bolts