Engineering bodge in the T tail attachment. Dyn Aero had a set of old horizontal tails to fit onto the new model fin, so bodged a fit. The part should have lasted 2000 hrs and was only 42 hrs when it snapped. AC was at 800' at the time. 5 years of litigation ensued with every court finding 100% for the claimants. On final day when damages were awarded, Dyn Aero declared bankruptcy. It was found that they had spent the previous 4 years breaking the company up and funnelling monies elsewhere. Under French law the state had prior claim on what was left.
Note Dyn Aero had 3 tails snap off, but as those accidents were due to engine failure and stalling, the tail attachments were thought to have failed due to impact damage, whereas in retrospect it would appear that they failed because of this same bodge mod.