By now, a large majority of you would have seen the video of the Embraer EMB-202A agricultural aircraft that experienced an inflight structural failure of both wings in Brazil. Thankfully, the pilot survived with reportedly only a broken collarbone.
From a distance, this looks like an effect of Va decreasing with a decrease in weight. The design maneuvering speed (Va) is the speed at which the airplane will stall before exceeding its design limit-load factor in turbulent conditions or when the flight controls are suddenly and fully deflected in flight. Under these conditions the airframe experiences an increase in "G-force" or "load factor."
The limit-load factor of certificated airplanes is based on the maximum amount of G-force the airframe can withstand before becoming damaged. Airplanes stressed up to but not beyond their limit-load factor should experience no structural damage. (This assumes the airplane is like new and not previously over stressed.)
To ease in the explanation of why Va reduced with a reduction in weight, we have included a video from Boldmethod explaining it in short but informative detail. Check it out below.