A pilot I knew was killed flying his brand new homebuilt a few years ago when one of the wings broke in half during a steep turn on final approach. But he designed and built the plane himself and he screwed up on the design parameters.

In general, if the wings are going to fall off a plane, the pilot must have violently overstressed them. It does happen, but I believe usually the pilot has either flown into a thunderstorm or gotten into a death spiral and then overstressed the airframe trying to pull out.

I don't know what would cause a C130 to lose its wings during a water drop - possibly severe turbulence from the fire?