How does skydiving flight cause shock cooling?
Skydiving flights are abusive on engines for a number of reasons, but it's all tied to the fact that these flights are all about getting up to altitude, kicking the jumpers out, and putting the plane back on the ground as fast as possible so you can pick up the next group and do it all again, as many times as possible in a day.



While all skydiving descents aren't as dramatic as the video I linked to its not uncommon for skydiving pilots to make a very rapid descent at or near idle power. This causes a more drastic temperature change in the engine (particularly the cylinders, which are not producing as much heat but still have lots of air blowing through the fins).

In addition to the potential damage from rapid temperature changes the engine is also spending relatively little time at cruise power (it's either at full throttle climbing or near idle descending), and depending on the operation may be shut down between jumps. This is far from the ideal situation where the engine would run at 60-75% power as long as possible.