This is why we require that a Flex-a-lite spacer is used with our fans.
5 Fan spacer and bolts;Aluminum contruction;Large bearing surface to a soft radius, to reduce point-loading;California Residents: WARNING Flex-a-lite fan spacers have a large bearing surface and are machined to a soft radius.. 0.This reduces point-loading, which is the most common cause of stress cracking on the fan center star.