I have seen a gang of them break and fly apart but not all plastic spinners are created equal. I use big plastic spinners on my gassers that don't get started with an electric starter but I use the CB brand that goes on just like aluminum spinners with a heavy aluminum back plate. The ones I see sailing off into the wind in several parts are the ones that come in the ARFs with plastic pins and the three screws holding them on. If I don't use a good spinner I use one of the HH nuts or spinner shaped nuts that were mentioned, they work great and last forever. I did use one of the CB plastics on an engine that got started the first start up of the day with an electric starter and it lasted a very long time, looked pretty ugly with the groove but it worked fine.