The spinner should be affixed to the fan by the person assembling the plane, so that it becomes hard to remove.

I've seen a few N.P. planes come with the spinner cones CA'd in, but this makes it impossible to remove the fan assembly... and of course people have complained about this practice

Your best bet is to ALWAYS use a microdot of CA at two places on the spinner to affix it only after you have properly balanced, broken in and otherwise check out the EDF. You only need the tip of a toothpick's worth of CA, no more. You may need to break the CA seal later!

This applies ot most EDF's of similiar design.

There are other albeit far more expensive EDF assemblies that go about all of this differently, but most low cost EDF motors use this same scheme.

e.g. it's identical to the T.H. Hyperflow, etc.

So ALWAYS make sure that you pre-flight your EDF properly.

These planes should always be gone over by someone with EDF experience before flying them.