By removing the blue light from the heli there is no longer an error on server restarts. No errors for 2 days now

That seems to be sufficient evidence that the code related to the blue light was the cause. How important is that feature to you? I probably won't get to fixing it anytime soon since I have lots of other work to do.

I'm still wondering, what is special about your map or server that would cause you to experience the issue. Are you using a custom map? If procedural, can you share the size and seed?

it's just a procedural 4500 all seeds as long as I can remember, no the blue light isn't the be all n end all, I've already disabled it in the config. must be that time of day thing you suspected. thanks for your time sir will mark as resolved