People call and use their mini copter for a day and then the server restarts so they call another one and the old one wont work. This leaves the old one there and before you know it there are a bunch of them laying around everywhere.

I use minicopter.outsidedecayminutes 55000 to turn off decay for copters so the large scrap heli wont decay. Not sure if this effects the mini copters not decaying leaving them to pile up? I wonder if there is some way I can purge them daily?

Would changing "SpawnHealth": 750.0 to a lower number possibly help with this?

You set the minicopters outside decay to 38 days (55k minutes)...

You're right that the minicopter decay setting affects both scrap helicopters and mini copters.

I'm not aware of an issue where mini state is lost on server load, so I will try to reproduce later today. Are you sure these extra minis are spawned by this plugin, not by bandit vendor or spawned on the road? Can you also confirm you are using the latest version of the plugin?

You can also check out my Vehicle Decay Protection plugin for options to selectively reduce decay for specifically scrap helicopters. You can also explore the option to decay vehicles that havent been used in a while (configurable duration) since that's a good indicator they are basically being wasted anyway.

Yes, I am using the latest version of the plugin. I can confirm these minis are all summond by players using the /mymini command.

I will start using your Vehicle Decay Protection plugin. That will solve some issues for me, thanks!

For the mini heli that stop working, you can sit in them, the blades will start up and then instead of taking off it will stop spinning and is no longer active from then on. Then I can do a /mymini and get another one. The old one will be from before the daily server reboot.

I also confirm this issue happening.
After the server restart, the minicopter entity bound to player is lost and player can spawn new mini without having to use /nomini command first, to get rid of the old one. The mini which existed before the restart, doesn not work either. 

This causes loads of mini entities laying around the map which only increase in number every day, causing extra load on server eventually.

I was not able to reproduce this issue in my testing, but I notice a flaw in the code, which is that the data file is only saved when the plugin unloads gracefully, not on server save or any other periodic interval like many plugins do it. This means that if the server shutdown isn't graceful, all minis spawned since the previous server restart will be forgotten by the tracking, causing the issues you are describing. I can have a fix out later this week, which will save the data more frequently.