Players are losing fuel
They put fuel in and it will default to 100 randomly.
This plugin only adds fuel to helicopters OnEntitySpawned, it does not touch already spawned helicopters.
Did those players maybe recall their helicopters from VehicleLicense?
Understood. I'm not running VehicleLicense or any plugin like that. I've checked all the plugins for OnEntitySpawned and only one kinda relates to the heli (ScrapHelicopterFix.cs) but that just clears up gibs and fire. Must be something else I'm running.
So you weren't seeing this happen before installing this plugin? To confirm that it's this plugin causing it, you can change the configured fuel amount to something else like 102 and see if people begin reporting the fuel randomly getting set to that value.

Looking for plugins that hook OnEntitySpawned is unlikely to help as it would have to be actual spawning that would be causing this plugin to update the fuel. This plugin being the cause only makes sense if another plugin is despawning and respawning the heli somehow.

Can you post your full plugin list in case something stands out to someone here?

This has only happened since I added the plugin.

I added the plugin back to the server after changing the config to 102.

One of my modirators confirmed that both the mini and scrap defaulted to 102.

I don't feel comfortable posting my plugin list as it's taken me a long while to develop the server to the point it's at.

I do however know what plugins would spawn in a vehicle or respawn in. And there are none that do that to the helis aside from one where you get a skinned box which will spawn a mini/scrap/sedan etc on placement. And that's it. You just have the vehicle. No fuel in the tank, no recall option. It does have CanPickupVehicle and OnPickupVehicle. And no fuel is given on second placement.

One of my modirators confirmed that both the mini and scrap defaulted to 102.

That sounds like expected behavior. The real test is if players report it randomly getting set to 102.

Reading your original post again:

They put fuel in and it will default to 100 randomly.

Were players saying that it gets set to 100 as they were putting in fuel (i.e., they put in 500 and it immediately says 100), or would it change randomly some time later?

Had a couple players put in 1k-2k+. Log out and come back to 100 multiple times.

So I pulled it. Put it back in place like you asked with the 102 setting and once the mod confirmed I pulled it again.

Maybe a long shot, but is there any chance you downloaded this plugin close to the day of release and are running an older version than 0.0.3? The older version is no longer available, but the patch notes show that 0.0.3 fixed a bug. I also dug up a copy I downloaded of 0.0.2 which indeed is not properly marking the fuel item as dirty after changing its amount, which could possibly result in the behavior you're describing.
i'll open it up and take a peek. BRB.

Merged post

[Info("Air Fuel", "WhiteDragon", "0.0.3")]
I just tested out a few things to see if I could reproduce the issue. I did find that restarting the server apparently calls the OnEntitySpawned hook for minicopters (guessing that's the case for all entities) so that reset all of mine to 100. Any chance server restarts are happening before people notice this issue?

The approach of using OnEntitySpawned is also problematic since it affects helis spawned other ways. I've submitted a patch that should only update the fuel of a heli when it is spawned at the Air Wolf vendor (as advertised by the plugin description, but was very much not the case previously). This also fixes the issue where the fuel amount is reduced on server restart.
I'm guessing the server restarted befre the players got back on and saw the change. I have 2 restarts each day around 12:30.