https://pastebin.com/tKcJrfAV, here is the crash report.

Does this happen to other content packs as well?
Im suspecting this might be an internal issue or mod conflict, not a pack one...

I was going to post the configs until I tried changing the local config to match the server config which solved the issue. Also important to note that this crash happened on IAV content pack as well, but only on air vehicles for some reason.

Ah, now having your configs not match, that's 100% going to break things. Closing as this isn't a code issue, it's a setup issue.

Did some extra testing and it seems that custom fuels cause this on the Renault ft-17 for whatever reason.

Edit: Seems to apply for the official content pack entirely and not just the renault.

Strange, this shouldn't be happening. Can you post your mtsconfig.json file? And if you're playing on a server, I'll need the one from the server and your client.