Happened about 2 mins after first loading with the mod to building and getting into it, and an auto-save happened while in the heli with a non-recoverable error. it still let me continue and seems to work fine, though.

450.741 Error ParallelScenarioSaver.cpp:156: Saving scenario failed: The mod HelicopterRevival (0.3.0) caused a non-recoverable error.
Please report this error to the mod author.

Error while running event HelicopterRevival::on_save()
Cannot serialise lua functions

Also, i am seeing the factorio-current.log being spammed with:

891.764 Script @HelicopterRevival/logic/heliBase.lua:927: 249948779555.56
891.781 Script @HelicopterRevival/logic/heliBase.lua:927: 249948759555.56
891.798 Script @HelicopterRevival/logic/heliBase.lua:927: 249948739555.56
891.815 Script @HelicopterRevival/logic/heliBase.lua:927: 249948719555.56
891.820 Script @HelicopterRevival/control.lua:156: control.heliDestroyed
891.833 Script @HelicopterRevival/logic/heliBase.lua:927: 249948699555.56
891.850 Script @HelicopterRevival/logic/heliBase.lua:927: 249948679555.56
891.855 Script @HelicopterRevival/control.lua:156: control.heliDestroyed
891.867 Script @HelicopterRevival/logic/heliBase.lua:927: 249948659555.56
891.885 Script @HelicopterRevival/logic/heliBase.lua:927: 249948639555.56
891.902 Script @HelicopterRevival/logic/heliBase.lua:927: 249948619555.56
891.906 Script @HelicopterRevival/control.lua:156: control.heliDestroyed
891.919 Script @HelicopterRevival/logic/heliBase.lua:927: 249948599555.56
891.936 Script @HelicopterRevival/logic/heliBase.lua:927: 249948472888.89

Weird. Thanks for the report!

Also, saw what that 'spam' is...

log(remainingFuel)

Pretty much just debug points. Looking at the rest...

After some investigation, I that's an internal error... I would really like some more information... Like, is this a multiplayer map? If so, how many players?

SP, on vulcanus. not been to other planets besides starting on nauvis

That could be the issue - Heli wasn't been planned to be used anywhere else but Nauvis...

I can see some posta on the form on wanting that on_save being more verbose, but no reply...