The closest we can get to detection at the moment is when there is a corresponding action in the action menu, or monitoring the vehicle state.
I imagine this acting like an Analog event, where it fires repeatedly as the vehicles state changes (services dont apply 100% instantly)
relevant commands:
https://community.bistudio.com/wiki/getRepairCargo
https://community.bistudio.com/wiki/getAmmoCargo
https://community.bistudio.com/wiki/getFuelCargo
https://community.bistudio.com/wiki/setFuelCargo
https://community.bistudio.com/wiki/setAmmoCargo
https://community.bistudio.com/wiki/setRepairCargo