The trucks gives an empty array when I use configFile >> "cfgVehicles" >> "truck name" >> "HitPoints".
In the config browser in the editor there is two parents named HitPoints.
I guess the one is the actual, while the other is empty.
By bad luck it will choose the empty HitPoints config instead of the real one.
Edit: Some of the helicopters don't give the HitPoints as well. {F20689} {F20690} {F20691}