In 100% of cases if VANOS spring want to go off - it will remove cap too.
But I'm not sure that in 100% of cases when caps go off - this will cause spring to go off too.
My friend was driving without cap for a pretty long time, maybe half a year and thousands of mileage, without any issues.
Take a look at those caps from the other side, there's no any clips or anything which can hold it on the VANOS unit, seems like it can be removed by hand with really small force. The point is - fallen off caps are not the reason why spring go off too.
Are you guys sure that such a thin piece of plastic can hold such a strong spring?
If anyone have photos of this spring in expanded state, outside of VANOS unit? I can't imagine how it can be possible to drive car if spring goes out.
