Dangerous roof light - partial solution

what is the spring on the video attached to the side, seems that is not helping as pulling the arm down instead of up so any wind/vibration will not help. should the spring be on the other end of the frame which is attached to the window.  

Don't have it open when its windy, Job done 

We forgot about the design fault when we had a caravan with this type of roof light over the fixed bed. It resulted in a pool of water on the duvet due to a thunderstorm when we were out, luckily the whole thing didn't snap off. Yes it's a bad design, our newer one in the motorhome can be partially locked but I think they are flimsy if bad weather occurs.

We only use our large rooflight on our bailey when we are in,we get add ventilation by using the smaller roof lights that can be "locked"in the first stage of opening,i would think any large rooflight of any type would be "vunerable"in windy conditions

We would not use roof vents to cool caravan. If we are out during a sunny day then would not want the light open to the first position shown as we would want the roof blinds drawn to exclude the sun and the blinds are likely to flap madly in a breeze. Just rely on he built in edge ventilation. When we return on a hot day we would open all normal windows and use blinds on sunnyside

Yes, I am surprised that the roof lights didn't have catches to secure them in the open position like they did on the original ones. However, I noticed that the latest models have gone back to having catches to stop them being blown right open when they are in a partial open position (or rather the ones I checked at our dealer's did have). 

Some years ago we had a Lunar with this same Heki midi roof light.

The second time we used the van we left it slightly open as it was very warm, a little breezy and at that point we had not realised how poorly secured they were.

On our return we found it had been lifted by the wind, had cracked at the hinges and a few bits of the plastic were on the floor by the draw bar.  Having borrowed some steps, bought some plastic sheet and duct tape we repaired it as best we could.

We bought and fitted a replacement plastic dome... £190 at the time.

https://www.leisureshopdirect.com/ventilation/caravan-roof-vent/dometic-heki-rooflights/dometic-midi-heki-rooflight-and-spare-parts/dometic-midi-heki-glazing-panel-replacement-dome

We never ever opened it again. It is a very poor design.

I'm puzzled. There is no spring in the Video. You can see the opening bar for the roof light. If you mean the photos, then there again is no spring, although the nylon chord in the photo where I have wound it, then tied it around the opening bar could look a bit like a spring.

This problem doesn't need a windy day to happen. If the wind direction is right, it can happen in quite gentle conditions. But in any case, weather changes, and an adequate and competent design should be good enough to cope with the wind coming up a bit. If you are going out for a whole day, things can change. Of course, if it is a genuinely windy day, then one would keep the light closed.

I had asked my local caravan stockist if the design had been updated, and they had said no. But you say that you have a newer design that has been modified. Thanks for the tip off. I will have to go and look at some of this year's van and motor home models and see if I see what you report.