Over the winter I fitted a new set of wiper blades from a well know source, we were out for a run recently when the rain started so switched on the wipers as it really started to chuck down we stopped under a tree and I jumped out to put the hood up with the wipers still running, unfortunately the blade on the drivers side fell off and by the time SWMBO could reach over and switch them off the arm had scratched the screen.
On examination of the blade and comparing it with an old one it was obvious that the four lugs were not bent over and I hadn’t realised they should be. If fitting new blades make sure the lugs are bent over to prevent the spring lever being loose and the blade working free.