A fellow builder from the Netherlands recommended this Sikaflex 295 UV adhesive to me. He uses it to fix acrylic windows in the yachts the company he is working for is building. What is good for such top yachts must also be perfect for my airplane.
Indeed this is perfect adhesive for the windshield. I used this under the retainer and at the sides and the top of the windshield. Easy to work with. The big advantage compared to butyl based products is that the surface of Sikaflex can be painted afterwards.