Hi Nick, Two years ago I had the same problem, what I did after find the exact position from the outside of the wing, I finally did;
Open a few control plates so you can put your hand in it, and feel on the main spare where a nut is fixed on that spare. With a small point to push from the inside of the wing trough the outside, then you know where to put your Tie down. Hartmut give me once the exact dimensions, that is also a very good start where approx the nuts are. Hope this will help you, my English is not good but I try to explain what I did. Greetings from Belgium, Robert Robert Rombouts Ercoupe 415D - Sernr.4577- 1947-OO-PUS - www.ercoupe-be.net [email protected] http://ercoupe.multiply.com/photos
