BrianG

Alan, Came across your post and had not seen it earlier. I am the distributor for Oratex fabric for Australia and New Zealand. You can find me at : http://www.wheelerswings.com.au/ Happy to assist as required. Regards Brian

I hesitate to respond to your question since there are a number of things to check. In addition I have to state that I am the Oratex representative in Australia and NZ so feel free to be sceptical. Clearly you need to make absolutely sure that there is no structural damage and that you are only looking at a repair to the old fabric covering. It also will depend on where the hole is and where the patch edges will be. Having said that, Oratex has been and is used in repairs to other types of fabric coverings. The chaps in Alaska get a lot of stone damage and so they have had to address this problem. You may wish to see the video clip on the North American Oratex agent's site copied below: Using Oratex to repair Ceconite. If you go down this path, I would urge you to first make sure that you test the bond strength of the Oratex material and it's adhesive to your particular aircraft's (unknown) covering, using a small test piece. There are simple and low cost ways of doing this to quantify the strength and so give yourself confidence, in advance of actually doing it, that the bond can be as good if not better than the existing bond of fabric to structure. I can guide you through that. The Oratex adhesive bonds really well if used correctly and ideally that requires some pressure onto the outer surface while triggering the adhesive at the correct temperature. Imagine it as pressing the adhesive into all the tiny pores in the two surfaces while at temperature in order to get best bond strength. In your case you are probably trying to bond to an unsupported surface (unless you can get a hand in there). So in your case you have to do what you can to still ensure that you can apply pressure. I recently supplied some adhesive to patch a Cub in SA and if you contact me off line I can see if the customer is happy to be contacted by you for an independent bit of advice. I would put strength and safety before looking pretty. Oratex comes with UV and in a choice of colours but the colour match and the finish almost certainly will not be identical. Oratex do offer a paint so you can still paint over the top if required. You may want to play it safe, put a wide enough strip symmetrically on each wing in a striking colour and long enough to place any leading edge in a safe downwind position. Make a feature of it. The additional weight can be calculated in advance and since Oratex is light, the weight addition will not be much. If you want to get hold of me to discuss this in more detail, you can reach me via the website: Wheelers Wings - Home Brian

Gents, I have some comments on leak testing in this thread that may be helpful. I recently needed to leak test two wing tanks and the main tank for a Dakota Hawk I am building. I first used balloons filled with air (a safe low pressure test) and looked for bubbles. Aircraft grade Balloons and bubble liquid were bought from the local party shop. I found one very small leak. The chaps in the club were a bit sceptical about this test so I went back to the party shop for some helium filled balloons. ($1 each) I fortunately have access to a helium sniffer gun. This is a very sensitive method. The Helium molecule is small and if there is a path is will escape. It will pick up your breath if you don't brush your teeth. By this method I quickly found a second leak. On redoing the bubble liquid on the second leak, and knowing where is was, I could just see it. My conclusion is this. You can miss small leaks by immersion in a water bath (the supplier did). An air pressure test with bubble liquid is good but you have to go over every joint very slowly and carefully in order to see a small leak. Helium and a sniffer if you have access to it is the best. It also is a way of sometimes testing in position as the instrument probe has a long nose for sniffing and a small vacuum pump. The instruments voice gets squeaky (beeps) if it finds a leak in the vacinity. I made the mistake of not washing the bubble liquid off and it dried and it has marked the aluminium so there must be some chemical in there. I suggest you wash off with water immediately afterwards.

Hi Geoff. It is easy to practice first. You just need some fabric and a small amount of the adhesive and you can see what the final result will look like. It is not a difficult or messy process. One chap covered his entire aircraft inside his house next to the lounge room. Few of us could get away with that. There are some technical tips on the website under technical Info. I am not sure if the example of covering the rudder is what you looked at. It is under technical at: Wheelers Wings - Home Cheers

Hello Lou, I should have added that ORATEX have a policy of not having distributors keeping stock other than samples. The reason is two fold. They want to keep a record of every aircraft and link it to each batch of material as part of their quality control. ORATEX fabric does not have a shelf life so you can purchase it and use it when required. The second reason is that the thermal setting ORATEX adhesive does have a shelf life and you should only order it when you are ready to cover. ORATEX want to be sure customers are shipped fresh adhesive. The adhesive bond is very strong, but regardless there is a simple test for bond strength as part of your quality control.The adhesive is water based so shipping is not an issue. Not handing volatiles is one of the advantages. You would probably be aware that no filling, painting or UV coating is required. Best contact me and I can address any more questions.

I have samples of ORATEX materials and have been for ORATEX factory in Germany for training. I was so impressed with this product that I offered to represent ORATEX locally . I now am the Australian and NZ distributor. You can look up wheelerswings.com.au for more info. Contact me and I will do what I can to help. Regards Brian

Hello John. I note you have plans for a FFP Dakota Hawk. These don't seem so common in Australia. It is on my shortlist for a home build project. Did you proceed with yours? Are there any others in Australia?