This is really a technical counselor story, and although it didn't deal directly with an RV, there are lessons for both TC's and RV builders.
A vendor (really a hobby business) has sold a number of fiberglass header tanks for a popular kit aircraft. Like any header tank it will be full of fuel all the time. The popular powerplant for this design is the Rotax 912, so the fuel (in most cases) will be autogas. Most autogas these days contains some ethanol, and that situation isn't likely to change. The builder had already installed the tank when he became concerned about ethanol and asked his TC.
Here's a personal belief, and I think most TC's will agree. A technical counselor can't possibly know everything. He needs to know how to find accurate information.
We got a product description from the vendor, tracked it back to the seller, and determined it was repackaged Dion 6631 isophthalic polyester from Reichhold. A few phone calls got the right Reichhold engineer on the line. Turns out 6631 is not recommended for ethanol.
There are a few million fiberglass storage tanks in service. Gasoline storage tanks are highly regulated, so of course Reichhold does have resins specific for the application, in this case Dion 490 or 495. Both meet UL1316, the current spec for fuel storage.
I am recommending the builder remove the tank. The decision is his of course. I think he will, as he lost his last airplane to a deteriorating plastic tank a few months back.
Never assume a product is suitable just because somebody sells it and somebody else is flying it.
Second, when in doubt, go directly to the root source. Almost every major concern has an engineer detailed to answer questions and supply product data.
Third, if you have a builder with fiberglass in contact with fuel, convince him to check on the resin formulation. Do it for him if necessary. That's why you volunteered to be a TC.
Fourth, if you can get a product data sheet, look for UL1316 compliance when fuel is a factor. There are resins out there with a long gasoline history, but ethanol changes the picture.
A vendor (really a hobby business) has sold a number of fiberglass header tanks for a popular kit aircraft. Like any header tank it will be full of fuel all the time. The popular powerplant for this design is the Rotax 912, so the fuel (in most cases) will be autogas. Most autogas these days contains some ethanol, and that situation isn't likely to change. The builder had already installed the tank when he became concerned about ethanol and asked his TC.
Here's a personal belief, and I think most TC's will agree. A technical counselor can't possibly know everything. He needs to know how to find accurate information.
We got a product description from the vendor, tracked it back to the seller, and determined it was repackaged Dion 6631 isophthalic polyester from Reichhold. A few phone calls got the right Reichhold engineer on the line. Turns out 6631 is not recommended for ethanol.
There are a few million fiberglass storage tanks in service. Gasoline storage tanks are highly regulated, so of course Reichhold does have resins specific for the application, in this case Dion 490 or 495. Both meet UL1316, the current spec for fuel storage.
I am recommending the builder remove the tank. The decision is his of course. I think he will, as he lost his last airplane to a deteriorating plastic tank a few months back.
Never assume a product is suitable just because somebody sells it and somebody else is flying it.
Second, when in doubt, go directly to the root source. Almost every major concern has an engineer detailed to answer questions and supply product data.
Third, if you have a builder with fiberglass in contact with fuel, convince him to check on the resin formulation. Do it for him if necessary. That's why you volunteered to be a TC.
Fourth, if you can get a product data sheet, look for UL1316 compliance when fuel is a factor. There are resins out there with a long gasoline history, but ethanol changes the picture.
