Don't know any downloads you can make, but I can say that I've had the same problem with many downloaded planes (not EuroHarmony ones, though).
I've always assumed it was a graphical error made by the plane makers, or the game just hasn't detected the gear. But then again, I don't really know much about making the planes in FS so I can't say for sure!
Hope you find a download or a solution soon, Javier!