I think that's the big problem. I'm using the OpenCollada exporter 2014 trying to export from Max 2015 and its just leaving the mtl file blank, so I need to fill it in manually, and keep filling in the wrong names for the materials (Hence the metallic 787 above). Any word if their will be support for more textures soon and possibly for Max 2015?
Here you have OpenCollada exporter for 3ds Max 2015:
DownloadI'm using it to export World2XPlane model library, and it works perfectly
As for your problem with weird looking textures, try to only have albedo textures without roughness, normal or any other types, written in .mtl file. If after that it looks fine, I think that the problem is caused by normal and/or roughness textures. If that's the problem, then I would recommend you to take a look at the default Cessna for example, and see how those textures looks like, and compare with yours.