Well I wouldn't say that this works with the normals flipped. It does show the normal map and I do get an aluminum look but I don't have any texture showing up. Yesterday evening I spent about 8 hours going over the cowl model with a fine tooth comb. I separated the model into different objects so that any surface that over lapped the the main model were in separate objects and could be UV mapped as individual objects. I also checked that absolutely every normal was pointing in a consistent way and in the correct direction and that there were no overlapping surfaces. Still get a black cowl if the normals are in the correct direction.
I tried with out a reflection map and with no cube map. Same results.
But I did discover something. If I disable the reflection effect totally I do get the texture although it is very washed out. The same texture when effects are turned off will render much darker than with the effects enabled. After more experimenting I discovered the turning turning down the strength of the reflection (IE. using a lower value for <reflection-correction>) allowed for the texture to come through.
I have other effects setup for different parts so of the aircraft that are using a different texture. I have not setup a normal map for these parts yet but reflection is enabled and there are both a reflection map and a cube map. I played around with the texture for these parts by drawing wide black lines across the parts and it worked just like I would expect (IE. the black lines show up in sim). Also I have an effect for doing a normal map only for the tire tread on the main gear with no reflection - this works great and I end up with a very nice diamond pattern tread. And another to so the polished stainless steal exhaust covers. I had to flip the normals on the exhaust covers however.
Currently only the cowl, fuselage, tires and wing fairings have a normal map with any features (IE. the others are completely flat). Here is an image of what this currently looks like.
I think I can live with this at least in the short run. But I would really like to understand what is going on with needing to flip normals on some objects. In addition I have a few spots that have Z fighting issues that need to be fixed and turning on effects seems to make that more of an issue.