So, I've been training Carmen (12ish weeks old) in the aviator harness for about I dunno 3 weeks or so now. At first, she didnt mind it at all, we went outside and she flew around. As the days go by though, shes getting worse and worse. She wont stop chewing. And if I try to touch her, she'll growl and bite (HARD!). I tried taking her outside and distracting her with flying and the few times I got her to stop chewing, Se would start to chew on the thing in mid air, come to the groung and just roll around trying to get it off.

Does this make sence to anyone? She didnt have a problem with it at all a few weeks ago, and we havent missed more than mabe 3 days in the past few weeks. Is it possible that some birds just wont wear a harness no matter how young you start them?

Is she molting? She will not want the harness on if she is! I've stop with the aviator harness at moment for this reason.

Yes, new pin feathers will be iritated if so.
Maybe she doesn't like the color. hehe

I just saw that you said 12 weeks old, so it's not molting. In my experience young amazons 4-5 months old can be a bit weird in their behavior, they seek a lot of comfort yet want to explore and be independent and it confuses them. This is also they age where they start to nip a bit because of that insecurity vs. independent. You might want to try using the harness at a different time, pick a time of the day where she is the calmast and try again. Just take a step backwards, show her the harness yet don't put it on and so forth. So of re acclimate her to it again. Good luck!