CF Fork: painted?
 

My Pilot 1.2 has a Bontrager HCM CF fork. Don't know much past that. Last couple of rides I've had a noise on the bike. When riding over cracked/rough pavement. Sounds like a fingernail tapping on the fork (that hollow high pitched sound, sound more like tapping on the fork than if I tap on the Al frame). I noticed the headset was slightly loose so I tightened it (didn't seem loose), did another ride and the noise was worse, so I don't think it's the headset.

Digging deeper I noticed a chip of paint coming off the dropout. Is that normal? I didn't think it was painted, but I guess it is. I don't see a crack, but I plan to look more closely tonight.

Carbon is almost always painted with at least a clear coat, mostly for UV protection I think. The clear coat cracking/chipping can give you a heads up about cracks or damage, causes many false alarms as well though.

Check silly things like QR skewers tight? Specifically with some Trek bikes I've seen a loose derailleur hanger combined with a loose skewer cause all sorts of weird noise.

Don't be afraid to take it to a Trek dealer or at least email some pictures to Trek. Visible damage or not assuming everything is tight and shouldn't be causing noise it's worth checking out.

You know, I did think the front skewer was a bit more loose than usual. I'll tighten that and see if the noise goes away. That'd be an easy fix! Thanks.