This S-works Tarmac was brought in with what looked like a scratch by the front mech hanger. The ultrasound really came into its own on this job, reporting quite extensive damage below the surface that wasn't visible to the naked eye.
The working theory is that the front mech took an impact and compressed against the frame. The hard edge of the hanger point-loaded and did all the damage, which then spread quite a distance below the surface.
