Two reasons: first, paint is missing. If nothing else, it needs a coat of paint. If my airframe paint were scratched by renter negligence, it would be repaired and covered by the renter. This is no different.
Second, although I didn't handle the prop personally before it was sent off, I'm told by both the reporter of the issues and the mechanics that the scratches and dents were deep enough to be easily felt and catch edges. The club didn't hesitate to ground the plane as unairworthy almost instantly when they saw it (even though the reporter only marked it as an observation, not a squawk).
Granted, on the flip side, both the reporter and their CFI, along with the next student and CFI, chose to fly the plane before the club had a chance to inspect the observation. The final pilot before inspection, on the next day, shows only 30 minutes on the schedule, which usually means they did a preflight and didn't fly. That's reflected in the fact that there is no charge to that pilot. They may have brought it to the A&P's attention, not sure right now.
There was one student/CFI combo before the reporter. And before that, the previous pilot was...me. I certainly know I didn't hit anything. I don't remember any rock chips and I didn't even go anywhere. Just pattern work. I do not remember seeing that on preflight. I feel like that would have been a huge error had I missed so many scratches and dents; I don't remember any. It'll be interesting to see how this turns out.
