I noticed some popping rivet paint and wondered if it could be because of the exhaust pipe heat but ruled that out and believe it is from flexing the firewall at the inner lower engine mounts. those rivets are working and flexing enough to crack the paint from them. it is where the firewall gussets are fitted. perhaps the load was created because of a hard landing or engine vibration. the lower center engine mount supports takes most of the compression load upon landing because they are the shortest and straightest and that makes them the stiffest. I'll have to keep an eye on those.
Based on the observation that the paint is breaking at the inboard half of the rivet head; I believe the inner lower mount firewall gussets flexes inwards during landing.... and this would be expected motion for the gusset geometry and applied mount loading, pivots around the gusset corner.
If you are in the market for an RV, this could be one place to inspect during the pre-buy. this is the first sign of any distress on this airframe. note: I have the old-style nose gear and do NOT land on anything other than a hard paved surface.
