chrispratt
Well Known Member
I'm curious if any other RV-8 flyers with the normally aspirated engine cowl have encountered this problem. I have the Lycoming O-360 engine with Van's FAB 360 air box. At about 150 hours, I noticed a slight crack in the exterior paint on the lower cowl air intake section (left side).
When I looked inside the cowling I saw four small round indentations in the heat shield material I had stuck to the cowling (see image).
It was obvious that the rivet heads on the air box nearest the cowling had impacted and caused this. I never saw this before the 150 hour point and I remove the cowl every 25 hours and check for stuff like this.
My solution was to drill out the four rivets that were at the apex of the curve in the air box and replace them with countersunk rivets. The thought was that the smooth heads would have less exterior depth. After another 25 hours of flight, I removed the cowl and I still noticed some indentations in the new heat shield (replaced after the last inspection) although the indents were not as prominent. Not sure what's causing this. Someone suggested that it may be happening when the engine does its "wet dog shake" on shutdown. Certainly possible. I'm still monitoring and will update when I figure out the cause, or better yet, the solution.
I would appreciate hearing from anyone else who may have experienced this and if they have a solution. Thanks.
Chris
When I looked inside the cowling I saw four small round indentations in the heat shield material I had stuck to the cowling (see image).
It was obvious that the rivet heads on the air box nearest the cowling had impacted and caused this. I never saw this before the 150 hour point and I remove the cowl every 25 hours and check for stuff like this.
My solution was to drill out the four rivets that were at the apex of the curve in the air box and replace them with countersunk rivets. The thought was that the smooth heads would have less exterior depth. After another 25 hours of flight, I removed the cowl and I still noticed some indentations in the new heat shield (replaced after the last inspection) although the indents were not as prominent. Not sure what's causing this. Someone suggested that it may be happening when the engine does its "wet dog shake" on shutdown. Certainly possible. I'm still monitoring and will update when I figure out the cause, or better yet, the solution.
I would appreciate hearing from anyone else who may have experienced this and if they have a solution. Thanks.
Chris
