GlennBfromOz
Member
Hi all,
Yesterday a friend and I performed the repair as above, on each of our RV7s. Our idea was to do it pre-emptively, as that would avoid the need to open up the tailplane to install the repair doubler. We drilled out 6 rivets top and bottom each side to install the spar doublers, and riveted them in place. So far, so good...
We prepared the Cherrymax rivets for the new hinge brackets as indicated in the SB, by knocking the mandrels part way out and lubricating. Despite this, in about half of the cases the mandrel broke early. There are a couple of ways to know this happened, including the head of the mandrel not being flush with the rivet, but the real evidence is shown with a borescope on the inside of the tailplane spar. You can see the difference between the two rivets in the photo.
So, a few questions arise:
Glenn
Yesterday a friend and I performed the repair as above, on each of our RV7s. Our idea was to do it pre-emptively, as that would avoid the need to open up the tailplane to install the repair doubler. We drilled out 6 rivets top and bottom each side to install the spar doublers, and riveted them in place. So far, so good...
We prepared the Cherrymax rivets for the new hinge brackets as indicated in the SB, by knocking the mandrels part way out and lubricating. Despite this, in about half of the cases the mandrel broke early. There are a couple of ways to know this happened, including the head of the mandrel not being flush with the rivet, but the real evidence is shown with a borescope on the inside of the tailplane spar. You can see the difference between the two rivets in the photo.
So, a few questions arise:
- If the mandrel doesn't seat fully, how much are the grip and shear strengths compromised? If unacceptably so:
- Is this an immediate cause to drill out and replace the offending rivets? I note that the rivets appears properly bulbed on the inside, for what that's worth. And I'm acutely aware that removing the rivets invites the possibility of damage to the existing holes. And, if we do replace them:
- How do we ensure that the same thing doesn't happen again? I've never had this occur before when installing Cherrymax.
Glenn