Brief Description: Vans issues Svc Bulletin on Stabilizer Spar
My horizontal stabilizer has not been mounted yet and Vans issued a Service Bulletin stating that you must check for cracks in the four corners of the forward spar-to-rib/skin connection. Their highly used RV-7A demo had some. VAF board is full of mis-guided (IMHO) comment about this subject, mixed in with some good responses. Bottom line is we are to check for cracks, fix them with Vans provided doublers. If no cracks are found, continue to check annually. One pilot with 3000+ high stress hours reported no cracks. One low time plane with couple hundred hours had a crack. Go figure. Much discussion about how earlier planes (RV6s and some RV7s) did not have any stress relief circular notch in the affected corners of the spar where the spar goes from vertical to horizontal and gets squeezed between the skin and a rib flange. Mine look fine and I am not doing the doubler until inspection shows a crack, if ever. Many many older planes report no cracks and no circular notch like Vans added to the RV-7 plans later in the game. Some say the relief notch itself causes the crack to develop. I don't know. I'm just going to inspect annually. The fix is complex with good chance of buggering an existing hole when you have to remove about 120 or so rivets to fix.
