There were 2 occurrences of cracks developing in the leading edges of the horizontal stabilizer. Both of these were on a/c with UL Power 130 engines. The factory developed a fix to ameliorate the harmonics that caused the problems.
1. Add a doubler skin to the leading edge 2. Double the number of rivets along the ribsw 3. Add elevator hinge extension pieces
Today I did the first two steps, plus some. Drilling out the rivets for the leading edge doublers was easy, as was riveting new doublers in place. Same for drilling new rivet spacing for the extra rib rivets.
A lot of time was then spent trying to get the drilled-out rivet shop heads and shavings out of the stabilizer. There are no holes in the tail for them to escape, so the factory recommended drilling-out the rear spar rivets, prying open the sking-to-tpsar junction, and shaking them out. I did this, ha to expand the range of drilled rivets, and still it was hard to extricate theblasted rivets.