Just was out replacing a spar carry through on a Cessna 182, the problem was found during an annual inspection the culprit was an interior headliner that was glued to the spar carry through and moisture was caught between the fabric and the spar. This was the first annual for my customer on this plane, it had lived its life in south Texas. We found corrosion everywhere the headliner was glued to the interior, needless to say none of this was caught on his pre buy inspection. The new parts were purchased from Cessna, not cheap and took 6 weeks to get and just a few guide holes for help. We built a jig and measured may times but it all came in to place with no problems.
Cessna 180 only and sometimes a 182