Recently, my aircraft management company SAMMwas managing the annual inspection of a client's piston-powered, single-engine airplane at a well-known maintenance facility in Texas. The inspection found very little wrong with the airplane, and it looked like the annual would be completed quickly and inexpensively. Then, quite unexpectedly, the IA responsible for the annual went to work for another shop, and a new IA was assigned to take over. Things quickly went downhill after that. The new IA informed us that he would not be able to sign off the annual unless we agreed to have both TCM/Bendix S-20 magnetos overhauled or replaced, something that would add nearly $2,000 to the cost of the annual and delay its completion by at least a week. He stated that the magnetos were required to be replaced or overhauled because they had been in service for more than 4 years. We told the IA we saw absolutely no reason to overhaul or replace the magnetos, and would not approve this work. The IA stubbornly refused to sign off the annual unless this work was done. After several back-and-forth iterations, it became obvious that we were at an impasse with the IA. At that point, we took the only reasonable course of action available to us under the FARs: We directed the IA to sign off the annual with discrepancies, obtained a ferry permit from the local FSDO -- allowing the aircraft to be flown back to its home base -- and then had a local A&P make logbook entries clearing the "non-discrepancy discrepancy" that the IA had recorded, and approving the aircraft for return to service. (The local A&P saw no reason to overhaul or replace the mags either.) For what it's worth, the TCM/Bendix magnetos on my own Cessna T310R have not been replaced or overhauled for 18 years, and I do not plan to overhaul them until the engines are overhauled. I do regular 500-hour disassembly inspections of the mags and that's all that I consider necessary. Most mechanics would agree with this approach.
This is a companion discussion topic for the original entry at https://www.avweb.com/ownership/the-savvy-aviator-63-recommended-or-required