Yingling price is $50,000 to install spar strap on Cessna 400 series planes. On planes with mid-high time engines with steam gauges with need for paint and interior, that $50,000 for a spar strap basically makes the plane worth more as scrap metal and parts than trying to repair and fly. Cessna 421 with dangerous starter-dampener problems that requires 400 hour inspections of gear teeth and replacement if teeth show wear to prevent the engine from disintegrate in seconds if the starter dampener fails, is scary and may not be worth the risk.