The spars of a Mitsubishi Zero are a nightmare to a warbird restorer.
Made of Extra Super Duralumin, an aluminum alloy, the spars are light and strong but very susceptible to the elements and corrosion. After years outside, the Zero’s spar often looks like the crisp, flaky center of a Butterfinger candy bar. Other wrecks have no spars at all — the metal has just melted away leaving slots in the wings.
To make a flyable Zero, one has to tear the plane down to its basic components to replace the troublesome spars.