November 5, 1959 — after dropping from its B52 (520003) mothership, now housed at the museum, the X15 sustained a small engine fire forcing test pilot Scott Crossfield to make an emergency landing. However, not all the propellant was jettisoned and because the X15 wasn't designed to land with such a heavy payload, it broke the plane's back. Grounded for repair, it returned to the skies three months later. It suffered a second crash landing in 1962 but would return as the modified X15A2 that would eventually set the rocketplane speed record of Mach 6.7 in 1967.