What can easily happen in a crash, or even a "nose over" landing, is the metal plug cap takes a hit. That forces it to move rearwards momentarily and the connector end of the plug pokes a hole through the silicone insulation inside the plug cap. It can be invisible to see, but can cause the ignition to not work because the spark jumps through the insulation to ground instead of through the plug to make a spark for the engine to run. Check the "stickies" in the beginning of the forums for a post made by Jodi showing all the steps for checking the ignition. It's an excellent and informative post. Keep in mind though, that it is entirely possible for an ignition to show a visible spark when testing, but still not make the engine run properly. Been there, done that......
AV8TOR