The crash was caused by the XPlane plugin trying to add a child object to a non-existent (NULL) parent. I'm not sure how this could happen but perhaps it was an empty entry in the hierarchy?
Anyway, I've added a fix which (will stop the crash) into AC3D, which will be in the next AC3D release.
Here's your obj file fixed, which now imports and exports OK. If you find out the error in the original, please let me know.
www.inivis.com/external/painelAC.zip