There's a known bug with older version of the OpenGPWS plug-in that causes a crash when you load a plane that uses that plugin with the XP12 version of the OrbX True Earth UK Scenery Installed.
Fortunately there is a fix so if you apply the updated version of the OpenGPWS plugin from this post it should get the plane back up and working again, (though a new version of the installer loading the corrected plug-in by default would be preferable)
-- Edit --
If you have the RSG G500 Avionics plug-in, you'll need to reapply the OpenGPWS fix after installing the G500 in the Sundowner Directory as that reinstalls the old version