Have you installed the UT3 Bonus Pack?  Get it here:
http://utforums.epicgames.com/showthread.php?t=608057
Those files should be in the program files directory path
c:\program files\UT3\UTGame\CookedPC\Sounds\A_Vehicle_Cicada.upk
&amp;
c:\program files\UT3\UTGame\CookedPC\Vehicles\VH_Cicada.upk