Posted for "Rick Argente" <ricargente@cs.com>:

 Kevin,
 
 I had the same exact problem when I was test flying my 360.  The
 solution was to stiffen the trailing edge of the ailerons (cup section).
 I stiffened this section by installing one half-moon rib in the middle
 section of each aileron (aka flaps).  After this mod, wala, aileron
 vibration was gone!
 
 Rick Argente