hi irishflyer ,
it could be a couple of things 1/ is the aileron servo secure ? they have a trend of becoming loose and flopping round a bit 2/ do you use the radio that came with it or a branded one eg futaba , JR etc ? it could be the radio you may be exceeding its range ...do any of the other controlls play up ? 3/ have you checked the ailerons themselves one could be sticking or the tape could be binding somewhere .Other than that I cant think of anything else , its strange if it only wont turn right .Hope this helps .My Cessna is flying great and have had many great flights with her ...25+ Flights .

cheers
V-S