SSIS Derived Column Transformation Editor

In my SSIS package,
I am using the below expression in SSIS Derived Column Transformation Editor to find - RTC in column 0.
FINDSTRING([Column 0]," - RTC",1)

What I really need to find is if column 0 contains:
RTCA or RTCB or RTCC or RTCD etc... all the way thru RTCZ

Is there a way to do that ?

column 0 is 80 bytes long and RTCA thru RTCZ can be anywhere in column 0