There are NO FAA minimum formal educational requirements to become a civilian helicopter pilot.  The FAA does require, however, that you are able to read, write, speak, and understand the English language.  So you must be able to read well enough to pass the FAA written "knowledge" test(s).  Some simple math ability is also required to figure out helicopter weight and balance and flight planning questions.  So you don't even need a grade school education as long as you can learn to answer the questions on the FAA written "knowledge" tests.