Below is the list of tables from the database along with their columns and datatype. Need to generate an accurate SQL query for the question.
Only use the columns present in the respective table. Only use the columns which are required to generate the SQL query. Only use table joins if required and not otherwise.

### Tables ###
TABLE: CREATE TABLE table_name_14 ( build_date VARCHAR, prr_class VARCHAR, builder’s_model VARCHAR )

### Question ###
When was the build date for ff20 PRR class and erie built builder's model?

### Accurate SQL ###

SELECT build_date FROM table_name_14 WHERE prr_class = "ff20" AND builder’s_model = "erie built"