To prepare the dressing, combine the milk, mayonnaise and spicy ranch packet in a bowl. Mix really well. Set aside.
Prepare pasta according to package directions and allow to cool. To cool quicker, place pasta in strainer and run cool water over pasta for about 2-3 minutes.
When ready to make salad, in a large serving bowl combine the cooked pasta and black beans.
Stir in the prepared dressing mixing well to coat.
Gently fold in the chopped avocados, cilantro and lime juice.
Cover and refrigerate. Chill 30 minutes to thicken.