Word Pruning by Letter Subtraction

subtract_letters.rb

possible_words = ["seek", "find", "ignore", "pursue", "covet"]
available_letters = ["a", "c", "e", "f", "g", "i", "n", "o", "p", "r", "t", "u", "v"]

words = Array[possible_words].flatten
available_letters.each {|e| words = words.map {|w| w.sub(e, '')}}

viable_words = words.each_with_index.collect {|w,k| possible_words[k] if w==""}.compact

word_as_hash = Array.new
viable_words.each do |word|
i = 0
x = word.size
while x > i
word_as_hash << word[i].to_sym
i += 1
end
end

okay so that successfully changes each character to a hash but doesn't keep the words as separate arrays. Ideas?