Sum of even fibonacci numbers

Find the sum of all even fibonacci numbers that do not exceed four million

Warning, there's a slightly crude appending to an array below (I learn how to properly append in later exercises). findAll gets another working out:

fibos = []
a1 = 0
a2 = 1

while (true) {
   curr_term = a1 + a2
   if (4000000 <= curr_term)
      break
      fibos += [curr_term]
   a1 = a2
   a2 = curr_term
}

println fibos.findAll { it % 2 == 0 }.sum() // => 4613732