The Sikorsky S-70 series was designed to meet a requirement of the US Army for a utility tactical transport aircraft system (UTTAS), winning a contest in 1976 against a design from Boeing Vertol.

The prototype of the EC-135 series (D-HECX) made its first flight at Ottobrunn, Germany on 5 February 1995, this being the first definitive aircraft following the completion of a test flying programme with two BO-108 technology demonstrators.