sentences:  During the 1980s, there was considerable interest within French aerospace manufacturer Aerospatiale to further develop their successful AS350 B3 Écureuil rotorcraft, which had been originally developed in the early 1970s.On 6 February 1987, a prototype AS350 Z (a modified AS350 B2) conducted its first flight with a Fenestron tail-rotor fitted in the place of its conventional counterpart.The AS350 Z test program stretched across several years, the aircraft receiving additional modifications such as a new air intake based on that of the Eurocopter EC120.