The flight test program was conducted using the pair of prototypes produced, which had been assigned the serial numbers "94-0327" and "95-0001". Following a demonstration of its ability to meet certain key criteria, on 1 June 2000, the RAH-66 entered the $3.1 billion engineering and manufacturing development (EMD) phase of the program. Through the early 2000s, the U.S. Army maintained its plans for the intended purchase of over 1,200 Comanches, which were to fill both the scout helicopter and light attack roles; as late as 2003, it was being anticipated that deliveries of operational RAH-66s would commence as scheduled during 2006.