in fixed-wing mode. The third and fourth prototypes successfully completed the first sea trials on in December 1990. The fourth and fifth prototypes crashed in 1991–92. From October 1992 to April 1993, the V-22 was redesigned to reduce empty weight, simplify manufacture, and reduce build costs; it was designated V-22B. Flights resumed in June 1993 after safety changes were made to the prototypes. Bell Boeing received a contract for the engineering manufacturing development (EMD) phase in June 1994. The prototypes were also modified to resemble the V-22B standard. At this stage, testing focused on flight envelope expansion, measuring flight loads, and supporting the EMD redesign. Flight testing with the early V-22s continued into 1997. Flight testing of four full-scale development V-22s began at the Naval Air Warfare Test Center, Naval Air Station Patuxent River, Maryland. The first EMD flight took place on 5 February 1997. Testing soon fell behind schedule. The first of four low rate initial production aircraft, ordered on 28 April 1997, was delivered on 27 May 1999. The second sea trials were completed onboard in January 1999. During external load testing in April 1999, a V-22 transported the lightweight M777 howitzer. In 2000, there were two fatal crashes, killing a total of 23 marines, and the V-22 was again grounded while the crashes' causes were investigated and various parts were redesigned. In June 2005, the V-22 completed its final operational evaluation, including long-range deployments, high altitude, desert and shipboard operations; problems previously identified had reportedly been resolved. U.S. Naval Air Systems Command (NAVAIR) worked on software upgrades to increase the maximum speed from to , increase helicopter mode altitude limit from to or , and increase lift performance. By 2012, changes had been made to the hardware, software, and procedures in response to hydraulic fires in the nacelles, vortex ring state control issues, and opposed landings; reliability has improved accordingly. An MV-22 landed and refueled onboard in an evaluation in October 2012. In 2013, cargo handling trials occurred on . In October 2015, NAVAIR tested rolling landings and takeoffs on a carrier, preparing for carrier onboard delivery. Controversy Development was protracted and controversial, partly because of large cost increases, some of which were caused by a requirement to fold wings and rotors to fit aboard ships. The development budget was first set at US$2.5 billion in 1986, increasing to a projected US$30 billion in 1988. By 2008,