The Y-12 started life as a development of the Harbin Y-11 airframe. The design featured numerous improvements including a redesigned wing with a new low drag section, a larger fuselage and bonded rather than riveted construction.
The first prototype i.e. (I) version flew on 14 July 1982, only 3 (I) version planes were built including the fatigue test one. This was designated the Y-12 (II), which featured more powerful engines and removal of leading edge slats, first flying on 16 August 1984 and receiving Chinese certification in December of the following year. The powerplants are two Pratt & Whitney Canada PT6A-27 turboprops with Hartzell propellers. The Y-12 has a maximum payload of 5,700 kg (12,600 lb) with seating for 17 passengers and two crew. The aircraft is operated as a light commuter and transport aircraft.
Y-12 (I) : Twin-engined STOL utility transport aircraft, powered by two 500-shp (373-kW) Pratt & Whitney Canada PT6A-11 turboprop engines. Prototype version.
Y-12 (II) : Fitted with more powerful PT6A-27 engines.
Y-12 (III) : Planned version to be fitted with WJ-9 turboprop. Evolved to Y-12C because of IV's success when WJ-9 development was completed.