The Y-12 started as a development of the Harbin Y-11 airframe called Y-11T in 1980. 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, followed by about 30 production Y-12 (I) aircraft before a revised version was produced. 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 power plants are two Pratt & Whitney Canada PT6A-27 turboprops with Hartzell propellers. The Y-12 has a maximum takeoff weight 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.
The latest development is Y-12F, which is almost a new design with many improvements: new wings, new landing gears, new fuselage, with more powerful engines from Pratt & Whitney Canada and extended payload and range. The Y-12F made its maiden flight on December 29, 2010, received the CAAC type certification on December 10, 2015, and the FAA type certification on February 22, 2016. In 2015 Kenmore Air announced that they would begin development of floats for the Y-12 for FAA certification.The Y-12 completed the FAA evaluation flight tests for its automatic flight control system on June 30, 2018, with its performance meeting the requirements, said AVIC Harbin Aircraft Industry Company Ltd (AVIC HAFEI).
Harbin Y-12 (II) at China Aviation Museum, Beijing
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.
Y-12 (IV): Improved version. Revised wingtips (span increased to 19.2 m (63 ft)) and increased takeoff weight. 19 passenger seats. This version is the first aircraft in the series certified by the FAA in 1995.
Y-12C: Basically a (IV) version with WJ-9 turboprop, now used by PLAAF for aerial survey.
Y-12D: Domestically deployed military version with upgraded engines driving four-bladed propellers, now used by PLA Airborne Corps for parachute training.
Y-12E: Variant with 18 passenger seats. PT6A-135A engines of equal horsepower but increased torque driving four-bladed propellers. This version was certified by the FAA in 2006.
Y-12F: The latest development with almost everything redesigned: wider fuselage, new wings, retractable landing gear and more powerful PT6A-65B engines. The Y-12F has higher cruise speed, longer range and can accommodate 19 passengers or 3x LD3 containers. Design started in April 2005 and the maiden flight was on 29 December 2010.CAAC type certification was received on 10 December 2015 and FAA certification on 22 February 2016. The Y-12F aloso passed flight tests for its automatic flight control system by the FAA on 30 June 2018. It has been also demonstrated during the 2012 Zhuhai Airshow.
Y-12G: Proposed cargo version of Y-12F.
Turbo Panda: Export name for (II) version, marketed by England and Japanese companies. No real order due to airworthiness certification.
Twin Panda: Originally (II) version for export. Later a modified Y-12 (IV) powered by two Pratt & Whitney Canada PT6A-34 turboprop engines and fitted with uprated undercarriage, upgraded avionics and interior. Thirty-five orders reportedly received by 2000 but production not proceeded with.
On 13 December 1993, a Lao Aviation Y-12-II, registration RDPL-34117, clipped trees in fog and crashed at Phonesavanh, Laos, killing all 18 on board.
On 4 April 1995, a TANS Y-12-II, registration 333/OB-1498, crashed shortly after takeoff from Iquitos Airport, Peru, killing all three on board.
On 21 June 1996, a China Flying Dragon Aviation Y-12-II, registration B-3822, crashed into a 100 m (330 ft) mountain near Changhai Airport after the crew began the final approach too early and deviated from the intended course, killing two of 12 on board.
On 20 January 1997, a Sri Lanka Air Force Y-12-II, CR851, crashed off Palali Air Base while on a surveillance mission, killing all four on board.
On 26 May 1998, a MIAT Mongolian Airlines Y-12-II, registration JU-1017, crashed into a 10,800 ft (3,300 m) mountain near Galt, Mongolia en route to Tosontsengel due to heavy icing, wing de-ice system fault and overloading, killing all 28 on board; this crash is the worst ever accident involving the Y-12.
On 19 October 2000, a Lao Aviation (now Lao Airlines) Y-12-II, registration RDPL-34130 and operating as Flight 703, crashed in a mountainous area in bad weather while on approach to Sam Neua, killing eight of 15 passengers; both pilots survived.
On 18 May 2005, a Zambia Air Force Y-12-II, AF-216, crashed shortly after takeoff from Mongu Airport, killing all 13 on board.
On 10 April 2006, a Kenya Air Force (KAF) Y-12-II, 132, struck the side of Mount Marsabit, killing 14 of 17 on board.
On 15 June 2008, a China Flying Dragon Aviation Y-12-II, registration B-3841, struck a small hill during a survey flight for a new aluminum mine, killing three of four on board.
On 12 July 2012, a Y-12-II of the Mauritanian Air Force crashed while transporting gold, killing all 7 occupants.
On 12 May 2014, a Y-12-II of the Kenyan Air Force crashed in El Wak, Kenya. The airplane operated on a flight from Mandera to Nairobi with stops at El Wak and Garissa. Preliminary information suggests that one pilot was killed and the remaining eleven occupants were injured.
On 26 August 2018, a Y-12e of the Colombian airforce was damaged in flight as it encountered severe turbulence. The pilot made an emergency landing at Florencia. The aircraft was not repaired, and was scrapped in situ. 
On 3 January 2020, a Y-12-II of the Sri Lankan Air Force crashed to Haputale, Sri Lanka, while on aerial observations, killing all 4 airmen.
Specifications (Y-12 (II))
Data from Brassey's World Aircraft & Systems Directory 1999/2000, Jane's all the World's Aircraft 2000-01
Capacity: 17 pax / 1,700 kg (3,748 lb) max payload