The Ilyushin Il-12 (NATO reporting name: Coach) is a Soviet twin-engine cargo aircraft, developed in the mid-1940s for small and medium-haul airline routes and as a military transport.
Design and development The Il-12 was developed as a private venture by the Ilyushin Design Bureau from autumn 1943 and was intended as a replacement for the Lisunov Li-2, a license-produced version of the Douglas DC-3. Initial studies proposed a 29-seat airliner powered by four supercharged M-88V engines (as used in the Ilyushin Il-4 bomber) and with a pressurized cabin, allowing the aircraft to cruise at an altitude of , with a range of at almost . The aircraft would be fitted with a tricycle landing gear, the first use by the Ilyushin OKB.
During 1944, the design was changed, with the M-88B engines replaced by two ACh-31 diesel V-12 engines (each producing at take-off). The plans for a pressurized fuselage were abandoned and the number of passengers reduced to 27. The lower operating altitude resulted in a reduction in the aircraft's range and cruising speed. The Il-12 made its maiden flight on 15 August 1945."Dates of Maiden Flights by Aircraft Designed by "Ilyushin" Design Bureau." Ilyushin Aviation Complex. Retrieved: 13 November 2010. It was soon decided to re-engine the aircraft with Shvetsov ASh-82 radial engines, as it was expected to take too long to develop the ACh-31 to an acceptable reliability and time between overhauls for commercial service. The modified first prototype flew with its new engines on 9 January 1946.
The Il-12 was found to have problems with vibration during testing, having poor engine out characteristics and requiring a strut under the rear fuselage to prevent tipping during loading due to centre-of-gravity problems. However, factory test pilots praised the quality of the new aircraft, with much better performance and handling than the Li-2, which contributed to the decision to launch the Il-12 in series production. One problem was the use of magnesium near the engines which, in case of engine fire, could cause an uncontrolled fire, damaging the wing structure. This was revealed by a crash of an Ilyushin Il-12 near Voronezh in 1949 which killed all on board, following an engine fire. Subsequently, as a result of the accident investigation, the magnesium was replaced by aluminium alloys and the fire extinguishing system was redesigned. In addition, the aircraft's takeoff weight was restricted to ease the hazard of an engine failure during take-off - this in turn reduced the aircraft's passenger capacity, which was temporary limited to 18.
The Il-12 was a low-wing cantilever monoplane, with a single fin and rudder and a retractable tricycle undercarriage. It was powered by two Shvetsov ASh-82FN radial engines, rated at for take-off and at , driving four-bladed propellers. The fuselage had a considerable volume, and was equipped with eight rectangular windows on each side. The crew consisted of three and the aircraft could transport 32 soldiers, 32 parachutists or cargo. There was also a civil version, which although designed to carry up to 32 passengers, was limited in Aeroflot service to 21, with normally only 18 carried. At that passenger load, it meant that use of the Il-12 for passenger use was un-economic.
A total of 663 Il-12s were manufactured. The aircraft was later improved into the Ilyushin Il-14.
Operational history
The Il-12 was revealed to the public on 1 May 1947, when a group of aircraft participated in the annual May Day flyby over Red Square in Moscow. Performance testing was completed by 20 May, and the first regular passenger service by the Il-12 on Aeroflot began in June 1947. The first regular international use of the Il-12 was on the Moscow-Sofia route in 1948. The Il-12 was used on Aeroflot's services to Paris from 1954.
Within the USSR, the Il-12 was placed on Aeroflot's longest route: Moscow-Khabarovsk, with the flight lasting 28 hours, including five refueling stops. From 1956, the Il-12 (modified for use on ice runways) supported the Soviet expeditions to Antarctica. Aeroflot continued to use the Il-12 on some routes until the end of 1970.
Export sales The first export customer for the Il-12 was LOT Polish Airlines, who placed an order for five Il-12Bs after it was displayed at the Poznan Fair in Poland in the spring of 1948. This was followed by Czech Airlines, who purchased 10 aircraft from 1949 to 1951, TAROM in Romania from 1949, and at least 20 aircraft to CAAC in China.
Variants Il-12A : Basic passenger version with 27 seats standard, also produced in versions with 6, 11, 16, 18, 21 seats. Il-12B : Modification from 1948, fitted with an improved de-icing system, lengthened nosewheel and a small dorsal fin fillet. Il-12D : military transport version for the Soviet Air Force launched in 1948, for 38 paratroops or military cargo to 3700 kg. Il-12P：A 32-seater passenger aircraft type. Il-12T : transport version for arctic operations, with a large cargo door on the left side of the fuselage.
Accidents and incidents
Of the 663 Il-12s produced, 56 have been lost in accidents with a total of 465 fatalities.
1940s 1 July 1947 An Aeroflot Il-12P (CCCP-Л1317) crashed on takeoff from Vnukovo Airport due to loss of speed following unexplained engine failure, killing four of six on board.
19 September 1947 An Aeroflot Il-12P (CCCP-Л1332) was struck by a crashing North American B-25 (CCCP-И850) that had lost control during an emergency landing at Vnukovo Airport; both aircraft burned out, but there were no casualties.
24 November 1947 An Aeroflot Il-12P (CCCP-Л1356) overran the runway on takeoff from Koltsovo Airport; all six crew survived. The aircraft was overloaded by and had not been properly de-iced.
1 December 1947 A Polyarnaya Aviatsiya Il-12 (CCCP-Н439) was on an unauthorized positioning flight from Kimry to Moscow when it force-landed near Taldom ( south of Borki Airfield) after the left engine lost power due to an oil leak; all five crew survived.
18 December 1947 Aeroflot Flight 6, an Il-12P (CCCP-Л1343), stalled and crashed near Severny Airport while attempting to land following a go-around due to engine failure, killing seven of 25 on board.
2 September 1948 An Aeroflot Il-12 (CCCP-Л1465) crashed on takeoff from Severny Airport after entering a descent when the flight engineer reduced engine power; a propeller blade broke off and penetrated the fuselage, killing one of 20 on board.
9 September 1948 An Aeroflot Il-12 (CCCP-Л1427) crashed near Baimakovo Aerodrome during a training flight following a loss of control, killing all four crew. The pilot was practicing flying with one engine out. The instructor feathered the propeller too soon after a go-around with the flaps deployed and the aircraft entered a banking turn with a loss of airspeed. Control was lost and the aircraft entered a dive.
12 October 1948 An Aeroflot Il-12 (CCCP-Л1450) disappeared over the Caucasus Mountains near Yevlakh with ten on board. After arriving at Baku, the flight was unable to continue to Tbilisi due to bad weather. The next day the aircraft left for Tbilisi, but the crew failed to check weather conditions along the flight route. The aircraft climbed to . En route the aircraft encountered navigation problems due to poor reception of radio beacons. The crew then decided to return to Baku but never made it. Last radio contact was near Yevlakh; the aircraft has never been found.
23 December 1948 An Aeroflot Il-12P (CCCP-Л1731) collided in mid-air near Valuyevo with an Aeroflot TS-62 (CCCP-Л861) that was being ferried from Vnukovo Airport to Bykovo Airport, killing all 12 on board both aircraft. The brand-new Il-12 was being handed over to a crew from Aeroflot's Georgian division, but when the crew failed to turn up in time, the aircraft was then handed over to a crew from the Uzbek division instead. The Il-12 then departed for Tashkent via Lyubertsy, although ATC did not know the change in the flight plan and assumed the Il-12 was going to land at Vnukovo. The Il-12 collided with the TS-62, breaking off both engines while the tail of the TS-62 was sheared off. ATC errors were blamed.
19 January 1949 An Aeroflot Il-12P (CCCP-Л1381) crashed shortly after takeoff from Stalino Airport (now Donetsk Airport) due to loss of altitude following engine problems, killing eight of nine on board; two people also died when the aircraft crashed into a house.
13 May 1949 Aeroflot Flight 17, an Il-12P (CCCP-Л1791), crashed during descent to Novosibirsk in bad weather due to loss of control following a lightning strike, killing all 25 on board.
21 July 1949 Aeroflot Flight 5, an Il-12P (CCCP-Л1714), crashed and burned in a forest near Marga while attempting a forced landing following an engine fire, killing 13 of 14 on board.
20 August 1949 An Aeroflot Il-12 (CCCP-Л1434) crashed near Polukotelnikovo after losing altitude in a downdraft, killing eight of 11 on board.
25 August 1949 An Aeroflot Il-12P (CCCP-Л1844) struck Mount Kabanya (20 mi south of Kabansk) following an unexplained descent from to , killing all 14 on board.
20 September 1949 An Aeroflot Il-12 (CCCP-Л1462) crashed near Savasleyka while attempting a forced landing following engine failure, killing three of four crew.
1950s 19 July 1950 An Aeroflot Il-12P (CCCP-Л1340) struck the top of a hill and crashed near Tbilisi Airport during a training flight after the pilot deviated from the glide scope and approach pattern, killing four of 11 on board; on board were six unauthorized passengers, all Tbilisi Airport employees. The hill that the aircraft hit was not indicated on the flight map.
30 July 1950 An Aeroflot Il-12P (CCCP-Л1803) crashed shortly after takeoff from Karaganda Airport due to loss of control following engine failure, killing all 25 on board. Six minutes after takeoff the crew radioed that engine number one had failed and that they were returning to the airport. While turning for final approach, the aircraft turned left (in the direction of the failed engine) and lost speed while lowering the landing gear. Control was lost and the aircraft spiraled down and crashed. The left engine was having problems before and after maintenance, but the crew operating the test flight failed to report the problem.
11 August 1950 Aeroflot Flight 8, an Il-12P (CCCP-Л1706), struck trees and crashed in a meadow while on approach to Koltsovo Airport in fog after descending below the glide scope due to pilot error, killing two of five crew; all 22 passengers survived.
9 January 1951 An Aeroflot Il-12P (CCCP-Л1811) crashed in the Black Sea off Tuapse following a fuel tank explosion and fire due to a lightning strike, killing all eight on board. The storm that the crew flew into was not forecast and a storm warning was issued some 40 minutes after the crash.
13 March 1951 An Aeroflot Il-12P (CCCP-Л1319) crashed near Koltsovo Airport following a loss of altitude during approach; there were no casualties.
29 March 1951 An Aeroflot Il-12P (CCCP-Л1313) crashed near Vnukovo Airport during a test flight following multiple diversions due to spatial disorientation caused by a malfunctioning radio compass, killing three of four crew; all four passengers survived.
14 November 1951 An Aeroflot Il-12P (CCCP-Л1360) crashed shortly after takeoff from Nikolayevsk-on-Amur following a loss of altitude due to pilot error; all 19 on board survived. The aircraft took off with moist snow on the fuselage that had accumulated during taxiing and engine tests. A late and slow takeoff caused the aircraft to vibrate and the flight engineer mistook the vibration for a rough-running engine and overfueled the left engine, and it lost power. Altitude was lost and the aircraft crashed.
17 November 1951 An Aeroflot Il-12P (CCCP-Л1775) lost control and crashed shortly after takeoff from Novosibirsk Severny Airport due to wing icing, killing all 23 on board.
21 February 1952