United Aircraft has suspended flight-testing of the Ilyushin Il-114-300 following the fatal accident involving a prototype of the military Il-112V.
Russian investigators have established a committee to look into the Il-112V crash, outside Moscow on 17 August, although it has yet to reach any preliminary findings.
But the Il-114-300 is powered by the Klimov TV7-117ST-01 engine, which is closely related to the TV7-117ST fitted to the twin-engined military transport.
Video images of the accident appear to indicate a fire in the Il-112V’s starboard engine before the aircraft banked to the right and rolled into a steep dive.
“It is necessary to conduct a thorough investigation of the Il-112V accident, especially an analysis of hard evidence from the flight-data recorder,” says United Aircraft, which is part of the state corporation Rostec.
“It is because of this that the flight-test programme for the Il-114, which has a similar powerplant, is temporarily suspended.
“The accident investigation committee has just commenced its work. It is too early to draw any conclusions at this point.”
Chief test pilot Nikolai Kuimov and senior test pilot Dmitry Komarov were among the crew lost on the Il-112V. Both had carried out the maiden flight of the Il-114-300 in mid-December last year, Kuimov stating afterwards that the aircraft had proven reliable despite the poor weather.
He participated in a joint panel at the MAKS Moscow air show in July which discussed publicly the testing of the Il-114-300 and Il-112V and their engines.
General designer of United Engine’s Klimov division Vsevolod Eliseev, speaking during the event, had expected the TV7-117ST-01 and its propeller to complete flight and certification tests in the first quarter of 2022. United Aircraft has been aiming to deliver Il-114-300s from 2023.
Klimov TV7-117 engine programme director Stanislav Konashkov says the powerplant has undergone a “huge quantity” of bench tests.
“But this is not the same as testing it as part of an aircraft, along with aircraft components, when the effect of all these systems on the engine is taken into account,” he told the panel audience.
The Il-112V – with the TV7-117ST engine – first flew in March 2019, but then underwent a substantial period of modification before resuming test flights in March this year.
United Aircraft has not indicated the extent to which either the Il-114-300 or Il-112V programmes might be disrupted, either by the technical investigation or the loss of its senior test crews.
The inquiry will attempt to understand why such experienced pilots – used to flying aircraft in abnormal and extreme conditions – lost control of the Il-112V and were unable to recover.
Video images show the aircraft flying level at low altitude, perhaps 500ft, before losing height as it entered a right bank, rolling sharply into an inverted dive.
The aircraft had been in Moscow to participate in the Army-2021 military exhibition.
Investigators have yet to explain the source of the fire or disclose any link between the engine situation and the crash, including whether the aircraft sustained damage to flight controls, or whether the engine was being shut down and its propeller feathered. The inquiry will also explore whether the bank was intentional, especially towards the side of the affected engine, and the reasons for the sudden loss of roll control.