United Aircraft acknowledges that it is having to work its way around delays to the domestically-built Aviadvigatel PD-8 engine as its progresses with flight-testing the Yakovlev SJ-100.
The SJ-100 is a version of the Superjet 100 adapted to feature a higher proportion of Russian-build components and systems.
These include PD-8 powerplants intended to replace the Franco-Russian PowerJet SaM146.
The SJ-100 carried out its maiden flight in August 2023, with flight-certification tests commencing from Moscow’s Gromov institute in June this year.
But while the initial prototype, number 97021, has a number of domestically-sourced systems, it is still fitted with SaM146 engines.
United Aircraft says the certification timeline for the aircraft has “shifted relative to initial plans” and that the “main reason” is delays in developing the PD-8, which is undergoing bench tests.
SJ-100 chief designer Kirill Kuznetsov, in remarks posted by the aerospace firm, says the PD-8 situation has “significantly affected” the manufacturer’s plans.
Once the engines are ready, United Aircraft intends to introduce two more SJ-100 prototypes to the certification programme and intensify the campaign. The aircraft are awaiting PD-8 installation at Komsomolsk-on-Amur.
Kuznetsov says the PD-8 is required to assess not only engine performance but the aircraft-engine combination – including take-off and landing characteristics, and interaction between the powerplant and other systems.
“We are trying to fly systems and components on the first prototype aircraft…as much as possible,” he adds. “The aim is to give our subcontractors the opportunity to complete their qualification work and freeze the design.
“It is important for us that the production of equipment to complete serial aircraft does not require any additional modifications.”
The company is trying to minimise the possibility of problems emerging during flight tests by conducting a substantial proportion of engine and system interfacing checks on ground stands.
Kuznetsov estimates that the volume of basic SJ-100 aircraft testing will amount to only 30-40% of that carried out during certification of the Superjet 100, because much of the architecture and the system interfaces are unchanged.
“A significant part of the checks do not require reconfirmation,” he says, notably those relating to aerodynamics and stability.
But the aircraft and systems combination will demand close to the same quantity of testing as conducted for the Superjet 100. Strength testing of the airframe is being conducted to validate changes devised during the last 15 years of Superjet development.
Kuznetsov adds that there are issues to address when integrating new domestically-sourced systems in the aircraft, including lack of experience and the need for repetitive practice to keep tests on schedule.
