Russia’s intention to replace the French-Russian SaM146 engines in its current Superjet 100 fleet with the domestically developed PD-8 may appear to be a simple solution to a significant aviation issue. However, recent evaluations by aviation specialists indicate that the process of re-engining older Superjets may be much more complex and costly than the simple process of removing one engine and installing another.
The issue is becoming more important as Russia aims to maintain the operational status of its current Superjet fleet while simultaneously introducing the entirely import-substituted SJ-100. The PD-8 is designed to remove the SaM146’s international support and supply chain, which became increasingly problematic after sanctions disrupted cooperation with Western suppliers. The United Engine Corporation has initiated the delivery of production PD-8 engines for Superjet aircraft, and the new engine has already entered serial production.
Nevertheless, Andrey Patrakov, the founder of the flight-safety service RunAvia and a former Safran employee, has stated that the installation of PD-8 engines on older Superjets would not solve all of the aircraft’s issues.
Replacing the engine is not enough
Patrakov argues that the original Superjet cannot be treated as an aircraft whose only major limitation is its powerplant. Substantial modifications to other aircraft systems would also be necessary for a large-scale conversion to PD-8.
This makes the economics particularly difficult. A program that includes approximately 50 aircraft could incur a cost of approximately 115 billion rubles, which equates to approximately 2.3 billion rubles per aircraft, as per estimates cited by The First Technical. The financial justification of reengining an aging airframe is called into question at that point, as the cost is comparable to that of developing or procuring a newer import-substituted aircraft.
This is the central distinction between the SJ-100 programme and a hypothetical PD-8 conversion of older Superjets.
From the outset, the SJ-100 was intended to incorporate major changes to its systems, avionics, and components along with the PD-8. However, retrofitting an aircraft that was originally designed around the SaM146 necessitates the integration of a much different propulsion system into an existing platform, followed by the demonstration that the modified aircraft remains safe in a variety of circumstances.
The PD-8 is not a copy of the SaM146. It is a Russian turbofan that was created to replace the Franco-Russian engine and is based on technologies associated with the PD-14 family. The powerplant is designed to offer Russia an autonomous propulsion solution for the SJ-100 and other aircraft programs.
The biggest question may be inside the engine
Patrakov has also identified another area that requires special attention: the hot segment of the PD-8.
The hot section of the engine was the responsibility of the French team in the original SaM146 program. In a turbofan, that section operates under some of the most severe thermal and mechanical conditions. Consequently, the combustion chamber and turbine blades are among the components that are subject to particularly rigorous requirements.
Russia has now developed these critical areas independently.
That is a major technological achievement; however, it also implies that Russia’s capacity to maintain a modern civil turbofan in real-world operating conditions without the engineering and industrial support provided by its foreign partner will be put to the test.
Development, flight testing, and serial production of the PD-8 have been completed at a fast pace. However, the ultimate evaluation of civil aviation engines is not only based on certification tests or initial flight performance but also on their ability to operate consistently over thousands of hours, in a variety of climates, maintenance regimes, and operating conditions.
Digital modelling cannot replace real-world testing
Another warning concerns the growing reliance on computer modelling during aircraft and engine development.
Modern digital engineering has the potential to significantly shorten development cycles and decrease the number of costly physical tests that are necessary during the initial stages of design. However, Patrakov contends that modeling cannot ensure that an aircraft will behave as anticipated during an unusual accident sequence.
His example comes from the original Superjet. It was reported that computer calculations predicted a specific pattern of fuel behavior in the aftermath of severe landing-gear damage, but real-world incidents have shown that fuel can behave differently.
This lesson is especially relevant to the SJ-100. Although a mathematical model can accurately replicate known physical conditions, aviation accidents frequently involve a variety of events that are challenging to predict, such as hard landings, repeated impacts, crosswinds, runway obstacles, structural deformation, and fuel-system damage that occur simultaneously.
The SJ-100, which is powered by the PD-8, still necessitates extensive full-scale testing for certification. The digital model is a valuable instrument; however, it is unable to replace the necessity for physical evidence.
Russia faces a strategic choice
The PD-8, therefore, symbolizes two separate concepts.
The SJ-100 is the focal point of Russia’s endeavor to develop a regional aircraft that is autonomous and not reliant on foreign propulsion or components, as was the case with the original Superjet. However, it may not be an economically viable rescue mechanism for aircraft powered by the SaM146 that are older.
The destiny of Russia’s regional aviation fleet could be influenced by that distinction.
Operators may find it more logical to allocate resources to the production of new SJ-100s rather than the extensive refurbishing of older airframes if retrofitting older aircraft necessitates extensive structural, systems, and certification work, which can cost billions of rubles per aircraft.
Consequently, the PD-8’s success will be evaluated on two fronts: whether it is dependable in long-term service and whether the SJ-100, which is constructed around it, can develop into a commercially viable aircraft.