Russian airline S7 is set to commence testing of its newly developed APD-520 “Leader” aircraft engine during the summer of 2025, according to reports from Russian media outlets.
The APD-520 engine is an in-house creation by S7 Technics, the maintenance and engineering arm of Russia’s largest private airline, designed to power the “Tango” light aircraft.
The Tango, a four-seat composite aircraft developed by Spectra Aircraft Design Bureau—also part of the S7 group—weighs approximately 1,200 kilograms and can reach speeds up to 241 km/h with a maximum range of 1,100 km.
Having made its maiden flight in September 2024, the Tango is still undergoing development. Initially equipped with a Belgian-made UL Power UL520is engine, S7 announced in November 2024 the decision to replace it with the domestically manufactured APD-520.
The APD-520 is an air-cooled, six-cylinder, 5.2-liter engine delivering 200 horsepower and boasting an expected service life of 1,500 hours between overhauls. Final technical specifications will be confirmed after the test phase concludes.
Publicly unveiled at Russia’s National Aviation Infrastructure Salon in February 2025, serial production of the APD-520 is slated to begin in 2026, with plans to manufacture 30 units in its first year.
Primarily targeting the flight training sector, the Tango’s chief customer is expected to be the Russian Ministry of Transport, which oversees more than half of the country’s flight schools through the aviation regulator Rosaviatsia.
Russian media reports indicate that governmental bodies may order up to 250 Tango trainers to replace and augment existing fleets of foreign aircraft such as the Cessna 172 and Diamond DA40, which have become increasingly difficult to maintain amid ongoing sanctions restricting parts and spares.
Beyond the Tango and APD-520 program, S7 has been actively pursuing import substitution initiatives to reduce reliance on Western components for larger aircraft. In October 2024, the group began producing jet engine fan blades in Novosibirsk, Siberia, though plans for an engine parts factory in Saint Petersburg were suspended earlier this year.
This push for domestic aerospace capability reflects Russia’s strategic focus on strengthening self-sufficiency amid global geopolitical pressures.