MOSCOW. April 17 (Interfax-AVN) - The Motor scientific and production enterprise located in the city of Ufa, southern Urals, has developed a new version of the R-95Sh turbo-prop engine to be mounted on mass-produced SU-25SM and SU-25BM Frogfoot attack planes, Motor Designer General Alexander Ivak told Interfax- Military News Agency on Wednesday. Ivak said that the engine had been designed on order of the Russian Defense Ministry. The upgraded R-95Sh aircraft engine is fitted with the new PGL40-2SM gear generator ensuring reliable power supply of the aircraft, the voltage of the alternating three-phase current being 115V, frequency mounting up to 400Hz. Employment of the generator has resulted in considerable improvement of the aircraft's combat capabilities. In addition to that, the engine is fitted with a new system preventing stalling of the engine once in-board armament assets are used. Ivak said that the system had enabled experts to eliminate one of the drawbacks of the SU-25 Frogfoot aircraft. Pilots had to drop speed for some six seconds during combat application in order to prevent stalling of the aircraft's engine, which restrained combat capabilities of the aircraft, especially if it was used in mountainous terrain. The results of the trials carried out at the Chkalov State Flight Test Center in the town of Akhtubinsk, Astrakhan region, showed that the problem had been efficiently solved. The R-95Sh turbo-prop engine was developed at the Motor enterprise. A total of 70 types of engines and their versions have been designed at the enterprise, 21 of them mass-produced. Serial production of the R-95Sh engine for the SU-25 aircraft's powerplants is carried out at the Ufa engine building consortium. The upgraded R-95Sh engine is exhibited at the Dvigateli 2002 international exhibition that is being held in at the All- Russian Exhibition center in Moscow.