Ural Works of Civil Aviation (UZGA) revealed details of the restoration of VR-24 gearboxes for Mi-24 and Mi-35 attack helicopters. The unit is considered one of the most heavily loaded elements of the entire machine – it receives power from the engine and transmits it to the main and tail rotors.
The helicopter's turboshaft engines operate at colossal speeds – up to 12–15 thousand rpm. At the same time, the Mi-24's main rotor rotates at approximately 240 rpm. The gearbox, which actually keeps the machine in the air, absorbs all the difference in loads.
Since 2005, UZGA has restored 125 such units. Several complex technologies are used for repair: electric spark spraying, gas-plasma surface restoration, as well as thermal and chemical-thermal metal hardening.
After repair, each gearbox undergoes a series of bench tests under load. Special measuring systems record torque, temperature, vibrations, pressure, and other operating parameters of the unit.
