It is designed for installation on the Mi-38/38-2 helicopters with engines PW-127T/S (VR-38) or ТV7-117V (VR-382). Purpose: transfer of power from two engines to the main, tail rotors and helicopter accessory with the corresponding change of the rotation speed.
Type of gearbox – multi-flow, 4-step, modular.
The main gearbox VR-38 has been designed in accordance with the certification basis requirements of the aviation regulations AP-29 and JAR-29. The multiflow design scheme provides the increased reliability of the gearbox, the minimal mass for the given class of helicopters, the layout requirements for the underhood helicopter space.
MAIN TECHNICAL SPECIFICATIONS
|Input shaft ration speed, nominal, RPM||19017,1||17150|
|Power being transferred by gearbox:
|Nominal shaft rotation speed of main rotor, RPM||195||195|
|Maximal torque on the shaft of main rotor, kgf ×m||15500||18400|
|Assigned resource (design), hour||12000||12000|
|Resource till first repair (design), hour||2000||2000|
|Mass, of gearbox without the rotor brake and subreduction frame, kg||880||910|
|Overall dimensions, LxWxH, mm:||1800х1200х1800||1950х1350х1800|
Developer: JSC “Krasny Octiabr”
High technical and operating parameters of the gearbox are achieved due to the following:
- the drive gearbox of helicopter accessory has an independent area operating both from the main drive and from the auxiliary drives (the power unit mode of the power plant) without engaging of the main module (VR-38),
- the power of the emergency mode of the engine is distributed over all flows of the main module,
- the power being transferred to the tail rotor and the drives avoids the main module and, accordingly, reduces the mass of the gearbox,
- gearboxes VR-38 and VR-382 differ in input modules; due to the replacement of the input module of the gearbox, one can use the engines with another rotation speed and direction of the input shafts,
- the independent drive gearbox allows to operatively change the complete set of drive accessory for various helicopter modifications.
The diagnostics system of the main gearbox VR-38 comprises:
- the system for detection of the kinematic chain uncoupling with the defect location diagnostics,
- chips falling out location analyzer using the helicopter onboard computer,
- the system for calculation of equivalent non-failure operating time.
The developed diagnostics system, modular design allowing to conduct repairs by module replacement (including during the operation), relatively low stresses in the gearbox parts allow to widely use the leader operation and the operation by inspection of technical condition.