Research Of Helicopter Main Gearbox Operating Without Oil

The transmission system is the one of the helicopter three critical assemblies.The main gearbox (shortened form is "MGB") is an important assembly of the transmission system. Although it is low probability failure for the MGB lubrication system, the MGB will under the hardest condition once it happened. The catastrophic accident will happen if the lubrication system of MGB failure----the lubricative and cooling condition become worsen, so it lead the temperature of the main drive parts raise rapidly, the MGB will be destroyed and doesn’t transfer power immediately. In order to ensure the safety of the helicopter, we hope that the MGB can work at least30min in the special condition when the MGB lubrication system failure. So it is very important to do the research of MGB oil loss capability. At present, there isn’t a ripe method to forecast the MGB oil loss capability exactly, the aim come true only depending on design experience, test, analysis and improvement. This paper fined out the weakness of MGB oil loss capability according to the thermal analysis and thoroughly tests. Finally, the MGB oil loss test succeeded after improvement the weakness.The main research findings are presented as follows:(1) Obtained the temperature of the main node by thermal network method.(2) It proven that the sliding friction is not good for oil loss capability according to the analysis and test. So we must take attention during design. The location or one component of MGB oil loss capability may influence the whole MGB oil loss capability. In order to improve the MGB oil loss capability, we must finding out the weakness and avoid it during the design.(3) Improved the weakness of MGB oil loss capability. The fist time using the powder metallurgic material on sliding friction subassembly of helicopter MGB. It proven that the material can improve the subassembly oil loss capability by laboratory test and bench test. And finally make sure the MGB oil loss test successful.