Lubrication system and methods of lubricating a gearbox assembly

A turbine engine comprising:

• a fan section including a fan;
• a fan shaft coupled to the fan, the fan shaft configured to rotate the fan;
• a turbine section including a high pressure shaft and a low pressure shaft;
• a gearbox assembly mechanically coupled to the turbine section;
• and
• a lubrication system comprising:
• a reservoir configured to store a lubricant;
• a primary lubricant supply circuit, the primary lubricant supply circuit including a primary supply pump fluidly coupled to the reservoir and mechanically coupled to the high pressure shaft of the turbine section;
• an auxiliary lubricant supply circuit, the auxiliary lubricant supply circuit including an auxiliary supply pump fluidly coupled to the reservoir and mechanically coupled to the low pressure shaft of the turbine section via a clutch;
• and
• a sensor that monitors a lubricant pressure within the primary lubricant supply circuit;
• wherein, when the lubricant pressure within the primary lubricant supply circuit falls below a predetermined lubricant threshold, the clutch is activated to engage the auxiliary supply pump and the low pressure shaft of the turbine engine and is deactivated to disengage the auxiliary supply pump and the low pressure shaft.

A method of supplying lubricant to a gearbox assembly of a turbine engine comprising:

• powering on the turbine engine, such that the turbine engine enters a normal operation mode;
• activating a primary lubricant supply circuit of a lubrication system of the turbine engine;
• circulating, via a primary supply pump of the primary lubricant supply circuit, a lubricant from a reservoir positioned within the turbine engine through the primary lubricant supply circuit, such that the lubricant passes through the gearbox assembly and returns to the reservoir;
• shutting down the turbine engine, such that the turbine engine enters a windmilling operation mode and the primary lubricant supply circuit is deactivated;
• activating an auxiliary lubricant supply circuit of the lubrication system of the turbine engine, wherein activating the auxiliary lubricant supply circuit includes engaging an auxiliary supply pump and a shaft of the turbine engine with a clutch;
• circulating, via the auxiliary supply pump of the auxiliary lubricant supply circuit, the lubricant from the reservoir through the auxiliary lubricant supply circuit, such that the lubricant passes through the gearbox assembly and returns to the reservoir;
• and
• deactivating the auxiliary lubricant supply circuit when the turbine engine is powered on, wherein deactivating the auxiliary lubricant supply circuit includes disengaging the auxiliary supply pump and the shaft with the clutch.