Aircraft engine with lubricant system having windmilling configuration
An aircraft engine has: a low-pressure assembly having first components having first inlets and first scavenge outlets; a high-pressure spool having second components having second inlets and second scavenge outlets; a lubricant system having: a lubricant tank; a main pump and a scavenge pump operable to drive a flow of the lubricant; a secondary pump; and valves; the lubricant system having: a standard configuration in which the valves define a standard flow path extending from the lubricant tank to the first inlets and the second inlets via the main pump; and a windmilling configuration in which the valves define a windmilling flow path extending from the lubricant source to the first inlets via the secondary pump while bypassing the main pump, and from the first scavenge outlets to the lubricant source while bypassing the scavenge pump.
1 . An aircraft engine for a multi-engine aircraft, comprising:
a low-pressure assembly including a low-pressure turbine drivingly connected to a rotatable load, the low-pressure assembly having first components engaged by, and configured to assist rotation of, the low-pressure turbine and the rotatable load, the first components being susceptible to rotation by windmilling and having first inlets and first scavenge outlets;
a high-pressure spool rotating independently of the low-pressure assembly and including a high-pressure turbine drivingly connected to a compressor, the high-pressure spool having second components engaged by, and configured to assist rotation of, the high pressure turbine and the compressor, the second components having second inlets and second scavenge outlets;
a lubricant system operatively connected to the first components and the second components, the lubricant system having:
a lubricant tank containing a volume of lubricant;
a main pump and a scavenge pump operable to drive a flow of the lubricant from the lubricant tank to the first inlets and the second inlets and from the first scavenge outlets and the second scavenge outlets back to the lubricant tank;
a secondary pump; and
valves selectively fluidly connecting or disconnecting the first inlets of the first components to the main pump or to the secondary pump and the first scavenge outlets to the scavenge pump or to a lubricant source;
the lubricant system having:
a standard configuration in which the valves are configured to define a standard flow path extending from the lubricant tank to the first inlets and the second inlets via the main pump while bypassing the secondary pump, and from the first scavenge outlets and the second scavenge outlets to the lubricant tank via the scavenge pump; and
a windmilling configuration in which the valves are configured to define a windmilling flow path extending from the lubricant source to the first inlets via the secondary pump while bypassing the main pump, and from the first scavenge outlets to the lubricant source while bypassing the scavenge pump.
2 . The aircraft engine of claim 1 , comprising a secondary scavenge pump, the windmilling flow path extending to the lubricant tank via the secondary scavenge pump.
3 . The aircraft engine of claim 2 , wherein the lubricant source is the lubricant tank.
4 . The aircraft engine of claim 2 , wherein the lubricant source includes a secondary lubricant tank, the secondary lubricant tank having an outlet fluidly connected to the secondary pump, the windmilling flow path extending through the secondary lubricant tank.
5 . The aircraft engine of claim 4 , wherein the lubricant system is devoid of a secondary scavenge pump between the first scavenge outlets and the secondary lubricant tank.
6 . The aircraft engine of claim 4 , wherein the secondary lubricant tank includes a vent fluidly connected to an environment outside the aircraft engine.
7 . The aircraft engine of claim 2 , wherein the secondary scavenge pump is driven by the low-pressure turbine.
8 . The aircraft engine of claim 1 , further comprising a controller operatively connected to the valves, the controller having a processing unit and a computer-readable medium having instructions stored thereon executable by the processing unit to:
determine that the aircraft engine is powered off and susceptible to windmilling while the multi-engine aircraft is flying; and
cause the valves to close the standard flow path and open the windmilling flow path.
9 . The aircraft engine of claim 8 , wherein the secondary pump is electrically driven, the computer-readable medium having the instructions stored thereon executable by the processing unit to:
power the secondary pump upon determining that the aircraft engine is power off and susceptible to windmilling while the multi-engine aircraft is flying.
10 . The aircraft engine of claim 1 , wherein the valves includes a first three-way valve disposed downstream of the main pump and upstream of the first components, and a second three-way valve disposed downstream of the first components and upstream of the scavenge pump.
11 . The aircraft engine of claim 1 , wherein the aircraft engine is a turboprop engine, the rotatable load being a propeller.