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A pump system for lubricating a bearing in a gear system of a gas turbine engine includes a main pump, an auxiliary pump, an auxiliary reservoir, a sump, and a valve system. The main pump is fluidically connected to the bearing through a main supply passage. The auxiliary pump is fluidically connect

A pump system for lubricating a bearing in a gear system of a gas turbine engine includes a main pump, an auxiliary pump, an auxiliary reservoir, a sump, and a valve system. The main pump is fluidically connected to the bearing through a main supply passage. The auxiliary pump is fluidically connected to the bearing through an auxiliary supply passage. The valve system transfers lubricating liquid from the main pump to the bearing under a first set of engine operating conditions. The valve system transfers lubricating liquid from the auxiliary reservoir to the sump and from the sump through the auxiliary pump to the bearing under a second set of engine operating conditions. The valve system transfers lubricating liquid from the auxiliary reservoir through the auxiliary pump, bypassing the sump, to the bearing under a third set of engine operating conditions.

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1. A pump system for lubricating a bearing in a gear system of a gas turbine engine, the pump system comprising: a main pump fluidically connected to the bearing through a main supply passage;an auxiliary pump fluidically connected to the bearing through an auxiliary supply passage;an auxiliary rese

1. A pump system for lubricating a bearing in a gear system of a gas turbine engine, the pump system comprising: a main pump fluidically connected to the bearing through a main supply passage;an auxiliary pump fluidically connected to the bearing through an auxiliary supply passage;an auxiliary reservoir;a sump; anda valve system that transfers lubricating liquid from the main pump to the bearing under a first set of engine operating conditions, transfers lubricating liquid from the auxiliary reservoir to the sump and then from the sump through the auxiliary pump to the bearing under a second set of engine operating conditions, and transfers lubricating liquid from the auxiliary reservoir through the auxiliary pump, bypassing the sump, to the bearing under a third set of engine operating conditions. 2. The pump system of claim 1, and further comprising: a sensor for sensing pressure in the main supply passage, wherein the first set of engine operating conditions comprises pressure in the main supply passage exceeding a threshold, and wherein the valve system is actuated when the pressure in the main supply passage sensed by the sensor exceeds the threshold. 3. The pump system of claim 1, and further comprising: a first sensor for sensing pressure in the main supply passage, wherein the second set of engine operating conditions comprises pressure in the main supply passage being below a threshold; anda second sensor for sensing another condition selected from the group consisting of: air pressure downstream of a high pressure compressor being below a threshold;fuel pressure downstream of a fuel pump being below a threshold;lubricating liquid pressure downstream of the auxiliary pump being below a threshold; andgravitational forces acting on the pump system being above a threshold,wherein the valve system is actuated when the pressure in the main supply passage sensed by the first sensor and the another condition sensed by the second sensor are past their respective thresholds. 4. The pump system of claim 1, and further comprising: a first sensor for sensing pressure in the main supply passage, wherein the third set of engine operating conditions comprises pressure in the main supply passage being below a threshold; anda second sensor for sensing another condition selected from the group consisting of: air pressure downstream of a high pressure compressor being above a threshold;fuel pressure downstream of a fuel pump being above a threshold;lubricating liquid pressure downstream of the auxiliary pump being above a threshold; andgravitational forces acting on the pump system being below a threshold,wherein the valve system is actuated when the pressure in the main supply passage sensed by the first sensor and the another condition sensed by the second sensor are past their respective thresholds. 5. The pump system of claim 1, wherein the auxiliary pump is driven by the gear system and wherein the gear system comprises a fan drive gear system connecting a fan shaft to a low pressure spool. 6. The pump system of claim 1, wherein the main supply passage does not pass from the main pump through the auxiliary reservoir to the bearing, allowing fluid from the main supply passage to intermingle with fluid in the auxiliary reservoir. 7. A lubrication system for lubricating a bearing in a fan drive gear system for a gas turbine engine, the system comprising: a main pump;an auxiliary pump;an auxiliary reservoir;a sump;a first shuttle valve switchable between a first position fluidically connecting the auxiliary reservoir to an inlet of the auxiliary pump and a second position fluidically connecting the sump to the inlet of the auxiliary pump;a first sensor for sensing an engine operating condition, wherein the first sensor is connected to the first shuttle valve, and wherein the first shuttle valve is actuated between the first and second positions based upon the sensed engine operating condition;a second shuttle valve switchable between a first position fluidically connecting an outlet of the main pump to a bearing and a second position fluidically connecting an outlet of the auxiliary pump to the bearing; anda second sensor for sensing fluid pressure between the main pump and the second shuttle valve, wherein the second sensor is connected to the second shuttle valve, and wherein the second shuttle valve is actuated between the first and second positions based upon the sensed fluid pressure. 8. The lubrication system of claim 7, wherein the second shuttle valve fluidically connects an outlet of the auxiliary pump to a main reservoir in the first position and fluidically connects an outlet of the main pump to the main reservoir in the second position. 9. The lubrication system of claim 7, wherein the first sensor comprises a buffer pressure reference sensor having a sensor connected to a component of the gas turbine engine via a sensor passage for sensing the engine operating condition, and wherein the engine operating condition comprises a pressure selected from the group consisting of air pressure downstream of a high pressure compressor, fuel pressure downstream of a fuel pump, and lubricating liquid pressure downstream of the auxiliary pump. 10. The lubrication system of claim 9, wherein the first sensor actuates the first shuttle valve to the first position when the pressure is above a threshold and actuates the first shuttle valve to the second position when the pressure is below the threshold. 11. The lubrication system of claim 7, and further comprising: a bearing compartment defining a bearing compartment cavity, wherein the sump is positioned at a bottom of the bearing compartment and wherein the bearing compartment cavity contains the auxiliary pump, the auxiliary reservoir, the first shuttle valve, and the fan drive gear system. 12. A method of pumping lubricating liquid in a gas turbine engine, the method comprising: sensing an engine operating condition;supplying lubricating liquid from an auxiliary reservoir to a sump and then from the sump to an auxiliary pump when the sensed engine operating condition has a first value in a first range; andsupplying lubricating liquid from the auxiliary reservoir to the auxiliary pump, bypassing the sump, when the sensed engine operating condition has a second value in a second range. 13. The method of claim 12, and further comprising: pumping lubricating liquid from the auxiliary pump to a bearing of a fan drive gear system. 14. The method of claim 13, and further comprising: driving the auxiliary pump via the fan drive gear system. 15. The method of claim 12, and further comprising: sensing pressure in a main supply passage;pumping lubricating liquid from the auxiliary pump to a bearing when pressure in the main supply passage is below a threshold; andpumping lubricating liquid from a main pump to the bearing through the main supply passage when pressure in the main supply passage is above the threshold. 16. The method of claim 15, and further comprising: pumping lubricating liquid from the auxiliary pump to a main reservoir, bypassing the auxiliary reservoir, and then from the main reservoir to the main pump when pressure in the main supply passage is above a threshold. 17. The method of claim 15, and further comprising: collecting a portion of the lubricating liquid from the bearing in the auxiliary reservoir, wherein that portion of lubricating liquid does not first pass to the sump; andcollecting a portion of the lubricating liquid from the bearing in the sump. 18. The method of claim 12, wherein the engine operating condition comprises gravity. 19. The method of claim 12, wherein the engine operating condition comprises fluid pressure, wherein the first range includes pressure below a threshold, and wherein the second range includes pressure above the threshold. 20. The method of claim 19, wherein the fluid pressure comprises a pressure selected from the group consisting of air pressure downstream of a high pressure compressor, fuel pressure downstream of a fuel pump, and lubricating liquid pressure downstream of the auxiliary pump.