Patent ID: 8726674

Claim:
A propulsion unit for an aircraft, the propulsion unit comprising: a gas turbine engine including: first and second spools, an accessory gearbox driven by the second spool, a propeller gearbox provided with a propeller gearbox lubricant pump, and an integral turbomachinery lubricant pump driven from the accessory gearbox; a propeller configured to be driven by the first spool through the propeller gearbox; and a restart conduit configured to supply fluid delivered from the propeller gearbox lubricant pump to the turbomachinery lubricant pump, wherein windmilling the propeller drives the propeller gearbox lubricant pump and the turbomachinery lubricant pump to drive the second spool through the accessory gearbox to enable restarting of the engine, and the turbomachinery lubricant pump is formed of a centrifugal impeller that is configured to operate as a pump when driven from the accessory gearbox, and to operate as a motor when supplied with lubricant under pressure from the propeller gearbox lubricant pump through the restart conduit.