Air/oil separation system and method

A centrifugal air/oil separation system substantially positioned inside a rotatable hollow shaft of an engine disposed substantially horizontally the system comprising:

• an annular separating chamber defined co-axially within and radially spaced from the hollow shaft and adapted to rotate together with the hollow shaft;
• a stationary annular cavity positioned at an end of the hollow shaft, communicating with a cavity of the engine disposed outside a gearbox, for collecting an air/oil mixture therefrom such that the air/oil mixture is substantially isolated from contacting components inside the gearbox;
• a mixture inlet passage defined between the annular cavity and the annular separating chamber, permitting the air/oil mixture in the annular cavity to enter the annular separating chamber for centrifugal separation;
• an air outlet passage defined through the annular cavity, communicating the annular separating chamber for discharging air separated from the air/oil mixture in the annular separating chamber;
• and
• an oil outlet passage for discharging liquid oil separated from the air/oil mixture in the annular separating chamber into the annular cavity.