The filtering system used on a double reduction fan drive utilizes a positive displacement pump that is driven by the intermediate shaft. The pump forces oil through the filter mounted on the outside of the gear case. The filter contains a 75 micron, acrylic fiber element that has a low-pressure drop. The filter housing has a built-in bypass valve to ensure oil flow with a clogged filter. After filtering, the oil is routed inside the gear case where it is distributed to the bearings and gears using a manifold system.