Patent ID: 7681402

Claim:
A method of adjusting oil flow to a gas turbine engine comprising providing a gearbox driven by at least one engine shaft, an oil system comprising a pump drivingly connected to the gearbox, an oil tank connected to the pump via a supply pipe, a delivery pipe connecting the pump to the engine for delivery of oil thereto, and an anti-siphon pipe connected between the tank and the delivery pipe to provide an excess oil flow to the engine and an oil flow over a sight glass in the tank, the anti-siphon pipe including a variable flow valve for regulating the flow of oil passing therethrough, wherein the variable flow valve is operable via a drive means and the drive means is operated via an engine control system, the method further comprising the steps of: operating the gas turbine engine to drive the gear box and oil system, thereby supplying oil to the engine; and opening the valve to increase oil flow at low engine speeds to provide adequate oil flow over the sight glass to provide fire protection.