Abstract: Capacitive chip detectors for detecting metallic chips in engine fluid of an engine are provided. A capacitive chip detector includes a capacitor having first and second electric conductors. The detector further includes an inlet for receiving engine fluid between the first and second electric conductors. The capacitive chip detector includes an electric circuit including the capacitor, which capacitance changes when metallic chips are present between the first and second electric conductors. The electric circuit provides an output indicative of a chip detection between the first and second electric conductors.

Abstract: A method of operating a gas turbine engine having a bleed air system with a switching valve, operable to switch between multiple air sources depending on an operating mode of the gas turbine engine (e.g. a motive powered mode or a standby mode), is described. The method includes operating the switching valve to provide pressurized air from a selected one or more of the multiple air sources to a cavity of the gas turbine engine having seals, and testing the switching valve to determine if the switching valve is functioning normally or abnormally. The switching valve is functioning normally when operable to switch between the multiple air sources and is functioning abnormally when switching between the multiple air sources is not possible. If the switching valve is determined to be functioning abnormally, the gas turbine engine is controlled to prevent a change of the operating mode.

Abstract: A method of operating a gas turbine engine having a bleed air system with a switching valve, operable to switch between multiple air sources depending on an operating mode of the gas turbine engine (e.g. a motive powered mode or a standby mode), is described. The method includes operating the switching valve to provide pressurized air from a selected one or more of the multiple air sources to a cavity of the gas turbine engine having seals, and testing the switching valve to determine if the switching valve is functioning normally or abnormally. The switching valve is functioning normally when operable to switch between the multiple air sources and is functioning abnormally when switching between the multiple air sources is not possible. If the switching valve is determined to be functioning abnormally, the gas turbine engine is controlled to prevent a change of the operating mode.