# US 9,517,842 B2 · Filters for aircraft engine inlets > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 9,517,842 B2 - Document ID: US9517842B2 - Status: Granted - Kind: B2 - Application number: 14/292,248 - Filed: 2014-05-30 - Published: 2015-12-03 - Granted: 2016-12-13 - Earliest claimed: 2014-05-30 - Assignees: Bell Helicopter Textron Inc. - Applicants: Bell Helicopter Textron Inc. - Inventors: Albert G. Brand - Web page: https://patentgrep.com/patent/US9517842B2 ## CPC - B64D 33/02: of combustion air intakes - B64C 27/04: Helicopters - F02C 7/055: with intake grids, screens or guards - B64D 2033/0246: {comprising particle separators} - Y02T 50/60: Efficient propulsion technologies, e.g. for aircraft - B64D: EQUIPMENT FOR FITTING IN OR TO AIRCRAFT; FLIGHT SUITS; PARACHUTES; ARRANGEMENT OR MOUNTING OF POWER PLANTS OR PROPULSION TRANSMISSIONS IN AIRCRAFT - B64C: AEROPLANES; HELICOPTERS - F02C: GAS-TURBINE PLANTS; AIR INTAKES FOR JET-PROPULSION PLANTS; CONTROLLING FUEL SUPPLY IN AIR-BREATHING JET-PROPULSION PLANTS (construction of turbines F01D; jet-propulsion plants F02K; construction of compressors or fans F04; generating combustion products of high pressure or high velocity F23R; using gas turbines in compression refrigeration plants F25B11/00) - Y02T: CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO TRANSPORTATION ## Abstract Some examples of an aircraft engine barrier filtration system include an engine barrier filter layer positioned near an aircraft engine intake. The filter layer filters aircraft engine intake air. The system includes a check valve assembly positioned adjacent to the engine barrier filter layer. The check valve assembly permits the engine intake air to flow into the engine through the filter layer during a first aircraft operation mode and to prevent air flow away from the engine through the filter layer during a second aircraft operation mode that is different from the first aircraft operation mode. ## Claims ### Claim 1 An aircraft engine barrier filtration system comprising: an engine barrier filter layer positioned near an aircraft engine intake, the filter layer to filter aircraft engine intake air; and a passive one-way check valve assembly positioned adjacent to the engine barrier filter layer, the passive one-way check valve assembly to permit the engine intake air to flow into the engine in a first flow direction through the filter layer during a first aircraft operation mode and to substantially prevent air flow away from the engine in a second flow direction through the filter layer opposite the first flow direction during a second aircraft operation mode that is different from the first aircraft operation mode; wherein the check valve assembly comprises a system of reed valves; with: a first layer comprising a plurality of openings; and a second layer attached to the first layer, the second layer comprising a plurality of reeds, each reed aligned with a corresponding opening of the plurality of openings. ### Claim 2 (depends on 1) The system of claim 1, wherein the check valve assembly is positioned between the aircraft engine and the filter layer. ### Claim 3 (depends on 1) The system of claim 1, wherein the first aircraft operation mode is either a hover mode or an idling mode, or a flight mode with contaminated air, and wherein the second aircraft operation mode is a flight mode with clean air. ### Claim 4 (depends on 1) The system of claim 1, wherein the second layer is formed from a flexible material or a rigid material that is hinged. ### Claim 5 (depends on 1) The system of claim 1, wherein the plurality of openings and the plurality of reeds are rectangular. ### Claim 6 (depends on 1) The system of claim 1, wherein the filter layer is positioned between the aircraft engine and the check valve assembly with a spacer that permits the reed valves to open or close. ### Claim 7 (depends on 6) The system of claim 6, wherein the check valve assembly is arranged in corrugated layers that permit the reed valves to open or close. ### Claim 8 (depends on 1) The system of claim 1, wherein the check valve assembly covers less than an entirety of the filter layer. ### Claim 9 An aircraft engine barrier filtration and check valve system comprising: an engine barrier filter layer positioned near an aircraft engine intake, the filter layer to filter aircraft engine intake air; and a passive one-way check valve assembly attached to the engine barrier filter layer, the check valve assembly to either permit the engine intake air to flow into the engine through the filter or to substantially prevent air flow away from the engine through the filter based, in part, on an aircraft operation mode; wherein the check valve assembly comprises: a first layer comprising a plurality of openings; and a second layer attached to the first layer, the second layer comprising a plurality of reeds, each reed aligning with a corresponding opening of the plurality of openings. ### Claim 10 (depends on 9) The system of claim 9, wherein the check valve assembly is configured to permit the engine intake air to flow into the engine when the aircraft operation mode is either a hover mode or an idling mode that requires filtered air for the engine. ### Claim 11 (depends on 9) The system of claim 9, wherein the check valve assembly is configured to prevent air flow away from the engine when the aircraft operation mode is a flight mode that does not require filtered air for the engine. ### Claim 12 (depends on 11) The system of claim 11, wherein the aircraft operation mode is a mode in which the aircraft requires filtered air or a mode in which the aircraft does not require filtered air. ### Claim 13 (depends on 9) The system of claim 9, wherein the filter layer is positioned between the aircraft engine and the check valve assembly. ### Claim 14 (depends on 9) The system of claim 9, wherein the check valve assembly is positioned between the aircraft engine and the filter layer. ### Claim 15 A method of providing intake air to an aircraft engine, the method comprising: permitting flow of aircraft engine intake air in a first direction into an aircraft engine through a passive one-way check valve assembly and through an engine harrier filter layer during a first aircraft operation mode; and preventing, with the passive one-way check valve assembly, flow of air in a second, opposite direction away from the engine through the passive one-way check valve assembly and the engine barrier filter layer during a second aircraft operation mode that is different from the first aircraft operation mode wherein the passive one-way check valve assembly comprises a system of reed valves with: a second layer attached to the first laver, the second layer comprising plurality of reeds, each reed aligning with a corresponding opening of the plurality of openings. ### Claim 16 (depends on 15) The method of claim 15, wherein the first aircraft operation mode is either a hover mode or an idling mode, and wherein the second aircraft operation mode is a flight mode. ### Claim 17 (depends on 15) The method of claim 15, wherein the first aircraft operation mode is an operation mode in which the aircraft requires filtered air and the second aircraft operation mode is an operation mode in which the aircraft does not required filtered air. ### Claim 18 (depends on 15) The method of claim 15, wherein the one-way check valve is positioned adjacent to the engine barrier filter layer.