# US 2014/0191079 A1 · Disconnecting a Rotor > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 2014/0191079 A1 - Document ID: US20140191079A1 - Status: Published application - Kind: A1 - Application number: 13/733,952 - Filed: 2013-01-04 - Published: 2014-07-10 - Earliest claimed: 2013-01-04 - Assignees: Bell Helicopter Textron Inc. - Applicants: Bell Helicopter Textron Inc. - Inventors: Ryan T. Ehinger; David Sembritzky; Carlos A. Fenny; Gary A. Cope; Charles J. Kilmain - Web page: https://patentgrep.com/patent/US20140191079A1 ## CPC - B64C 27/006: {Safety devices} - B64C 27/12: Rotor drives - B64C 27/14: Direct drive between power plant and rotor hub - B64C 27/82: characterised by the provision of an auxiliary rotor or fluid-jet device for counter-balancing lifting rotor torque or changing direction of rotorcraft - B64D 35/04: characterised by the transmission driving a plurality of propellers or rotors - B64C: AEROPLANES; HELICOPTERS - B64D: EQUIPMENT FOR FITTING IN OR TO AIRCRAFT; FLIGHT SUITS; PARACHUTES; ARRANGEMENT OR MOUNTING OF POWER PLANTS OR PROPULSION TRANSMISSIONS IN AIRCRAFT ## Abstract According to one embodiment, a clutch may be coupled between a rotor system and a power train of a rotorcraft. The clutch may be operable to disengage the rotor system from the power train during operation of the power train. A clutch control system in communication with the clutch and include a rotorcraft condition sensor operable to sense an operating condition of the rotorcraft and a control unit operable to prevent the clutch from disengaging the rotor system from the power train if the operating condition of the rotorcraft fails to satisfy a predetermined criterion. ## Claims ### Claim 1 A rotorcraft, comprising: a body; a power train coupled to the body and comprising a power source and a drive shaft coupled to the power source; a main rotor system coupled to the power train, the main rotor system comprising at least one main rotor blade; a secondary rotor system coupled to the power train, the secondary rotor system comprising at least one secondary rotor blade; a clutch coupled between the secondary rotor system and the power train, the clutch operable to disengage the secondary rotor system from the power train during operation of the power train; and a clutch control system in communication with the clutch and comprising: a rotorcraft condition sensor operable to sense an operating condition of the rotorcraft; and a control unit operable to prevent the clutch from disengaging the secondary rotor system from the power train if the operating condition of the rotorcraft fails to satisfy a predetermined criterion. ### Claim 2 (depends on 1) The rotorcraft of claim 1, wherein the secondary rotor system is an anti-torque rotor system. ### Claim 3 (depends on 1) The rotorcraft of claim 1, wherein the secondary rotor system is a tail rotor system. ### Claim 4 (depends on 1) The rotorcraft of claim 1, wherein the rotorcraft condition sensor comprises a weight-on-gear sensor and the operating condition fails to satisfy the predetermined criterion if a landing gear coupled to the body is supporting less than a predetermined weight. ### Claim 5 (depends on 1) The rotorcraft of claim 1, wherein the rotorcraft condition sensor comprises a throttle position sensor and the operating condition fails to satisfy the predetermined criterion if a throttle position associated with the power train exceeds a predetermined threshold. ### Claim 6 (depends on 1) The rotorcraft of claim 1, wherein the rotorcraft condition sensor comprises a collective position sensor and the operating condition fails to satisfy the predetermined criterion if a collective position associated with the at least one main rotor blade exceeds a predetermined threshold. ### Claim 7 (depends on 1) The rotorcraft of claim 1, wherein the rotorcraft condition sensor comprises a clutch input speed sensor and the operating condition fails to satisfy the predetermined criterion if a rotating component coupled between the power train and the clutch rotates faster than a predetermined threshold. ### Claim 8 (depends on 1) The rotorcraft of claim 1, wherein the rotorcraft condition sensor is operable to sense whether the rotorcraft is operating in autorotation flight and the operating condition fails to satisfy the predetermined criterion if the rotorcraft is operating in autorotation flight. ### Claim 9 (depends on 1) The rotorcraft of claim 1, further comprising a pilot warning system operable to provide a pilot warning indicating that the secondary rotor system is disengaged. ### Claim 10 (depends on 9) The rotorcraft of claim 9, wherein the pilot warning system provides the pilot warning if the secondary rotor system is disengaged and the operating condition of the rotorcraft fails to satisfy the predetermined criterion. ### Claim 11 (depends on 1) The rotorcraft of claim 1, further comprising a pilot warning system operable to provide a pilot warning indicating that a proximity sensor has sensed an object near the secondary rotor system. ### Claim 12 (depends on 1) The rotorcraft of claim 1, the control unit further operable to reengage the secondary rotor system if the operating condition of the rotorcraft no longer satisfies the predetermined criterion. ### Claim 13 A method of controlling disengagement of a rotor system from a power train of a rotorcraft, comprising: sensing an operating condition of the rotorcraft; comparing the operating condition to a predetermined criterion; and preventing disengagement of the rotor system from the power train if the operating condition fails to satisfy the predetermined criterion. ### Claim 14 (depends on 13) The method of claim 13, wherein the rotor system is an anti-torque rotor system. ### Claim 15 (depends on 13) The method of claim 13, wherein the rotor system is a tail rotor system. ### Claim 16 (depends on 13) The method of claim 13, further comprising allowing disengagement of the rotor system from the power train if the operating condition satisfies the predetermined criterion ### Claim 17 (depends on 16) The method of claim 16, reengaging the rotor system if the operating condition of the rotorcraft no longer satisfies the predetermined criterion. ### Claim 18 (depends on 13) The method of claim 13, wherein the operating condition fails to satisfy the predetermined criterion if a landing gear of the rotorcraft is supporting less than a predetermined weight. ### Claim 19 (depends on 13) The method of claim 13, wherein the operating condition fails to satisfy the predetermined criterion if a throttle position associated with the power train exceeds a predetermined threshold. ### Claim 20 (depends on 13) The method of claim 13, wherein the operating condition fails to satisfy the predetermined criterion if a collective position associated with at least one main rotor blade of the rotorcraft exceeds a predetermined threshold. ### Claim 21 (depends on 13) The method of claim 13, wherein the operating condition fails to satisfy the predetermined criterion if a rotating component coupled between the power train and the clutch rotates faster than a predetermined threshold. ### Claim 22 (depends on 13) The method of claim 13, wherein the operating condition fails to satisfy the predetermined criterion if the rotorcraft is operating in autorotation flight. ### Claim 23 (depends on 13) The method of claim 13, further comprising providing a pilot warning indicating when the rotor system is disengaged. ### Claim 24 (depends on 13) The method of claim 13, providing a pilot warning indicating that a proximity sensor has sensed an object near the rotor system.