# US 12,214,899 B1 · Propeller restraint kits for turboprop aircraft > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 12,214,899 B1 - Document ID: US12214899B1 - Status: Granted - Kind: B1 - Application number: 18/490,996 - Filed: 2023-10-20 - Granted: 2025-02-04 - Earliest claimed: 2023-10-20 - Assignees: Textron Innovations Inc. - Applicants: Textron Aviation Inc. - Inventors: Russell Ray Schrock; Michael Earl Lee - Web page: https://patentgrep.com/patent/US12214899B1 ## CPC - B64D 47/00: Equipment not otherwise provided for - B64F 1/00: Ground or aircraft-carrier-deck installations - B64F 1/005: {Protective coverings for aircraft not in use} - B64D: EQUIPMENT FOR FITTING IN OR TO AIRCRAFT; FLIGHT SUITS; PARACHUTES; ARRANGEMENT OR MOUNTING OF POWER PLANTS OR PROPULSION TRANSMISSIONS IN AIRCRAFT - B64F: GROUND OR AIRCRAFT-CARRIER-DECK INSTALLATIONS SPECIALLY ADAPTED FOR USE IN CONNECTION WITH AIRCRAFT; DESIGNING, MANUFACTURING, ASSEMBLING, CLEANING, MAINTAINING OR REPAIRING AIRCRAFT, NOT OTHERWISE PROVIDED FOR; HANDLING, TRANSPORTING, TESTING OR INSPECTING AIRCRAFT COMPONENTS, NOT OTHERWISE PROVIDED FOR ## Abstract Propeller restraint kits for turboprop aircraft are provided which include at least one, and preferably a pair, of propeller restraint systems. Each propeller restraint system will preferably include an open-ended propeller restraint boot that may be formed of a flexible and durable fabric material which is sized and configured for placement over the tip of a propeller blade. A cowling attachment assembly is provided in the kit and is adapted to being attached to an aircraft cowling skin. A propeller boot tether strap of predetermined length interconnects the propeller restraint boot and the cowling attachment assembly. The cowling attachment assembly includes (i) a quick disconnect (QD) pin assembly connected to a terminal end of the propeller boot tether strap, and (ii) a pin receiver adapted to being positionally attached to an interior portion of the aircraft cowling skin. ## Claims ### Claim 1 A propeller restraint kit for turboprop aircraft comprising: an open-ended propeller restraint boot sized and configured for placement over a tip of a propeller blade; a cowling attachment assembly adapted to being attached to an aircraft cowling skin; and a propeller boot tether strap of predetermined length interconnecting the propeller restraint boot and the cowling attachment assembly, wherein the cowling attachment assembly includes: (i) a quick disconnect (QD) pin assembly connected to a terminal end of the propeller boot tether strap, and (ii) a pin receiver adapted to being positionally attached to an interior portion of the aircraft cowling skin, the pin receiver including a pin receiving cylinder which is adapted to being positioned relative to a hole in the aircraft cowling skin to receive the quick disconnect pin and thereby removably attach the QD pin assembly and the pin receiver. ### Claim 2 (depends on 1) The propeller restraint kit according to claim 1, wherein the pin receiver includes a mounting flange for attaching the pin receiver to the interior portion of the aircraft cowling skin. ### Claim 3 (depends on 1) The propeller restraint kit according to claim 1, wherein the mounting flange defines a series of apertures adapted to receiving a rivet to immovably attached the mounting flange to the interior portion of the aircraft cowling skin. ### Claim 4 (depends on 2) The propeller restraint kit according to claim 2, wherein the pin receiver comprises an annular boss extending outwardly from a facing surface of the mounting flange, the annular boss being sized and configured to be positioned within the hole of the aircraft cowling skin. ### Claim 5 (depends on 1) The propeller restraint kit according to claim 1, wherein the propeller restraint boot is formed of a flexible fabric material. ### Claim 6 (depends on 1) The propeller restraint kit according to claim 1, wherein the propeller restraint boot includes a grommeted drain hole. ### Claim 7 (depends on 1) The propeller restraint kit according to claim 1, wherein the QD pin assembly comprises a strap swivel connected to the terminal end of the propeller boot tether strap. ### Claim 8 (depends on 1) The propeller restraint kit according to claim 1, wherein the pin receiver further includes a plug member which is moveably positioned within the receiving cylinder to plug the receiving cylinder upon disconnection of the QD pin and the pin receiver. ### Claim 9 (depends on 8) The propeller restraint kit according to claim 8, wherein the plug member includes a plug head and a plug stem having a terminal end coaxially extending outwardly from the receiving cylinder, and a retaining pin attached to the terminal end of the plug stem. ### Claim 10 (depends on 9) The propeller restraint kit according to claim 9, wherein the pin receiver further includes a compression spring positioned within the receiving cylinder and operably exerting spring force on the plug member. ### Claim 11 (depends on 1) The propeller restraint kit according to claim 1, further comprising: an exhaust pipe boot which is sized and configured to being placed over an end of an aircraft engine exhaust pipe, and an exhaust pipe boot tether strap having one end connected to the exhaust pipe boot and an opposite end connected to an intermediate portion of the propeller boot tether strap. ### Claim 12 (depends on 1) The propeller restraint kit according to claim 1, wherein the propeller restraint tether strap includes a length adjuster to allow length adjustment of the propeller restraint tether strap. ### Claim 13 A propeller restraint kit for a turboprop aircraft comprising a pair of propeller restraint systems adapted to restraining propeller blades of a turboprop aircraft in an inverted V-shaped configuration, wherein each of the propeller restraint systems comprises: an open-ended propeller restraint boot sized and configured for placement over a tip of a propeller blade; a cowling attachment assembly adapted to being attached to an aircraft cowling skin; and a propeller boot tether strap of predetermined length interconnecting the propeller restraint boot and the cowling attachment assembly, wherein the cowling attachment assembly includes: (i) a quick disconnect (QD) pin assembly connected to a terminal end of the propeller boot tether strap, and (ii) a pin receiver adapted to being positionally attached to an interior portion of the aircraft cowling skin, the pin receiver including a pin receiving cylinder which is adapted to being positioned relative to a hole in the aircraft cowling skin to receive the quick disconnect pin and thereby removably attach the QD pin assembly and the pin receiver. ### Claim 14 (depends on 13) The propeller restraint kit according to claim 13, wherein the pin receiver includes a mounting flange for attaching the pin receiver to the interior portion of the aircraft cowling skin. ### Claim 15 (depends on 14) The propeller restraint kit according to claim 14, wherein the mounting flange defines a series of apertures adapted to receiving a rivet to immovably attached the mounting flange to the interior portion of the aircraft cowling skin. ### Claim 16 (depends on 13) The propeller restraint kit according to claim 13, wherein the pin receiver comprises an annular boss extending outwardly from a facing surface of the mounting flange, the annular boss being sized and configured to be positioned within the hole of the aircraft cowling skin. ### Claim 17 (depends on 13) The propeller restraint kit according to claim 13, wherein the pin receiver further includes a plug member which is moveably positioned within the receiving cylinder to plug the receiving cylinder upon disconnection of the QD pin and the pin receiver. ### Claim 18 (depends on 17) The propeller restraint kit according to claim 17, wherein the plug member includes a plug head and a plug stem having a terminal end coaxially extending outwardly from the receiving cylinder, and a retaining pin attached to the terminal end of the plug stem. ### Claim 19 (depends on 18) The propeller restraint kit according to claim 18, wherein the pin receiver further includes a compression spring positioned within the receiving cylinder and operably exerting spring force on the plug member. ### Claim 20 (depends on 13) The propeller restraint kit according to claim 13, wherein the propeller restraint boot is formed of a flexible fabric material. ### Claim 21 (depends on 13) The propeller restraint kit according to claim 13, wherein the propeller restraint boot includes a grommeted drain hole. ### Claim 22 (depends on 13) The propeller restraint kit according to claim 13, wherein the QD pin assembly comprises a strap swivel connected to the terminal end of the propeller boot tether strap. ### Claim 23 (depends on 13) The propeller restraint kit according to claim 13, further comprising: an exhaust pipe boot which is sized and configured to being placed over an end of an aircraft engine exhaust pipe, and an exhaust pipe boot tether having one end connected to the exhaust pipe boot and an opposite end connected to an intermediate portion of the propeller boot tether strap. ### Claim 24 (depends on 13) The propeller restraint kit according to claim 13, wherein the propeller restraint tether strap of at least one of the propeller restraint systems includes a length adjuster to allow length adjustment of the propeller restraint tether strap. ### Claim 25 A turboprop aircraft which comprises a pair of propeller restraint systems to restrain propellers of the aircraft in an inverted V-shaped configuration, wherein each of the propeller restraint systems comprises: an open-ended propeller restraint boot positioned over a tip of a propeller blade; a cowling attachment assembly positionally fixed to cowling skin of the aircraft; and a propeller boot tether strap of predetermined length interconnecting the propeller restraint boot and the cowling attachment assembly, wherein the cowling attachment assembly includes: (i) a quick disconnect (QD) pin assembly connected to a terminal end of the propeller boot tether strap, and (ii) a pin receiver attached to an interior portion of cowling skin of the aircraft, wherein the cowling skin of the aircraft defines a hole and wherein the pin receiver includes a pin receiving cylinder which is positioned relative to the hole in the aircraft cowling skin to receive the quick disconnect pin and thereby removably attach the QD pin assembly and the pin receiver. ### Claim 26 (depends on 25) The aircraft according to claim 25, wherein the pin receiver includes a mounting flange attached to the interior portion of the aircraft cowling skin. ### Claim 27 (depends on 26) The propeller restraint kit according to claim 26, wherein the mounting flange defines a series of apertures, and wherein the pin receiver is attached to the interior portion of the aircraft cowling skin by rivets through the aircraft cowling skin and the apertures of the mounting flange. ### Claim 28 (depends on 26) The propeller restraint kit according to claim 26, wherein the pin receiver comprises an annular boss extending outwardly from a facing surface of the mounting flange, the annular boss being sized and configured to be positioned within the hole of the aircraft cowling skin so that an exterior surface of the aircraft cowling skin.