Overspeed protection for a turbocompressor of an aircraft powerplant assembly

A powerplant assembly for an aircraft, the powerplant assembly comprising:

• a propulsor rotor;
• an engine including an air intake, an engine exhaust, and an engine shaft, the engine shaft coupled with the propulsor rotor;
• a turbocompressor including a compressor section, a turbine section, and a rotational assembly, the rotational assembly including a bladed compressor rotor of the compressor section and a turbine rotor of the turbine section, the rotational assembly coupled with the propulsor rotor;
• the engine and the turbocompressor forming a gas flow path of the powerplant assembly, the gas flow path extending from the compressor section to the air intake, through the engine, and from the engine exhaust to the turbine section;
• and
• an overspeed protection valve forming a portion of the gas flow path, the overspeed protection valve positionable in an open state and a closed state, the overspeed protection valve in the open state operable to direct a gas flow along the gas flow path, the overspeed protection valve in the closed state operable to obstruct the gas flow along the gas flow path to the turbine section, the overspeed protection valve operable to sense a gas pressure along the gas flow path and change position from the open state to the closed state when the gas pressure decreases to a closing pressure setting of the overspeed protection valve.

A method for preventing an overspeed condition of a bladed turbine rotor of a turbocompressor of a powerplant assembly for an aircraft, the method comprising:

• driving rotation of a propulsor rotor with an engine shaft of an engine, the engine shaft coupled with the propulsor rotor;
• directing compressed air from a compressor section of the turbocompressor to the engine along a gas flow path;
• directing combustion exhaust gas from the engine to a turbine section of the turbocompressor to drive rotation of a rotational assembly of the turbocompressor, the rotational assembly including the bladed turbine rotor at the turbine section and a bladed compressor rotor at the compressor section;
• and
• preventing an overspeed condition of the bladed turbine rotor by obstructing the gas flow path with an overspeed protection valve by changing a position of the overspeed protection valve from an open state to a closed state to in response to a decrease in gas pressure within the gas flow path between the compressor section and the turbine section.