A labyrinth seal, has: rotating and static components rotatable relative to one another relative to a central axis, the rotating component securable to a shaft via a tight fit engagement at an engagement location on the rotating component, the static component securable to a housing; teeth protruding from one of the rotating and static components towards a seal land defined by the other one of the rotating and static components; and clearances between the teeth and the seal land, a first clearance of the clearances greater than a second clearance of the clearances, the first clearance located closer to the engagement location of the rotating component than the second clearance.

A labyrinth seal, has: rotating and static components rotatable relative to one another relative to a central axis, the rotating component securable to a shaft via a tight fit engagement at an engagement location on the rotating component, the static component securable to a housing; teeth protruding from one of the rotating and static components towards a seal land defined by the other one of the rotating and static components; and clearances between the teeth and the seal land, a first clearance of the clearances greater than a second clearance of the clearances, the first clearance located closer to the engagement location of the rotating component than the second clearance.

A gear reduction reduces a speed of a fan rotor relative to a speed of a fan drive turbine. A fan case surrounds the fan rotor. A core engine has a compressor section and includes a low pressure compressor. The fan rotor delivers air into a bypass duct defined between the fan case and the core engine. A rigid connection between the fan case and the core engine includes a plurality of aft connecting members rigidly connected to the fan case, and to the core engine. A plurality of fan exit guide vanes are rigidly connected to the fan case, with the fan exit guide vanes including structural fan exit guide vanes which are rigidly connected to the core engine, and non-structural fan exit guide vanes, and the non-structural fan exit guide vanes being provided with an acoustic feature to reduce noise.

A gear reduction reduces a speed of a fan rotor relative to a speed of a fan drive turbine. A fan case surrounds the fan rotor. A core engine has a compressor section and includes a low pressure compressor. The fan rotor delivers air into a bypass duct defined between the fan case and the core engine. A rigid connection between the fan case and the core engine includes a plurality of aft connecting members rigidly connected to the fan case, and to the core engine. A plurality of fan exit guide vanes are rigidly connected to the fan case, with the fan exit guide vanes including structural fan exit guide vanes which are rigidly connected to the core engine, and non-structural fan exit guide vanes, and the non-structural fan exit guide vanes being provided with an acoustic feature to reduce noise.

A containment system for a gas turbine engine includes an outer containment ring having a first projection that extends radially inward and an inner containment ring having at least a second projection that extends radially outward toward the outer containment ring. The second projection is offset and spaced apart from the first projection to define a chamber in a first state. The containment system includes a lattice defined within the chamber that spans the chamber, and the lattice is integrally formed with each of the outer containment ring and the inner containment ring. A density of the lattice varies in at least one of an axial direction and a radial direction. The second projection is configured to interlock with the first projection in a second state.

A containment system for a gas turbine engine includes an outer containment ring having a first projection that extends radially inward and an inner containment ring having at least a second projection that extends radially outward toward the outer containment ring. The second projection is offset and spaced apart from the first projection to define a chamber in a first state. The containment system includes a lattice defined within the chamber that spans the chamber, and the lattice is integrally formed with each of the outer containment ring and the inner containment ring. A density of the lattice varies in at least one of an axial direction and a radial direction. The second projection is configured to interlock with the first projection in a second state.

A pressure regulating valve assembly includes: a valve having an upstream side receiving an input flow and a downstream side providing an output flow, an actuator for opening and closing the valve, including partially opening the valve, and a regulator controlling the actuator to open, close or partially open the valve. The regulator includes a sense pressure port, wherein pressure at the port is maintained constant by the regulator. A chamber has a first entry orifice, a second entry orifice and an exit orifice. The first entry orifice is connected to the upstream side, the second entry orifice is connected to the downstream side, and the exit orifice is connected to the port. The exit orifice provides that the pressure at the exit orifice lies between the pressure at the first entry orifice and the pressure at the second entry orifice.

A pressure regulating valve assembly includes: a valve having an upstream side receiving an input flow and a downstream side providing an output flow, an actuator for opening and closing the valve, including partially opening the valve, and a regulator controlling the actuator to open, close or partially open the valve. The regulator includes a sense pressure port, wherein pressure at the port is maintained constant by the regulator. A chamber has a first entry orifice, a second entry orifice and an exit orifice. The first entry orifice is connected to the upstream side, the second entry orifice is connected to the downstream side, and the exit orifice is connected to the port. The exit orifice provides that the pressure at the exit orifice lies between the pressure at the first entry orifice and the pressure at the second entry orifice.

An unducted fan turbine engine comprising an engine core including a first airflow, and a nacelle circumscribing at least a portion of the engine core and having an exterior surface defining a second airflow. The nacelle further comprising an internal passage between the exterior surface and the engine core, the internal passage defining a third airflow. The unducted fan turbine engine further comprising a plurality of rotatable fan blades extending radially beyond the exterior surface of the nacelle, and a cowl door located in the nacelle.

An unducted fan turbine engine comprising an engine core including a first airflow, and a nacelle circumscribing at least a portion of the engine core and having an exterior surface defining a second airflow. The nacelle further comprising an internal passage between the exterior surface and the engine core, the internal passage defining a third airflow. The unducted fan turbine engine further comprising a plurality of rotatable fan blades extending radially beyond the exterior surface of the nacelle, and a cowl door located in the nacelle.