Abstract: A blade assembly including: a hub which is rotatable about an axis; at least one blade having an aerofoil portion and a root, wherein the root is coupled to the hub using a primary retention device which prevents radial separation of the root and hub in normal use; and, a secondary retention device having a root part and a hub part, the root part being located radially inwards of the hub part in a retention cavity in use, wherein at least a portion of the root part enters the retention cavity via an interlock which prevents radial separation of the root and hub in the event of a primary retention device failure.

Abstract: A propfan engine has a power-producing core, a plurality of nozzles for exhausting exhaust gas from the core, and a row of propeller blades rotatable about an axis. The blades are positioned downstream of the exhaust nozzles. The exhaust nozzles are rotatable about said axis. The nozzles can be aligned with the gaps between successive propeller blades in order to reduce noise during operation of the engine.

Abstract: A blade assembly including: a hub which is rotatable about an axis; at least one blade having an aerofoil portion and a root, wherein the root is coupled to the hub using a primary retention device which prevents radial separation of the root and hub in normal use; and, a secondary retention device having a root part and a hub part, the root part being located radially inwards of the hub part in a retention cavity in use, wherein at least a portion of the root part enters the retention cavity via an interlock which prevents radial separation of the root and hub in the event of a primary retention device failure.

Abstract: A gas turbine engine includes, in flow series, a generator section and a free power turbine. The generator section includes one or more generator turbine stages. One or more respective generator drive shafts extend axially forwardly from the generator turbine stages to one or more corresponding compressor stages. The free power turbine includes a first turbine stage and a contra-rotating second turbine stage. The gas turbine engine further includes a first drive shaft extending axially from the free power turbine to transmit rotational drive from the first turbine stage to a first propeller. The gas turbine engine further includes a second drive shaft extending from the free power turbine coaxially with the first drive shaft to transmit contra-rotational drive from the second turbine stage to a contra-rotating second propeller.

Abstract: A propfan engine has a power-producing core, a plurality of nozzles for exhausting exhaust gas from the core, and a row of propeller blades rotatable about an axis. The blades are positioned downstream of the exhaust nozzles. The exhaust nozzles are rotatable about said axis. The nozzles can be aligned with the gaps between successive propeller blades in order to reduce noise during operation of the engine.