A method for barring a rotor of a thermally loaded turbomachine includes stopping normal operation of the turbomachine; providing a barring device for rotating the rotor about a machine axis; coupling the barring device to the rotor; letting the rotor cool down during cool down of the rotor rotating the rotor by means of the barring device. A damage of the machine due to thermally induced buckling during the barring process is avoided by consecutively determining the force or torque applied to the rotor by the barring device for rotating the rotor and/or the circumferential speed of the rotor during barring. The rotation of the rotor is controlled by means of the barring device in dependence of the determined force or torque and/or circumferential speed in order to reduce a bending or imbalance of the rotor, which is due to a nonuniform temperature distribution on the rotor during cool down.

An apparatus and method for reducing a pressure differential across a turbine 19 of a gas turbine engine 10 during a shaft break event, comprises a pressure equalization apparatus 200, 300, 400, 500, 600, 700 configured to introduce a pressurised fluid into a core airflow A at a region directly downstream of the turbine 19 in the event of a shaft break to directly increase a local pressure at the downstream region 29 of the turbine 19 and thereby reduce the pressure differential across the turbine 19. The reduction in the pressure differential may result in a reduction in the acceleration of the turbine 19.

An apparatus and method for reducing a pressure differential across a turbine 19 of a gas turbine engine 10 during a shaft break event, comprises a pressure equalization apparatus 300, 400, 500, 600, 700 configured to introduce a pressurised fluid into a core airflow A at a region downstream of the turbine 19, wherein a rearward movement of the turbine 19 or a shaft 26 in a shaft break event directly actuates the pressure equalisation apparatus 300, 400, 500, 600, 700 to directly increase a local pressure at the downstream region 29 of the turbine 19 and thereby reduce the pressure differential across the turbine 19. The reduction in the pressure differential may result in a reduction in the acceleration of the turbine 19.

An apparatus and method for reducing a pressure differential across a turbine 19 of a gas turbine engine 10 during a shaft break event, comprises a pressure equalization apparatus 200 configured to introduce a pressurised fluid into a core airflow A at a region downstream of the turbine 19 in the event of a shaft break to directly increase a local pressure at the downstream region 29 of the turbine 19 and thereby reduce the pressure differential across the turbine 19. The pressure equalization apparatus comprises a sensor 216 configured to directly detect a shaft break event. The reduction in the pressure differential may result in a reduction in the acceleration of the turbine 19.

There is described herein methods and systems for detecting a shaft event, such as a shaft shear, a shaft decoupling, and/or a shaft failure in a gas turbine engine. The method comprises determining a detection threshold as a set of threshold values for a spool speed of a first spool of the engine and a load transfer through a shaft of a second spool of the engine different from the first spool, the set of threshold values varying throughout a flight envelope, the detection threshold defining, for each spool speed value, at least one load transfer value beyond which a shaft event is detected. Operation values of the spool speed and the load transfer are obtained during operation of the engine, and the operation values are compared to the detection threshold. The shaft event is detected when the operation values are below the detection threshold.

A core section and nacelle assembly of a gas turbine engine includes a compressor located at an engine central longitudinal axis, a core case enclosing the compressor, and a nacelle located radially outboard of the core case and defining a core compartment between the nacelle and the core case. One or more vent openings are located in the nacelle to circulate a cooling airflow through the core compartment, and one or more fans are positioned at the one or more vent openings to urge the cooling airflow through the one or more vent openings to cool the core compartment.

There is described a shaft shear event detection method. The method comprises storing in memory a shaft oscillation signature determined as a function of known characteristics of the shaft and associated with a shaft shear event; monitoring a rotational speed of the shaft; detecting from the rotational speed an oscillation wave superimposed on the rotational speed, the oscillation wave having a wave modulation frequency and a wave modulation amplitude; comparing the oscillation signature to the oscillation wave; and detecting the shaft shear event when the oscillation wave corresponds to the oscillation signature.

An optical based system and method for monitoring turbine engine blade deflection during engine operation. An optical camera is coupled the exterior of an engine inspection port, so that its field of view captures images of a rotating turbine blade, such as the blade tip. The camera's image capture or sampling rate matches blade rotation speed at the same rotational position, so that successive temporal images of one or more blades show relative movement of the blade tip within the image field of view. The captured successive images are directed to a blade deflection monitoring system (BDMS) controller. The controller correlates change in a blade's captured image position within the camera field of view between successive temporal images with blade deflection. The BDMS alarms or trips engine operation if the monitored blade deflection falls outside permissible operation parameters.

An optical based system and method for monitoring turbine engine blade deflection during engine operation. An optical camera is coupled the exterior of an engine inspection port, so that its field of view captures images of a rotating turbine blade, such as the blade tip. The camera's image capture or sampling rate matches blade rotation speed at the same rotational position, so that successive temporal images of one or more blades show relative movement of the blade tip within the image field of view. The captured successive images are directed to a blade deflection monitoring system (BDMS) controller. The controller correlates change in a blade's captured image position within the camera field of view between successive temporal images with blade deflection. The BDMS alarms or trips engine operation if the monitored blade deflection falls outside permissible operation parameters.

A turbojet engine includes a fan shaft driven by a turbine shaft via a device for reducing the speed of rotation. The engine includes an uncoupling device interposed between the reduction device and the turbine shaft. The uncoupling device is configured to uncouple the reduction device and the turbine shaft in response to the exceeding of a determined resistant torque exerted by the reduction device on the turbine shaft.