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 comprising a first spool and a second spool different from the first spool. A first parameter indicative of one of power of the first spool and a load transfer through a shaft of the second spool is obtained and a second parameter indicative of the other one of power of the first spool and the load transfer through the shaft of the second spool is obtained. A detection threshold is determined as a function of the first parameter. The second parameter is compared to the detection threshold. The shaft event is detected when the second parameter is beyond the detection threshold and then a signal indicative of the shaft event is transmitted.

A portable jig and fixture having at least one base plate, a column assembly removably coupled to the at least one base plate, a slide assembly removably coupled to the column assembly, a power feed head removably coupled to the slide assembly, and a spindle unit removably coupled with the slide assembly having a motor removably engaged it. At least one cutter assembly is removably engaged with the spindle unit and at least one drill jig is also removably engaged with the spindle unit. Also, a turbomachine having complementary structure on the compressor discharge casing can engage with the at least one base plate alignment mounting structure on the portable jig and fixture.

A portable jig and fixture having at least one base plate, a column assembly removably coupled to the at least one base plate, a slide assembly removably coupled to the column assembly, a power feed head removably coupled to the slide assembly, and a spindle unit removably coupled with the slide assembly having a motor removably engaged it. At least one cutter assembly is removably engaged with the spindle unit and at least one drill jig is also removably engaged with the spindle unit. Also, a turbomachine having complementary structure on the compressor discharge casing can engage with the at least one base plate alignment mounting structure on the portable jig and fixture.

Methods and systems of operating a gas turbine engine in a low-power condition are provided. In one embodiment, the method includes supplying fuel to a combustor by supplying fuel to a first fuel manifolds and a second fuel manifold of the gas turbine engine. The method also includes, while supplying fuel to the combustor by supplying fuel to the first fuel manifold: stopping supplying fuel to the second fuel manifold; and using a pump to drive gas into the second fuel manifold to flush fuel in the second fuel manifold into the combustor and hinder coking in the second fuel manifold and associated fuel nozzles.

A bowed rotor prevention system for a gas turbine engine includes a core turning motor operable to drive rotation of an engine core of the gas turbine engine. The bowed rotor prevention system also includes a full authority digital engine control (FADEC) that controls operation of the gas turbine engine in a full-power mode and controls operation of the core turning motor to drive rotation of the engine core using a reduced power draw when the FADEC is partially depowered in a low-power bowed rotor prevention mode.

A bowed rotor prevention system for a gas turbine engine includes a core turning motor operable to drive rotation of an engine core of the gas turbine engine. The bowed rotor prevention system also includes a full authority digital engine control (FADEC) that controls operation of the gas turbine engine in a full-power mode and controls operation of the core turning motor to drive rotation of the engine core using a reduced power draw when the FADEC is partially depowered in a low-power bowed rotor prevention mode.

A system and method for rotor bow mitigation for a gas turbine engine are provided. An elapsed time since a shutdown of the engine and an idle operation time of the engine prior to the shutdown are determined. A rotor bow mitigation period is determined based on the elapsed time and the idle operation time and, prior to initiating a start sequence of the engine, the engine is motored for a duration of the rotor bow mitigation period.

A system and method for rotor bow mitigation for a gas turbine engine are provided. An elapsed time since a shutdown of the engine and an idle operation time of the engine prior to the shutdown are determined. A rotor bow mitigation period is determined based on the elapsed time and the idle operation time and, prior to initiating a start sequence of the engine, the engine is motored for a duration of the rotor bow mitigation period.

A method is provided of controlling a gas turbine having a shaft connecting a compressor to a turbine, as well as having a reheat system, and a gas turbine. The method includes the steps of: operating the engine using the reheat system to provide a mass flow rate of reheat fuel into a gas flow of the gas turbine engine downstream of an exit of the turbine; detecting a shaft break event in the shaft; and in response to this detection, maintaining the mass flow rate of the reheat fuel being provided into the gas flow downstream of the turbine exit, whereby the maintained mass flow rate of reheat fuel raises a back pressure downstream of the turbine and thereby reduces a rotational speed of the turbine.

A method of controlling a gas turbine engine includes the steps of: detecting a shaft break event in a shaft connecting a compressor of the gas turbine engine to a turbine of the gas turbine engine; and in response to this detection, activating a shaft break mitigation system which introduces a fluid into a gas flow of the gas turbine engine downstream of the turbine, or increases an amount of a fluid being provided into the gas flow of the gas turbine engine downstream of the turbine, whereby the fluid reduces an effective area of a nozzle for the gas flow so as to reduce the mass flow rate of the gas flow through the turbine.