According to an aspect, a bowed rotor sensor system for a gas turbine engine is provided. The bowed rotor sensor system includes a bowed rotor sensor operable to transmit a sensing field in an observation region and receive a signal indicative of a gap between an air seal and a blade tip within the gas turbine engine. The bowed rotor sensor system also includes a controller operable to monitor a plurality of gap data from the bowed rotor sensor indicative of the gap between the air seal and the blade tip of a plurality of blades passing through the observation region and determine a bowed rotor status of the gas turbine engine based on the gap data.

A method is provided for operating an aircraft system. During this method, an engine is operated using first fuel provided by a first fuel source. A fuel supply for the engine is switched between the first fuel source and a second fuel source, where the switching of the fuel supply includes shutting down the engine during aircraft flight. The engine is operated using second fuel provided by the second fuel source.

A system for automated management of in-flight restarting of engines of an aircraft includes controllers, each engine of the aircraft being managed by one of the controllers. A controller that detects an engine that has stopped: cuts off the energy supply of the engine and performs a windmill engine start. If at least one other engine has stopped, prioritization of engine restarting includes: collecting information concerning a state of health of each engine; determining from the information collected information representing a probability of restarting each stopped engine; determining a sequential order of restarting the stopped engines as a function of information representing the probability of restarting each stopped engine. Each stopped engine continues to be windmill started until selection of the engine in question in the sequential order of restarting the stopped engines. Thus, the operational status of the aircraft is improved as quickly as possible.

A system for automated management of in-flight restarting of engines of an aircraft includes controllers, each engine of the aircraft being managed by one of the controllers. A controller that detects an engine that has stopped: cuts off the energy supply of the engine and performs a windmill engine start. If at least one other engine has stopped, prioritization of engine restarting includes: collecting information concerning a state of health of each engine; determining from the information collected information representing a probability of restarting each stopped engine; determining a sequential order of restarting the stopped engines as a function of information representing the probability of restarting each stopped engine. Each stopped engine continues to be windmill started until selection of the engine in question in the sequential order of restarting the stopped engines. Thus, the operational status of the aircraft is improved as quickly as possible.

There is described a method and system for in-flight start of an engine. The method comprises rotating a propeller; generating electrical power at an electric generator embedded inside a propeller hub from rotation of the propeller; transmitting the electrical power from the electric generator to an engine starter mounted on a core of the engine via an electric power link; and driving the engine with the engine starter to a sufficient speed while providing fuel to a combustor to light the engine to achieve self-sustaining operation of the engine.

There is described a method and system for in-flight start of an engine. The method comprises rotating a propeller; generating electrical power at an electric generator embedded inside a propeller hub from rotation of the propeller; transmitting the electrical power from the electric generator to an engine starter mounted on a core of the engine via an electric power link; and driving the engine with the engine starter to a sufficient speed while providing fuel to a combustor to light the engine to achieve self-sustaining operation of the engine.

Examples described herein provide a computer-implemented method that includes monitoring a hybrid electric turbine engine of an aircraft, the hybrid electric turbine engine including a first electric machine associated with a high speed spool and a second electric machine associated with a low speed spool. The method further includes receiving an indication of a failed electric machine, the failed electric machine being an electric machine on another hybrid electric turbine engine of the aircraft. The method further includes, responsive to detecting the failed electric machine, distributing power from one or more of the first electric machine or the second electric machine to a spool associated with the failed electric machine.

Aircraft hydrogen fuel systems and methods and systems of starting such systems are described. The aircraft hydrogen fuel systems include a hydrogen burning main engine, a main tank configured to contain liquid hydrogen to be supplied to the main engine during a normal operation, and a starter tank configured to contain gaseous hydrogen to be used during a startup operation of the main engine. Methods and processes for starting and/or restarting such systems are described.

Aircraft hydrogen fuel systems and methods and systems of starting such systems are described. The aircraft hydrogen fuel systems include a hydrogen burning main engine, a main tank configured to contain liquid hydrogen to be supplied to the main engine during a normal operation, and a starter tank configured to contain gaseous hydrogen to be used during a startup operation of the main engine. Methods and processes for starting and/or restarting such systems are described.

Methods and systems for controlling a bleed-off valve of a gas turbine engine are described. The method comprises maintaining a first bleed-off valve associated with a first compressor of the gas turbine engine at least partially open upon detection of an unintended engine disturbance causing a drop in pressure of a combustion chamber of the engine; monitoring a rotor acceleration of the first compressor; and controlling closure of the first bleed-off valve when the rotor acceleration of the first compressor reaches a first threshold for a first duration.