A system is provided for alternating starter use during multi-engine motoring in an aircraft. The system includes a first engine starting system of a first engine. A first controller is in communication with a second controller that controls a second engine starting system of a second engine, the first controller being configured to intermittently direct power to the first engine starting system to alternately accelerate and decelerate the first engine during motoring with respect to the second engine.

A system is provided for alternating starter use during multi-engine motoring in an aircraft. The system includes a first engine starting system of a first engine. A first controller is in communication with a second controller that controls a second engine starting system of a second engine, the first controller being configured to intermittently direct power to the first engine starting system to alternately accelerate and decelerate the first engine during motoring with respect to the second engine.

A system for bleeding air from a core flow path of a gas turbine engine is disclosed. In various embodiments, the system includes a bleed valve having a bleed valve inlet configured to receive a bleed air from a first access point to the core flow path and a bleed valve outlet; and an air motor having a first air motor inlet configured to receive the bleed air from the bleed valve outlet and a first air motor outlet configured to exhaust the bleed air, the air motor configured to pump the bleed air from the core flow path of the gas turbine engine.

An air turbine starter for starting an engine includes a starter housing defining an inlet, an outlet, and a flow path extending between the inlet and the outlet. A turbine section is located within the starter housing and includes a turbine member having a central disk and a set of airfoils spaced circumferentially about the central disk, as well as a sealing structure located within the starter housing.

An air turbine starter for starting an engine includes a starter housing defining an inlet, an outlet, and a flow path extending between the inlet and the outlet. A turbine section is located within the starter housing and includes a turbine member having a central disk and a set of airfoils spaced circumferentially about the central disk, as well as a sealing structure located within the starter housing.

Methods and systems for operating an on-off valve coupled to a system for regulating a system parameter are described herein. The method comprises setting an upper limit on a duty cycle of a pulse width modulation (PWM) signal for controlling the valve, generating the PWM signal with the duty cycle less than or equal to the upper limit and applying the PWM signal to the valve, monitoring the system parameter as the PWM signal is applied, and increasing the upper limit on the duty cycle over time until the system parameter reaches a target.

A bowed rotor start mitigation system for a gas turbine engine of an aircraft is provided. The bowed rotor start mitigation system includes a motoring system and a controller coupled to the motoring system and an aircraft communication bus. The controller is configured to determine at least one inferred engine operating thermal parameter based on at least one aircraft-based parameter received on the aircraft communication bus, where the at least one inferred engine operating thermal parameter is based on data describing a history of the aircraft before an engine shutdown. The motoring system is controlled to drive rotation of a starting spool of the gas turbine engine below an engine idle speed based on determining that the at least one inferred engine operating thermal parameter is within a preselected range.

A bowed rotor start mitigation system for a gas turbine engine of an aircraft is provided. The bowed rotor start mitigation system includes a motoring system and a controller coupled to the motoring system and an aircraft communication bus. The controller is configured to determine at least one inferred engine operating thermal parameter based on at least one aircraft-based parameter received on the aircraft communication bus, where the at least one inferred engine operating thermal parameter is based on data describing a history of the aircraft before an engine shutdown. The motoring system is controlled to drive rotation of a starting spool of the gas turbine engine below an engine idle speed based on determining that the at least one inferred engine operating thermal parameter is within a preselected range.

An air turbine starter for starting an engine includes a starter housing defining an inlet, an outlet, and a flow path extending between the inlet and the outlet. A turbine section is located within the starter housing and includes a turbine member having a central disk and a set of airfoils spaced circumferentially about the central disk, as well as a sealing structure located within the starter housing.

An air turbine starter for starting an engine includes a starter housing defining an inlet, an outlet, and a flow path extending between the inlet and the outlet. A turbine section is located within the starter housing and includes a turbine member having a central disk and a set of airfoils spaced circumferentially about the central disk, as well as a sealing structure located within the starter housing.