Air turbine starter with automated variable inlet vanes

A method of assembling an air turbine starter comprising:

• obtaining an inlet housing;
• inserting a turbine wheel into the inlet housing, such that the inlet housing at least partially surrounds the turbine wheel, the turbine wheel including a hub integrally attached to a turbine rotor shaft and a plurality of turbine blades extending radially outward from the hub;
• rotatably connecting a plurality of turbine vanes on to a nozzle, the plurality of turbine vanes extending radially outward from the nozzle;
• inserting the nozzle into the inlet housing and upstream from the turbine wheel, the inlet housing defining an inlet flowpath between the nozzle and the inlet housing, the inlet flowpath configured to direct air flow into the plurality of turbine blades;
• operably connecting a sync-ring to each of the plurality of turbine vanes, wherein the sync-ring in operation rotates each of the plurality of turbine vanes when the sync-ring moves, and
• operably connecting an actuator to the sync-ring, wherein the actuator in operation moves the sync-ring,
• electronically connecting a controller to the actuator, and
• electronically connecting a speed sensor to the controller, wherein the speed sensor in operation detects the angular velocity of the turbine rotor shaft,
• wherein the plurality of turbine vanes extend radially outward from the nozzle into the inlet flowpath towards the inlet housing and the plurality of turbine vanes are rotatable to adjust air flow through the inlet flowpath,
• wherein each of the plurality of turbine vanes can be rotated to any selected angle in between a fully closed angle and a fully open angle, the fully open angle being equal to zero degrees and the fully closed angle being equal to 90 degrees, and
• wherein the controller is configured to determine turbine blade airflow requirements of the air turbine starter to mitigate a bowed rotor condition of a gas turbine engine operably connected to the air turbine starter in response to an angular velocity of the gas turbine engine, an angular velocity of the turbine rotor shaft, and a pressure upstream of the air turbine starter, and
• wherein the controller is further configured to operate the actuator in response to the determined turbine blade airflow requirements of the air turbine starter to mitigate the bowed rotor condition.