Automatic turbine engine bleed valve control for enhanced fuel management

A gas turbine engine bleed air control system for controlling the compressor bleed valve position of an aircraft gas turbine engine having a compressor from which a portion of the air can be bled off, comprising:

• a normal bleed schedule;
• a fuel savings mode schedule;
• means for providing a gas generator speed signal indicative of gas generator speed;
• means for providing an altitude signal indicative of aircraft altitude;
• means for providing an air speed signal indicative of aircraft air speed;
• means responsive to the magnitude of said gas generator speed signal, said altitude signal and said air speed signal being greater than respective threshold magnitudes and the rate of change thereof being below respective threshold magnitudes for providing an enable signal;
• and
• said bleed air control system replacing said normal bleed schedule with said fuel savings mode schedule in response to said enable signal.

A method of controlling the position of a gas turbine engine compressor bleed valve in accordance with position schedules responsive to engine operating parameters, comprising the steps of:

• providing a normal bleed schedule;
• providing a fuel savings mode schedule;
• providing an enable signal, in response to the steady-state operation of said gas turbine engine above a threshold gas generator speed;
• and
• replacing said normal bleed schedule with said fuel savings mode schedule in response to said enable signal.

A method for controlling the compressor bleed valve position of an aircraft gas turbine engine having a compressor from which a portion of the air can be bled off, the method comprising the steps of:

• providing a normal bleed schedule;
• providing a fuel savings mode schedule;
• providing a gas generator speed signal indicative of gas generator speed;
• providing an altitude signal indicative of aircraft altitude;
• providing an air speed signal indicative of aircraft air speed;
• providing an enable signal in response to the magnitude of said gas generator speed signal, said altitude signal and said air speed signal being greater than respective threshold magnitudes and the rate of change thereof being below respective threshold magnitudes;
• and
• replacing said normal bleed schedule with said fuel savings mode schedule in response to said enable signal.