Method for checking bleed-off valve closing point

A method for checking a closing point for a bleed-off valve for a gas turbine engine, the method comprising:

• determining a modulation characteristic curve for the bleed-off valve, the modulation characteristic curve is a function of a bleed-off valve outlet pressure of the bleed-off valve and an engine speed of the gas turbine engine;
• operating the gas turbine engine and increasing an engine power of the gas turbine engine until the engine speed reaches a predetermined testing value;
• determining a bleed-off valve measured value of the bleed-off valve outlet pressure and a gas turbine engine measured value of the engine speed when the engine speed reaches the predetermined testing value;
• determining an extrapolated closing point value of the bleed-off valve outlet pressure based on the engine speed, the extrapolated closing point value corresponds to the bleed-off valve outlet pressure of the modulation characteristic curve at the gas turbine engine measured value of the engine speed;
• and
• checking the closing point for the bleed-off valve by comparing the bleed-off valve measured value to a predetermined tolerance range of the extrapolated closing point value the extrapolated closing point value.