Method of controlling a combustor

A method of controlling a combustor of a gas turbine engine, the method comprising:

• supplying a total fuel quantity to the combustor dependent on a load of the gas turbine engine, the total fuel quantity is split into a pilot fuel quantity and a main fuel quantity via a scheduled pilot fuel split,
• the scheduled pilot fuel split is the percentage of the pilot fuel quantity to the total fuel quantity,
• monitoring combustion instability,
• detecting that a predetermined temperature of the combustor is exceeded and/or that a predetermined value of combustion instability is exceeded,
• applying a steady state active pilot split offset to the scheduled pilot fuel split to create a steady state pilot fuel split, the steady state active pilot split offset being adjusted automatically in response to the predetermined temperature of the combustor being exceeded and/or the predetermined value of combustion instability being exceeded,
• monitoring a condition of the gas turbine engine that influences an air/fuel ratio in the combustor,
• detecting that the condition of the gas turbine engine is indicative of a transient condition and that a threshold value of combustion instability is exceeded,
• disabling adjustment of the steady state active pilot split offset in response to detecting that the condition of the gas turbine engine is indicative of the transient condition and that the threshold value of combustion instability is exceeded, and
• applying a transient active pilot split offset to the steady state pilot fuel split while maintaining the total fuel quantity being supplied at any point in time, the transient active pilot split offset and the steady state active pilot split offset result in a total split offset, the total split offset being greater than the steady state active pilot split offset, and
• a rate of change of the transient active pilot split offset is faster than a rate of change of the steady state active pilot split offset.