Plural engine power producing system

A method of operating a power producing system utilizing a primary gas turbine engine including a gas generator having an operatively associated primary drive shaft and a secondary gas turbine engine including a compressor, a combustor, a turbine, and a secondary drive shaft drivingly interconnecting the turbine and compressor comprising the step of:

• selectively mechanically coupling the primary drive shaft and the secondary drive shaft whereby the secondary gas turbine engine augments the power output of the primary gas turbine while minimizing fuel consumption.

A method of operating a power plant system including a primary gas turbine engine and a secondary gas turbine engine so as to achieve optimum power augmentation and also minimal fuel consumption at low power levels comprising the steps of:

• while operating the primary engine, selectively coupling the compressor of the secondary engine to the gas generator of the primary engine, the secondary engine being substantially smaller than the primary engine, the gas generator of the primary engine including a primary compressor, a primary combustor, and a primary turbine drivingly engaged with the primary compressor;
• operating the secondary engine to supplement the primary engine by driving the primary engine gas generator and thereby increasing the mass flow of air through the primary engine.

A method of operating a power plant system including a primary gas turbine engine and a secondary gas turbine engine including a compressor and a turbine rotatably mounted on a secondary drive shaft and having a substantially lower power rating than the primary engine so as to achieve optimum power augmentation and also minimal fuel consumption at low power levels comprising the steps of:

• providing an auxiliary power unit operable for generating electricity for operating components external of the power plant system;
• and providing accessory components for generating the primary engine and the secondary engine;
• with the primary engine unfired, simultaneously coupling the secondary drive shaft to both said auxiliary power unit and said accessory components for operation thereof.