An apparatus and method is provided to start gas turbine engines at cold start. A gearbox is not mechanically coupled to any accessory or to the starter-generator. Rather, a controller is used to route power to a starter-generator to rotate the turbine mainshaft to start the gas turbine engine. The controller prevents power to an accessory drive motor, until the starter-generator creates a positive torque. When a positive torque is reached, excess power is routed to the accessory drive motor, typically a brushless direct current motor.