Windmill engine starting system with fluid driven motor and pump

In an aircraft gas turbine engine having a fan, compressor, combustor, high pressure turbine joined to the compressor by a core shaft, and a low pressure turbine joined to the fan by a fan shaft, an engine starting system comprising:

• a fluid assist pump operatively joined to said fan shaft;
• a fluid assist motor operatively joined to said core shaft and said assist pump;
• means for selectively engaging said assist pump and motor so that windmilling of said fan during aircraft flight powers said pump to in-turn power said motor to accelerate said core shaft to a minimum speed for allowing restarting of said engine in flight;
• and
• a fluid accumulator operatively joined to said assist motor and assist pump for storing fluid under pressure from said assist pump;
• wherein said engaging means further include:
• a start valve disposed in fluid communication between said assist pump and assist motor;
• a reserve valve disposed in fluid communication between said accumulator and said start valve;
• a check valve disposed in fluid communication between said assist pump and said start and reserve valves;
• and
• a controller operatively joined to said start valve and reserve valve for selectively opening said start valve to power said assist motor and for selectively opening said reserve valve to power said assist motor.