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Aircraft subsystems essential for flight safety and airworthiness, including flight controls, environmental control system (ECS), anti-icing, electricity generation, and starting, require engine bleed and power extraction. Predictions of the resulting impacts on maximum altitude net thrust(>8%), range, and fuel burn, and quantification of turbofan performance sensitivities with compressor bleed, and with both high pressure(HP) rotor power extraction and low pressure(LP) rotor power extraction were obtained from simulation. These sensitivities indicated the judicious extraction options which would result in the least impact. The “No Bleed” system in Boeing 787 was a major step forward toward More Electric Aircraft (MEA) and analysis in this paper substantiates the claimed benefits.

In addition to designing fighter engines for stall-free idle to maximum power operation and stall recoverability, it is important to give proper emphasis to sub-idle operation for successful starting. This permits the pilot to confidently bring the engine on-line following an inadvertent flameout caused by either the airplane departing the flight envelope or by a fuel interrupt due to a malfunction. Thus reliable and fast airstart capability enhances flight safety especially of single engine airplanes. Flight testing, therefore, is substantially devoted to airstart evaluation. The paper first explains the influence of engine design features on airstarting, particularly the advantages of the low bypass ratio cycle F100-PW-229 (PW229) engine, which is an increased thrust derivative (IPE) of the highly successful F100-PW-220 engine. Enhancing airstarting capability of the PW229 using variable geometry features and digital control flexibility is discussed.