Hydraulic

787 No-Bleed Systems: Saving Fuel and enhancing operational efficiencies
by mike Sinnett, Director, 787 Systems

The Boeing 787 Dreamliner features a unique systems architecture that offers numerous advantages to operators. The new airplane’s use of electrical systems reduces fuel usage and increases operational efficiency.

the primary differentiating factor in the systems architecture ofthe 787 is its emphasis on electrical systems, which replace most of the pneumatic systems found on traditional com­ mercial airplanes. one of the advantages of the no­bleed electri­ cal systems architecture is the greater efficiency gained in terms of reduced fuel burn — the 787 systems architecture accounts for predicted fuel savings of about 3 percent. the 787 also offers operators operationalefficiencies due to the advantages of electrical systems compared to pneumatic systems in terms of weight and reduced lifecycle costs. this article explores the 787’s no­bleed systems architecture and explains how the airplane’s efficiencies are realized.

reasons Behind the Move to a More eleCtriC airplane
recent advances in technology have allowed boeing to incorporate a new no­bleed systemsarchitecture in the 787 that eliminates the traditional pneumatic system and bleed manifold and converts the power source of most functions formerly powered by bleed air to electric power (for example, the air­conditioning packs and wing anti­ ice systems). the no­bleed systems architecture offers operators a number of benefits, including:
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expanded range and reduced fuel consumptiondue to lower overall weight. reduced maintenance costs and improved reliability because the architecture uses fewer parts than previous systems.

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improved fuel consumption, due to a more efficient secondary power extraction, transfer, and usage. reduced maintenance costs, due to elimination of the maintenance­intensive bleed system. improved reliability due to the use of modern powerelectronics and fewer components in the engine installation.

the 787’s no­bleed systems architecture will allow the airplane’s engines to produce thrust more efficiently — all of the high­speed air pro­ duced by the engines goes to thrust. pneumatic systems that divert high­speed air from the engines rob conventional airplanes of some thrust and increase the engine’s fuel consumption. boeingbelieves that using electrical power is more efficient than engine­generated pneumatic power, and expects the new architecture to extract as much as 35 percent less power from the engines. conventional pneumatic systems generally develop more power than is needed in most conditions, causing excess energy to be dumped overboard.

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787 NO-BlEED SySTEmSaRChiTECTURE

Figure 1 The 787’s no-bleed systems architecture replaces the traditional pneumatic system and the bleed manifold with a high-power electrical system that, in addition to the traditional electrical system functions, supports a majority of the airplane functions that were traditionally performed via bleed air.

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Heat Exchanger Trans / Rectifier Starter Generator Ram Air Turbine Hydraulic Pump Motor Cowl Thermal Anti-Ice

ELECTRiCAL pOWER iS MORE EFFiCiENT THAN ENgiNE-gENERATED pNEuMATiC pOWER.

Electrical Hydraulic Pneumatics Fuel Ram Air

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COmPaRiSON OF BlEED aND NO–BlEED ENGiNE BUilDUP

Figure 2 A comparison of typical engine buildups of a no-bleed engine (left) and the traditional bleed engine.

the ducting used to pass the pressurized air around the airplane employs check valves and pre­coolers, and is itself made of titanium, which adds hundreds of pounds of weight to the airplane. the...