LPC ROTOR SEE B
23
1.6 4 SEE C
NO. 1 BALL BEARING
FRONT LPC HUB 4
1.6
23 1ST-STAGE STATOR
FAN EXIT FAIRING (FAN) BLADE 1ST-STAGE
SEE D SEE E
A L-A0698
Low Pressure Compressor (LPC)
Figure 6 (Sheet 1)
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1.6-, 2ND-, 3RD-, AND 4TH-STAGE BLADES
INLET CONE (REAR) SEGMENT
INLET CONE FRONT SEGMENT
INLET CONE B
LPC ROTOR C
FAN EXIT FAIRING 1ST-STAGE (FAN) BLADE
DE
L-A0703
Low Pressure Compressor (LPC) Figure 6 (Sheet 2)
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////////////////////////A / PW4000 SERIES /747-400 / ENGINES/MAINTENANCE MANUAL ////////////////////////
(2)
The 1st-stage of the LPC rotor, referred to as the "fan", is larger in diameter than the other compressor stages, and produces two separate airstreams. The primary (inner) airstream passes through the engine gaspath, where it is compressed and employed in the generation of heated gases which provide propulsive force. The secondary (outer) airstream is compressed by the fan and ducted outside the engine which provides additional propulsive force.
(3)
The LPC rotor is driven by the LPT. Structural support for the rotor is provided by the No. 1 ball bearing which is mounted on the front LPC hub. The LPC (1.6-, 2nd-, and 3rd-stage) stator is attached to the inner fan exit case and the rotor (1st-, 1.6-, 2nd-, 3rd-, and 4th-stage) is supported through the intermediate case. Surrounding the forward half of the LPC stator is a fan exit fairing which acts as an aerodynamic splitter separating the primary (main gas generator) airstream from the secondary (fan discharge) airstream.
C.
LPC/LPT Coupling (Fig. 7)
(1)
The LPC/LPT coupling consists of those interface parts that attach and secure the front LPC hub of the LPC rotor to the LPT shaft. The main feature of the LPC/LPT coupling is a turbine shaft coupling which is splined to the front LPC hub at the forward end and is splined to the LPT shaft at the rear. The turbine shaft coupling is supported structurally through the No. 1.5 roller bearing to the intermediate case. Mounted on the coupling is a motional pickup wheel from which the low rotor speed (N1) is determined.
D.
Fan Case (Fig. 8)
(1)
The fan case assembly consists of three separate fan cases: the front fan case, the fan exit case and vane (including the 2.5 bleed valve and linkage), and the fan exit rear case. The purpose of the fan cases is to contain and direct the fan discharge airstream and to provide the structural link between the airframe and the core engine. The fan case assembly supports the inlet cowl and provides for containment of the fan blades. The fan exit case and vane assembly straightens the fan discharge airstream prior to the air entering the thrust reverser flow path. The fan exit rear case is integral to the intermediate case.
(2)
The 2.5 bleed valve assembly is attached to the fan exit inner case at the LPC exit. The purpose of the bleed valve is to ensure stable operation at low power levels, to increase stall margin during starting, and when required during other operating conditions.
E.
Intermediate Case (Fig. 9)
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