(2) Close the thrust reverser doors (Ref. TASK 78-36-00-410-040): FOR 1000EM1 451AL, 452AR FOR 1000EM2 461AL, 462AR

 Subtask 75-22-10-440-051
 C. Make the thrust reverser serviceable (Ref. TASK 78-30-00-081-041).
 Subtask 75-22-10-860-052
 D. On the overhead panel 20VU, push the ENG1(2) FIRE pushbutton switch.
 Lower the guard on the pushbutton switch. R
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 Subtask 75-22-10-710-051

 E. Do a minimum idle leak check (Ref. TASK 71-00-00-710-006) and make sure that on the CFDS no fault is shown for the LPTACC valve.
 5. Close-up
________
 Subtask 75-22-10-410-053
 A. Close Access
 (1) Close the fan cowl doors (Ref. TASK 71-13-00-410-040): FOR 1000EM1 437AL, 438AR FOR 1000EM2 447AL, 448AR

 (2) Remove the warning notice(s).

 (3) Remove the access platform(s).

R Subtask 75-22-10-865-056
R B. Remove the safety clip(s) and the tag(s) and close this(these) circuit R breaker(s):
R -------------------------------------------------------------------------------R PANEL DESIGNATION IDENT. LOCATION R -------------------------------------------------------------------------------R 49VU FUEL/LP VALVE/MOT1/ENG2 2QG A09 R 49VU FUEL/LP VALVE/MOT1/ENG1 1QG A08
R Subtask 75-22-10-862-051
R C. De-energize the aircraft electrical circuits (Ref. TASK 24-41-00-862-R 002).
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 ROTOR ACTIVE CLEARANCE CONTROL SYSTEM (RACC) - DESCRIPTION AND OPERATION
________________________________________________________________________
 1. General

_______ (Ref. Fig. 001) The engine Rotor Active Clearance (RAC) and Start Bleed (SB) control system uses High Pressure Compressor (HPC) air from stage 5 to control compressor clearance at altitude, and stage 9 HPC bleed air to unload the compressor during starts and accelerations. The function of the RAC system is to improve compressor efficiency during cruise and the function of the SB system is to improve stall margin during engine starting and acceleration.

 2. Description

___________ (Ref. Fig. 002) The RACSB is an open loop system. The RAC control system ducts 5th stage compressor bleed air to the HPC bore cavity. The 5th stage air causes the rotor to expand and reduces HPC clearances. The increased efficiency of the HPC results in lower fuel consumption. The SB function is used during engine starting and acceleration from low speed. During transients, the 9th stage bleed increases engine stall margin. On engine start, the RACSB valve moves to a 9th stage bleed position which unloads the HPC to improve engine acceleration. At steady speeds above idle, at low altitudes, the RACSB valve is in the no air position. At high altitudes, the RACSB valve bleeds 5th stage air to heat the HPC bore which tightens compressor clearances and improves compressor efficiency. When the engine is shut down, the valve extends to a failsafe no air position.

 3. RACSB Valve Description

_______________________ (Ref. Fig. 003) The RACSB valve has integrated dual butterfly valves driven by a single fuel powered actuator. Position feedback to the ECU is provided by a dual channel LVDT attached on the actuator. One butterfly valve controls the flow of 5th stage compressor bleed while the other butterfly valve controls the flow of the 9th stage compressor bleed. The 5th stage air is ducted to the compressor bore cavity while the 9th stage air is ducted to the LPT cavity. The main valve modes are defined in the table that follows:
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 RACSB Schematic
 Figure 001

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 RACSB System
 Figure 002

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 RACSB Valve
 Figure 003

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 E E Feb 01/98 E E ECES E ---------------------------------------------------------------------------| Actuator | Mode | 5th Stage | 9th Stage | | Stroke | | Butterfly | Butterfly | |-------------------------------------------------------------------------| | 0 percent | No Air | Closed | Closed | | Failsafe | | | | |-----------------|---------------|-------------------|-------------------| | 19 percent | Transient | Closed | Fully open | | | Bleed/ | | | | | Start Bleed | | | |-----------------|---------------|-------------------|-------------------| | 52.5 percent | No Air | Closed | Closed | |-----------------|---------------|-------------------|-------------------| | 52.5-100 | Rotor Active | Intermediate | Closed | | percent | Clearance | | | ---------------------------------------------------------------------------
　
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