H18546
Sensing Lines and Drain Plug 511
21-11-0 Figure 301 May 15/68
Page 302
BOEING PROPRIETARY - Copyright . - Unpublished Work - See title page for details.
ENGINE BLEED AIR COMPRESSION CONTROL SYSTEM - ADJUSTMENT/TEST
Engine Bleed Air Compression Control System Test
A. General
(1)
Bleed air from the engine to the air condition system is automatically adjusted by the modulating and shutoff valve, the pressure regulator and the pack valve. The control system permits bleed air from the 13th stage to enter the manifold and supplement the airflow output of the 8th stage bleed.
(2)
A solenoid on the pack valve is energized by the A/C pack switch to open or close the pack valve when the engine bleed air distribution system is pressurized. After the valve is opened it modulates automatically to control flow of air to the air cycle system. The following tests provide an operational check of the pneumatic and air cycle systems with the pneumatic system pressurized. For testing the air cycle system without pressurizing the engine bleed air distribution system, refer to 21-51-0, Air Cycle System -Adjustment/Test. Refer to 36-11-0, Adjustment/Test for checking duct leakage.
(3)
The engine bleed air distribution system can be pressurized by a ground pneumatic cart, by the auxiliary power unit (APU) or by engines. The following tests assume that the system is being pressurized either by engine(s) or by APU.
(4)
The test with engines running confirms proper operation of all components in the bleed air compression control system and air cycle system while the test with APU leaves out much of bleed air compression control but checks air cycle system, dual bleed warning, and the pack valve.
(5)
The pressure curve shown in Fig. 502 is for a standard day but does show a typical pattern for all conditions. The curve should not be used as a reason for squawking the bleed air distribution or air cycle systems, but should be used as a comparison of test observations.
(6)
These tests, as written, describe the left bleed air compression control system. The right system is identical except engine 2 should be operated.
B. Bleed Air Compression Control System Test With Engine Running
(1) Test Bleed Air Compression Control System
(a)
Check that air conditioning systems turbofans oil level are not below the ADD line on dipsticks and that the ACM's oil level extend at least three fourths the distance to the top of their sight glasses.
(b)
Operate engine No. 1 (Ref Chapter 71, Power Plant).
(c)
On forward overhead panel place ISOLATION VALVE switch to CLOSE position, the GASPER FAN and BLEED AIR switch on OFF, the PACK switch on ON, and the APU bleed switch on OFF, and check that bleed air pressure indicator reads 0 +1.5 psi.
(d)
Move PACK switch to OFF.
(e)
With engine running at IDLE, place BLEED AIR switch to ON, allow pressure to stabilize, then check that the bleed air pressure indicator reads 11 +3 psi.
(f)
Slowly increase engine power to 1.5 EPR while observing pressure indicator. Check that pressure remains at 11 +3 psi initially as power is increased then rises smoothly to a final value not exceeding 43 psi.
(g)
Slowly decrease engine power to idle and check that pressure indication decreases smoothly to 11 +3 psi.
(h)
Position PACK switch to ON, and AIR TEMP selector to SUPPLY DUCT.
(i)
Hold temperature selector to manual COOL until air mix valve moves to full COLD then move selector to OFF.
(j)
Check that air is emerging from cabin air outlets.
(k)
Slowly increase engine power to 1.5 EPR while observing pressure indicator and check that pressure rises smoothly as power is increased, stabilizes, then again rises smoothly. See Fig. 501 for approximate pressure at which stabilization will occur.
NOTE: Pressure stabilizing then starting to rise again is an indication that system has gone on 8th-stage bleed. The pressure at which stabilization occurs will depend on ambient conditions. The air supply duct indicated pressure curve, Fig. 501, illustrates the pattern at which duct pressure changes with respect to engine speed for different ambient conditions. Although curve does depict specific pressure for a specific condition, the importance of the curve is to show pattern expected when engine bleed air compression control system is operating normally. 中國航空網 www.k6050.com 航空翻譯 www.aviation.cn 本文鏈接地址：737 AMM 飛機維護手冊 AIR CONDITIONING 空調(21)
