曝光台 注意防骗
网曝天猫店富美金盛家居专营店坑蒙拐骗欺诈消费者
• cowl anti-ice
• thrust reversers
14th-Stage Bleed Air Schematic
Figure 19-3
14TH STAGE
DUCT
FAIL
CLOSED
OPEN
DUCT
FAIL
CLOSED
BLEED AIR
L ISOL R
14th
Stage
L Wing
A/I Valve
R Wing
A/I Valve
L SOV R SOV
R Cowl
A/Ice
ISOL
L Cowl
A/ice
L Wing Anti-Ice
R Wing Anti-Ice
14th
Stage
P604_19_002
BLEED AIR PANEL
L T/R
PDU
R T/R
PDU
PNEUMATIC SYSTEM
19-6 For Training Purposes Only
May 03
P I LOT T R A I N I N G GU I D E
Components and Operation
14th-Stage Bleed Air Manifold
The 14th-stage bleed air manifold is located in the aft equipment bay. The left engine
pressurizes the left manifold and the right engine pressurizes the right manifold. 14thstage
bleed air can only be supplied by an operating engine. Manifold check valves are
installed to prevent reverse flow of 14th-stage air to an operating engine.
14th-Stage Isolation Valve
The isolation valve is located in the aft equipment bay and separates the left and right
wing anti-ice crossover duct. Refer to Chapter 14 Ice and Rain Protection for a
detailed description.
Engine 14th-Stage Bleed Air Valves
The 14th-stage bleed air valves are located in the aft equipment bay and control the
supply of 14th-stage bleed air from the engines to the manifold. The 14th stage valves
are electrically controlled, pneumatically operated valves, which either fully open or
fully close. The bleed air valves are spring-loaded open when no 14th-stage bleed air
is available or when electrical control power is lost.
The valves are manually commanded open or closed by the L (R) 14TH STAGE
switch/lights, located on the BLEED AIR Panel. The valves are automatically
commanded closed when the associated ENG FIRE PUSH switch/light is pressed.
However, when bleed air is no longer available after engine N2 spool down, the valve
will reopen regardless of the ENG FIRE PUSH switch/light position.
Valve status is indicated by the respective switch/light CLOSED annunciation (see
Figure 19-3).
Bleed air temperatures and pressures from the engine compressor 14th-stage are
unregulated and therefore dependent on engine power settings. Temperatures and
pressures can reach 950°F (510°C) and 215 psi (1482 kPa) at full thrust.
PNEUMATIC SYSTEM
For Training Purposes Only
May 03
19-7
P I LOT T R A I N I N G GU I D E
Bleed Air Leak Detection System
Description
The bleed air leak detection system monitors the pneumatic ducting downstream of the
10th-stage and 14th-stage bleed air shutoff valves and wing anti-ice valves along the
fuselage, pylon and wing areas.
Bleed air leaks that occur between the engine and the engine bleed air shutoff valves
are detected by the engine and jet pipe/pylon overheat detection system. Refer to
Chapter 9 Fire Protection.
To detect bleed air leaks, the 10th-stage and 14th-stage bleed air leak detection system
uses sensing elements (loops) for bleed air ducting in the aft equipment bay, the
portion of the cowl anti-ice ducting which passes through the engine pylon, and for the
wing anti-ice ducting passing through the fuselage.
Thermal switches detect bleed air leaks in the leading edge portion of the wing anti-ice
ducting.
Bleed Air Leak Detection Sensing Elements and Thermal Switches
Figure 19-4
P604_19_004
Left
Fuselage
Element
Right Fuselage
Element
Right Wing
(Same as Left)
Inner Duct Rupture
Air Bleed Hole
Bleed Leak-detection Element
(typical)
Thermal Switch
(typical)
PNEUMATIC SYSTEM
19-8 For Training Purposes Only
May 03
P I LOT T R A I N I N G GU I D E
Components and Operation
Bleed Leak Detection
The bleed air ducts are constructed of stainless steel, insulated, and encased by a
protective outer cover. A series of holes are drilled at designated locations in the outer
cover and sensing elements are installed adjacent to these holes. If a bleed air duct leak
develops, these holes direct the escaping hot air toward the leak detection sensing
elements.
Sensing Elements
The bleed air leak detection sensing elements operate in a similar manner to the
sensing elements used in the engine fire detection system.
The 10th-stage manifold uses a dual-loop sensing system. On a dual-loop system, both
loops must detect a leak before a duct overheat warning is given.
The 14th-stage bleed air manifold and the center fuselage wing anti-icing ducts are
monitored by single-loop systems.
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