(i)  
Position LIGHTS switch on P2 panel to DIM and check that lights noted in step (g) dim.

(j)  
Position switch to BRT position and check that lights return to original brightness.

(k)  
Depress either MASTER CAUTION light and check that both MASTER CAUTION lights and the AIR COND annunciator light extinguish but the applicable BLEED TRIP OFF light on the P-5 panel remains illuminated.

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(l)  
Depress either MASTER CAUTION annunciator and check that both MASTER CAUTION lights and all MASTER CAUTION annunciator lights illuminate, but when released only the MASTER CAUTION lights, and AIR COND annunciator light on lightshield panel remain illuminated

(m)  
Allow sufficient time for thermal switch probe to cool. Push TRIP RESET button on control panel, and check that BLEED TRIP OFF annunciator and all MASTER CAUTION annunciator lights extinguish and bleed air valve opens.

(n)  
Reinstall bleed air overheat switch (4900F) on duct.

(o)  
Position ENGINE 1 FIRE switch on aft electronic panel (P8) to FIRE and check that bleed air shutoff valve closes.

(p)  
Reposition FIRE SWITCH to NORMAL. Check that bleed air shutoff valve opens.

(q)  
Position ENGINE 1 BLEED SWITCH to OFF and check that valve closes.

(r)  
Repeat test for engine 2.

(4)  Restore Airplane to Normal
(a)  
Remove electrical power if no longer required.

(b)  
Close right engine cowl.

C.  Bleed Air Isolation Valve Test
(1)  
Prepare to Test Bleed Air Isolation Valve

(a)  
Open air conditioning bay doors.

(b)  
Provide electrical power.

(c)  
Check that the following circuit breakers are closed (P6).
1) MASTER CAUTION (all except FUEL, if installed)
2) INDICATOR LTS, MASTER DIM BUS (9 places)
3) DIM & TEST (1 place)

(2)  
Test Bleed Air Isolation Valve

(a)  Position ISOLATION VALVE switch to AUTO and move pack switches and bleed switches to positions listed in the following table. Check that isolation valve moves to or stays in position noted.
PACK SWITCH POSITION BLEED SWITCH POSITION VALVE POSITION
L - R ON 1 - 2 ON CLOSED L OFF - R ON 1 - 2 ON OPEN L ON - R OFF 1 - 2 ON OPEN L - R ON 1 - 2 OFF OPEN L - R ON 1 - OFF - 2 ON OPEN L - R OFF 1 - 2 OFF OPEN
(b)  
Position L. PACK, R. PACK and both BLEED switches to OFF and ISOLATION VALVE switch to CLOSE and check that isolation valve closes.

(c)  
Position L. PACK, R. PACK and both BLEED SWITCHES to ON and ISOLATION VALVE switch to OPEN and check that isolation valve opens.

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(3)  Restore Airplane to Normal Configuration
(a)  
Remove electrical power if no longer required.

(b)  
Close air conditioning equipment bay doors.

D.  Bleed Air System Leakage Test -Time Pressure Drop Method
(1) 
 General

(a)  This task does not use any special equipment. The APU is used to supply pneumatic pressure to test whether the level of leakage from the bleed air system and precooler ducting are within acceptable limits.

(2)  
Prepare to Leak Test Bleed Air System

(a)  
Provide electrical power.

(b)  
Check that the following switches on the forward overhead panel are OFF: 1) WING ANTI-ICE 2) BLEED 1 3) BLEED 2 4) L PACK 5) R PACK 6) ENGINE START 1 7) ENGINE START 2

(c)  
Check that indicators on turbofan control valves are at CLOSE.

(3)  
Leak Test the Right Bleed Air System

(a)  
On the forward overhead panel, position the APU BLEED switch to ON.

(b)  
Check that the ISOLATION VALVE switch on the forward overhead panel is in the OPEN position.

(c)  
Position the BLEED 2 switch on the forward overhead panel to ON.

(d)  
Pressurize the pneumatic system with the APU.

(e)  
When the bleed air duct pressure is stable, record the right duct pressure shown on the forward overhead panel.

(f)  
Check that the right manifold is pressurized to a minimum of 20 psig.

(g)  
At the same time on the forward overhead panel, position the ISOLATION VALVE switch to CLOSE and the APU BLEED switch to OFF.
　
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