(g)  
6J18, ENG START AIR CONT

 (h)  
6K19, IGN 2 ENG 1

 (i)  
6K22, IGN 2 ENG 4

 F. Put the Airplane Back to Its Usual Condition
 S 845-252
 (1)  
Remove the DO-NOT-CLOSE tags and close the circuit breakers opened in the "Prepare for System Test" procedure.

 (2)  
Remove electrical power if it is not necessary (AMM 24-22-00/201).

 S 845-253
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747-400
MAINTENANCE MANUAL

 TASK 26-16-00-735-257
 5. Airflow Test for the Forward Cargo Sampling Tube
 A. Do the following steps:
 S 975-049
 (1)  Use one of the steps that follow to pressurize the ejector at STA 1490, WL 104, and BL 0 so that the pressure is between 15 and 50 psig:
 (a)  
Use the APU to pressurize the ejector.

 (b)  
Use a ground air source or regulated dry plant air to pressurize the ejector.

 NOTE: Disconnect the 3/4 " bleed air hose that goes down to
____ the right sidewall from the ejector at STA 1490 in the forward area of the aft cargo compartment. Connect the regulated plant air to the bleed air inlet of the ejector with an applicable connector.
 S 975-051
 (2)  Use the hot wire anemometer and the adaptor and write the air velocity in zone 1 at each orifice in the forward compartment (3 locations).
 -
(STA 480, RBL 42.5) feet per minute

 -
(STA 480, LBL 44.0) feet per minute

 -
(STA 540, RBL 42.5) feet per minute

 -
(STA 540, LBL 44.0) feet per minute

 -
(STA 600, RBL 42.5) feet per minute

 -
(STA 600, LBL 44.0) feet per minute

 -
(STA 660, RBL 42.5) feet per minute

 -
(STA 660, LBL 44.0) feet per minute.

 S 735-052
 (3)  Make sure the air velocity values are more than 150 feet per minute at each orifice.
 NOTE: This step and the subsequent step make sure that each
____ sampling orifice in the zone does not have blockage. It also makes sure each sampling orifice has the correct dimension.
 S 735-053
 (4)  Make sure the maximum air velocity value in zone 1 is not more than 120 feet per minute more than the minimum air velocity value in zone 1.
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A
747-400 MAINTENANCE MANUAL
 S 975-055
 (5)  Use the hot wire anemometer and the adaptor and write the air velocity in zone 2 at each orifice in the forward compartment (3 locations).
 -
(STA 740, RBL 42.5) feet per minute

 -
(STA 740, LBL 44.0) feet per minute

 -
(STA 800, RBL 42.5) feet per minute

 -
(STA 800, LBL 44.0) feet per minute

 -
(STA 860, RBL 42.5) feet per minute

 -
(STA 860, LBL 44.0) feet per minute

 -
(STA 920, RBL 42.5) feet per minute

 -
(STA 920, LBL 44.0) feet per minute.

 S 735-056
 (6)  
Make sure the air velocity values are more than 150 feet per minute at each orifice.

 S 735-057

 (7)  
Make sure the maximum air velocity value in zone 2 is not more than 120 feet per minute more than the minimum air velocity value in zone 2.

 S 865-058

 (8)  
Release the pressure from the crossover duct or the alternative pressure source (AMM 36-00-00/201).

 NOTE: If you used an alternative air source, remove the air source.
____ Connect the hoses at STA 1490. Torque the 3/4" ejector bleed air inlet (428 to 472 in. lb.) and make a mark on it.
 TASK 26-16-00-735-258
 6. Airflow Test for the Aft Cargo Sampling Tube
 A. Do the following steps:
 S 865-060
　
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