28-22-15
ALL ú ú 01 Page 605 ú Mar 15/94
BOEING PROPRIETARY - Copyright (C) - Unpublished Work - See title page for details.
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A
737-300/400/500MAINTENANCE MANUAL
S 796-023
(4) Make sure the pressure is 35 psi on the pressure gage for the right engine pressure check equipment.
NOTE: If the pressure at the right engine inlet is
____ 0 psi, one or more of these valves/actuators is closed and must be replaced.
Left Engine Shutoff Valve/Actuator Crossfeed Valve/Actuator Right Engine Shutoff Valve/Actuator
S 796-025
(5) Close the shutoff valve on the pressure check equipment for the left engine (Fig. 602).
(a)
Make sure the pressure at the left engine inlet does not decrease more than 1.5 psi in 10 minutes.
(b)
If the pressure does not decrease more than 1.5 psi in 10 minutes the system is OK. 1) Do this procedure: Put the Airplane Back to Its Usual
Condition.
(c)
If the pressure decreases more than 1.5 psi in 10 minutes, there is a leak in the fuel feed manifold.
S 796-026
(6) To find the general location of the leak in the fuel manifold, do these steps:
(a)
Close the right engine fuel shutoff valve (spar valve) and do the test again.
(b)
If the pressure does not decrease by more than 1.5 psi in 10 minutes, the leak is between the right engine fuel shutoff valve and the right engine.
(c)
If the pressure decreases by more than 1.5 psi in 10 minutes, close the crossfeed valve and do the test again.
(d)
If the pressure does not decrease by more than 1.5 psi in 10 minutes, the leak is between the crossfeed valve and the right engine fuel shutoff valve.
(e)
If the pressure decreases by more than 1.5 psi in 10 minutes, close the left engine fuel shutoff valve and do the test again.
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28-22-15
ALL ú ú 01 Page 606 ú Nov 15/94
BOEING PROPRIETARY - Copyright (C) - Unpublished Work - See title page for details.
A
737-300/400/500MAINTENANCE MANUAL
(f)
If the pressure does not decrease by more than 1.5 psi in ten minutes, the leak is between the crossfeed valve and the left engine fuel shutoff valve.
(g)
If the pressure decreases by more than 1.5 psi in ten minutes, the leak is between the left engine fuel shutoff valve and the left engine.
S 796-016
(7) After you find the general location of the leak, do the purging and entry procedure for the applicable fuel tank (AMM 28-10-00/201) and do these steps to find the exact location of the leak:
(a)
Pressurize the fuel feed manifold at the inlet line for the left engine.
(b)
Go into the applicable fuel tank to isolate the leak (AMM 28-10-00/201).
(c)
Do a leak check of the fuel feed lines and couplings in the area where the pressure test failed:
CAUTION: YOU CANNOT TIGHTEN THE FUEL LINE COUPLING AFTER THE
_______ INITIAL INSTALLATION. YOU MUST INSTALL NEW O-RINGS WHEN YOU TIGHTEN THE FUEL LINE COUPLING AGAIN OR A FUEL LEAK CAN OCCUR.
(d)
If a coupling has a leak, disconnect the coupling, replace the O-rings, and then connect the coupling (AMM 28-22-15/401).
(e)
If a fuel line has a leak, or has damage, remove and install a new fuel line (AMM 28-22-15/401).
S 796-017
(8) After you repair a leak, do these steps:
(a)
Pressurize the fuel feed manifold to 35 psi from the inlet fuel line for the left engine.
(b)
If the pressure does not decrease by more than 1.5 psi in 10 minutes, the system is OK.
F. Put the Airplane Back to Its Usual Condition
S 876-018
(1)
Open the two bleed valves on the pressure test equipment slowly and let the pressure in the lines bleed to zero.
S 416-019
(2)
Install the access doors on the fuel tank(s)
(AMM 28-11-11/401, AMM 28-11-31/401).
S 086-020
(3)
Remove the pressure check equipment from the air pressure source and the inlet fuel feed lines.
(4)
Connect the left and right engine inlet fuel feed lines (Fig. 601).
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