28-22-07
ALL ú ú 02 Page 608 ú Dec 20/94
A
757
MAINTENANCE MANUAL
S 796-040
(3)
To find the leak in the fuel manifold you must purge the fuel tanks and do the steps that follow (AMM 28-11-00/201).
(a)
Put the valves in the postions shown in Fig 603 for the applicable test (Test 1, 2, 3 or 4) where the pressure decreased more than 1.5 psi.
(b)
Pressurize the fuel feed manifold at the inlet line for the left engine.
(c)
Go into the applicable fuel tank to isolate the leak
(AMM 28-11-00/201).
(d)
Do a check of the applicable fuel shutoff valve or crossfeed valve as follows. 1) Make sure the placard "TOP" shows on the top of the
applicable valve.
2) Make sure the index arrows on the adapter shaft and the valve body align correctly (AMM 28-22-01/401 and AMM 28-22-02/401).
(e) If the valve(s) is(are) installed correctly do a leak check of the fuel feed lines and couplings between the left engine inlet and the applicable valve:
Test 1 Right Engine Inlet Line Bleed Valve Test 2 Left Main Tank Shutoff Valve Test 3 Crossfeed Valve Test 4 Right Main Tank Shutoff Valve
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.
(f)
If a coupling has a leak, disconnect the coupling, replace the O-rings, and then connect the coupling (AMM 28-22-07/401).
(g)
If a fuel line has a leak, or has damage, remove and install a new fuel line (AMM 28-22-07/401).
S 796-041
(4)
After you correct a leak you must do a fuel manifold leak check as follows (Fig 601, 603):
(a)
Put the valves in the positions shown in Fig 603, Test 1.
EFFECTIVITYùùùùùùùùùùùùùùùùùùùùùùùùùùùùùù. ú
28-22-07
ALL ú ú 02 Page 609 ú Dec 20/94
A
757
MAINTENANCE MANUAL
(b)
Pressurize the fuel feed manifold to 40 psi from the inlet fuel line for the left engine.
(c)
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 876-019
(1)
Open the two bleed valves on the pressure test equipment slowly and let the pressure in the lines bleed to zero.
S 416-020 中国航空网 www.aero.cn 航空翻译 www.aviation.cn 本文链接地址：757 AMM 飞机维护手册 燃油 CHAPTER 28 - FUEL 3(80)
