F95045
539 APU Fuel Line Shroud Drain System
Feb 01/76 Figure 2 28-13-0
Page 5
BOEING PROPRIETARY - Copyright . - Unpublished Work - See title page for details.
FUEL VENT SYSTEM - INSPECTION/CHECK
1. Fuel Vent System Pressure Check
A. General
(1)
The fuel vent system must be pressure checked after any maintenance which may have affected the system or after a fuel leak has been traced to the system.
(2)
The pressure check is accomplished by closing all fuel shutoff valves and blocking off the vent ram air scoops and internal vent openings including float valves, check valves, and vent line drain holes. Air pressure of 5.0 士0.2 psi is then applied to the system through a hose connection.
CAUTION: THE MAXIMUM INTERNAL PRESSURE TO WHICH THE VENT SYSTEM AND FUEL TANKS MAY BE SUBJECTED IS 5.20 PSI.
(3)
Ambient temperature and atmospheric pressure should be stable during system pressure checks.
B. Equipment and Materials
(1)
Ground air supply - 0 to 5 psi
(2)
Water Safety Relief Manometer - F72951-1 (Fig. 602)
(3)
Bonding meter (Ref 20-22-01 I/C)
(4)
Closure plugs and cover items:
CAUTION: ATTACH SAFETY STREAMERS MADE OF HEAVY RED COTTON WEBBING TO ALL CLOSURE ITEMS PRIOR TO INSTALLING SUCH ITEMS IN THE AIRPLANE.
NOTE: Use the following listed closure items or equivalents. These items may be obtained as Fuel Tank and Vent System Testing Kit F80080-129. Two kits are required to check the center tank vent system.
(a)
Two Structural Vent Plugs - F80080-100
(b)
Two Vent Scoop Closure Plugs - F80080-88
(c)
One Float Valve Closure Plug - F80080-8
(d)
One Surge Tank Drain Tube Plug Assembly - F80080-55
(e)
One Surge Tank Pressure Door Assembly - F80080-82
(f)
One Vent Float Valve Stop Assembly - F80080-26
(g)
One Cross Over Vent Tube Plug Assembly - F80080-29
(h)
Two Structural Vent Cover Assemblies - F80080-56
(i)
Two Drain Valve Plugs - F80080-112
(j)
Two Tube Plug Assemblies - F80080-49
(k)
One Plug Assembly Jet Pump Nozzle Cover - F80080-131
594
May 01/01 BOEING PROPRIETARY - Copyright . - Unpublished Work - See title page for details. 28-13-0 Page 601
C. Prepare for Vent System Pressure Check
WARNING: DO NOT COMPROMISE THE SAFETY PRECAUTIONS GIVEN FOR PURGING AND FUEL TANK ENTRY.
(1)
Fuel Tank No. 1 or 2 Vent System (Fig. 601).
(a)
Defuel and purge surge tank and wing tank for entry on side of airplane to be checked (Ref 28-23-0 and 28-10-0 MP).
(b)
Remove wing fuel tank access panels No. 1, 12, 13 and 14 (Ref 28-11-11 R/I).
(c)
Enter wing tank through No. 1 panel and rib access openings No. 2 and No. 1. Block off wing tank vent and drain hole by installing a crossover vent tube plug assembly F80080-29 in inboard end of vent. If performing pressure check of tank No. 1, block off fuel scavenge jet pump nozzle by installing jet pump nozzle cover plug assembly F80080-131.
(d)
Enter surge tank through No. 13 panel and block off center tank vent duct and surge tank drain. 1) Install structural vent plug, F80080-100-in center tank (FWD) vent duct. 2) Install structural vent cover assembly, F80080-56, in rectangular slot in center
tank (FWD),vent duct. 3) Install surge tank drain tube plug assembly, F80080-55, on opening to surge tank drain line.
(e)
Block off No. 13 panel opening by installing a surge tank pressure door assembly F80080-82 (Ref 28-11-11 R/I).
(f)
Block off No. 14 panel opening by installing a vent scoop closure plug, F80080-88.
(g)
Enter main tank through No. 12 panel opening to gain access to vent float valve. Block off float valve by installing vent float valve stop assembly F80080-26.
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