28-11-00
ALL ú ú 05 Page 239 ú Jun 10/97
BOEING PROPRIETARY - Copyright (C) - Unpublished Work - See title page for details.
A
747-400 MAINTENANCE MANUAL
2) Open the center wing tank access door (AMM 28-11-01/401). 3) Open the purge tank access door for the center wing tank, if necessary (AMM 28-11-06/401).
4) CENTER WING TANK (OPTION 1); Put the four inch air duct inside the open access door where you will do the maintenance. a) Use the pigtail on the end of the air duct to bond the
air duct to the airplane structure. b) Make sure there will be a flow of air into the area where you will do the maintenance.
5) CENTER WING TANK (OPTION 2 AND 3); Attach the air duct at the opening in the purge tank door. a) Seal the area around the air duct and the opening. b) Use the pigtail on the end of the air duct to bond the
air duct to the airplane structure. c) Make sure there will be a flow of air into the area where you will do the maintenance.
S 482-457
(4) After the air supply has operated for approximately 30 minutes, put the sampling line of the combustible gas indicator (Fig. 205) as far into the fuel tank as possible.
NOTE: It is recommended that you take the combustible gas indicator
____ value regardless of the type of fuel that was contained in the fuel tank. If the fuel tank had contained kerosene only, then the combustible gas indicator should show zero. This shows that the tank atmosphere is in fire-safe and health-safe condition.
S 482-458
(5)
Wait one minute for each foot of sampling line before you take a reading.
S 482-459
(6)
Use Table 202 to convert the values on the combustible gas indicator to the actual levels.
NOTE: If you use a combustible gas indicator that is not listed
____ below, follow the manufacturer's instructions to get the actual values.
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28-11-00
ALL ú ú 05 Page 240 ú Oct 15/98
BOEING PROPRIETARY - Copyright (C) - Unpublished Work - See title page for details.
A
747-400
MAINTENANCE MANUAL
~................................................................. | COMBUSTIBLE GAS | FOR PPM MULTIPLY | FOR LEL, MULTIPLY | | INDICATOR | VALUE BY: | VALUE BY: | ................................................................... |GASTECH 1314 | 2 | 3 | ................................................................... |GASTECH 1314SMPN | 2 | 3 | ................................................................... |GASTECH GT SERIES | 2 | 3 | 2.....................….....................….....................1
Table 202
S 492-460
WARNING: DO NOT USE A HEATER/AIR BLOWER UNTIL THE FUEL VAPOR
_______ CONCENTRATION IS 10% OR LESS OF THE LOWER EXPLOSIVE LIMIT AS SHOWN BY A COMBUSTIBLE GAS INDICATOR. IF THE FUEL VAPOR CONCENTRATION IS NOT 10% OR LESS OF THE LOWER EXPLOSIVE LIMIT, IGNITION OF THE FUEL VAPORS COULD OCCUR.
(7) When the combustible gas indicator shows the fuel vapor concentration is 10% or less of the lower explosive limit, you can put warm or cool air in the fuel tank through the tank access opening with an explosion-proof heater/air blower.
NOTE: The use of warm or cool air is for the comfort of
____ persons in the fuel tank. It is not part of the purging procedure.
S 492-461
WARNING: DO NOT STOP OR START THE HEATER/AIR BLOWER WHILE THE AIR DUCT
_______ IS IN THE FUEL TANK. THE FUEL VAPOR FROM THE FUEL TANK COULD CAUSE AN EXPLOSION AT THE HEATER OR BLOWER MOTOR. A FIRE OR EXPLOSION CAN CAUSE SERIOUS INJURY OR DEATH TO PERSONS AND CAN CAUSE DAMAGE TO EQUIPMENT.
(8)
Start the heater/air blower before you put the air duct in the fuel tank.
S 492-462
(9)
Put the air duct for the heater/air blower in the fuel tank through the tank access opening.
(10) 中国航空网 www.aero.cn 航空翻译 www.aviation.cn 本文链接地址：747-400 AMM 飞机维护手册 燃油 FUEL 1(49)
