NITROGEN-ENRICHED AIR DISTRIBUTION - INSPECTION/CHECK
1. General
A. This procedure contains scheduled maintenance task data.
B. This procedure contains these tasks:
(1) Drain Cap - Fuel Leak Check
(2) NEADS - Air Pressure Leak Check
(3) NEADS - Negative Pressure Leak Check
C. The fibers in the Air Separation Module (ASM) is damaged by fuel or fuel vapor. Protection from fuel
contamination is supplied by two backflow protection check valves in the Nitrogen-Enriched Air
Distribution System (NEADS) line. If there is a problem with a check valve or a leak in the NEADS
line, fuel leakage can be detected at the drain cap attached to the NEADS drain line.
D. The drain cap is installed below and inboard of the ASM. The drain line is at the lowest area of the
NEADS line where water, fuel, and sediment collects. You must periodically inspect the NEADS line
to make sure that the NEADS line does not contain fuel.
E. The NEADS - Negative Pressure Leak Check can be used to make sure that the primary backflow
prevention check valve operates correctly.
TASK 47-21-00-700-802
2. Drain Cap - Fuel Leak Check
NOTE: This procedure is a scheduled maintenance task.
A. References
Reference Title
12-33-01-600-802 Cold Weather Maintenance Procedure (P/B 301)
B. Tools/Equipment
Reference Description
STD-195
Container - 1 Quart (1 l), Oil/Fuel Resistant
C. Location Zones
Zone Area
131 Center Section Wing Box, Body Station 540.00 to Body Station 663.75 - Left
D. Access Panels
Number Name/Location
192BL ECS Ram Air Inlet Mixing Duct Panel - Forward
E. Prepare for the Procedure
SUBTASK 47-21-00-010-003
(1) Open this access panel:
Number Name/Location
192BL ECS Ram Air Inlet Mixing Duct Panel - Forward
SUBTASK 47-21-00-660-001
(2) If the ambient temperature is less than 32°F (0°C), do this task: Cold Weather Maintenance
Procedure, TASK 12-33-01-600-802.
737-600/700/800/900
AIRCRAFT MAINTENANCE MANUAL
47-21-00
Page 601
D633A101-ILF Oct 15/2019
ECCN 9E991 BOEING PROPRIETARY - Copyright © Unpublished Work - See title page for details
EFFECTIVITY
ILF 402, 452, 509, 510, 523, 525-528, 568, 569, 576, 577, 581, 583, 585, 588-590,
592-599, 601-603, 606, 607, 610-615, 620, 625-627, 691-699, 833-835, 838, 971, 980-999;
ILF 101, 151, 156-199, 301, 304, 308, 310, 314, 315, 317-319, 323, 331-399, 401, 405,
406, 409, 410, 412, 416, 424, 425, 427-429, 451, 501-504, 507, 508, 512-514, 516, 518,
524, 531-533, 535-537, 541, 542, 552-556, 560-562, 567, 571-575, 671, 672, 686, 703,
707-710, 803-813, 821, 822, 831, 832, 836, 837, 841, 842, 851, 852, 854-858, 861-863,
871-874, 947, 948, 968-970, 972, 973 POST SB 737-47-1003
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