(c) When the electrical test is started, the NGS controller monitors the NGS system
performance. The NGS controller will stop the test if there is a change in the airplane
configuration as noted previously. The electrical test can also be stopped manually if the
MENU or ON/OFF push button controls are pushed during the test. If the electrical test is
stopped before the test is fully done, all latched electrical faults that were present prior to
the start of the test will continue to be recorded as latched faults.
(6) NGS Performance IBIT
(a) There are two manually initiated BDU tests done by the NGS controller to test the NGS
performance:
1) NGS PERF LO FLOW?
2) NGS PERF HI FLOW?
(b) The two tests are done when the NGS system is pressurized. The NGS PERF LO FLOW
test, does a check of the NGS in the low flow mode. The NGS PERF HI FLOW test, does
a check of the NGS in high flow mode. To do the NGS performance tests, it is necessary
to pressurize the NGS with bleed air pressure and operate the left air conditioning pack.
The left air conditioning pack is also operated to increase the bleed air pressure during
the test. It is necessary to warm up the ASM to the operating temperature of 160 ±10°F
(71 ±6°C). To do a check the performance of the ASM, a GSE Oxygen Analyzer is
attached to Nitrogen-Enriched Air Distribution System (NEADS) line. The oxygen
analyzer records the % oxygen against the system pressure to check the purity of the
Nitrogen-Enriched Air (NEA) produced by the ASMs.
(c) When the BDU starts the NGS PERF LO FLOW test, the NGS controller commands the
NGS shutoff valve and overtemperature valve to ON. The high-flow valve is commanded
closed. The NGS ram air valve controls the ASM inlet temperature within the standard
temperature range limits. The test continues until the MENU or ON/OFF control
push-buttons are pushed.
(d) When the BDU starts the NGS PERF HI FLOW test, the NGS controller commands the
NGS shutoff valve and overtemperature valve to ON. The high-flow valve is commanded
open. The NGS ram air valve controls the ASM inlet temperature within the standard
temperature range limits. The test continues until the MENU or ON/OFF control
push-buttons are pushed.
(e) The NGS controller will not start the test or stop the test if the airplane configuration is
incorrect. This includes NGS inlet pressure less than 15 psig (103 kPa), the airplane is in
air mode, the packs are off, the center wing tank refuel valves open, or an invalid aircraft
ID is set. The NGS controller will also not start the test if another BDU ground test is
in-progress.
(f) If an existing fault is recorded for one or more of these LRUs', the NGS controller will not
start the test:
1) NGS controller (drivers and sensor interfaces)
2) NGS shutoff valve
3) Overtemperature shutoff valve
4) NGS ram air valve
5) ASM High-flow valve
6) NGS bleed air pressure sensor
7) NGS Temperature sensor
8) ASM differential pressure sensor.
737-600/700/800/900
AIRCRAFT MAINTENANCE MANUAL
47-31-02
Page 234
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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