A
ALTERNATE STATIC PORTS 1
RIGHT SIDE SHOWN: LEFT SIDE SIMILAR
B
2 GUN 004-007
Pressurization Indicating and Warning System Adjustment Test
Figure 501
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A
757 MAINTENANCE MANUAL
F. Do the Cabin Pressure Warning Test
S 735-005
(1)
GUN 004-007;
Do the High Altitude Warning Switch Test
(a)
Remove the pneumatic tubing from the high altitude warning switch, S10553, in the left miscellaneous electrical equipment panel, P36.
(b)
Connect the vacuum pump to the high altitude warning switch.
(c)
Push the HIGH ALT LDG switch-light, on the P5 panel, to on.
1) Make sure the ON light comes on and the INOP light does not come on.
(d)
Increase the vacuum pressure (Pvac) to the equivalent cabin altitude of 14,600 ft (8.4 psia). Do not increase the vacuum pressure at a rate greater than 4000 ft/min (2.0 psi/min).
NOTE: The vacuum pressure (Pvac) necessary to get the
____ equivalent cabin altitude of 14,600 ft (8.4 psia) is calculated as follows: Pvac = Pambient - 8.4 At sea level, Pamb = 14.7 psia. Thus, at sea level Pvac = 6.3 psig
(e) Make sure these indications occur: 1) The aural warning siren comes on. 2) The two WARNING lights, on the pilots' lightshield, come
on. 3) The CABIN ALT light, on the Captain's Main Instrument Panel
P1-3, comes on. 4) The CABIN ALTITUDE light, on the P5 panel, comes on. 5) The EICAS advisory message CABIN ALTITUDE shows on the
display.
(f)
Decrease the vacuum pressure, at a rate not greater than 4,000 ft/min (2.00 psi/min), to 12,500 ft (9.00 psia).
(g)
Push the HIGH ALT LDG switch-light, on the P5 panel, to off. Make sure the ON light goes off.
(h)
Make sure these indications occur: 1) The aural warning siren goes off. 2) The two WARNING lights, on the pilots' lightshield, go off. 3) The CABIN ALT light, on the P1-3, goes off. 4) The CABIN ALTITUDE light, on the P5 panel, goes off. 5) The EICAS advisory message CABIN ALTITUDE does not show on
the display.
(i)
Decrease the vacuum, at a rate not greater than 4,000 ft/min
(2.00 psi/min), to the ambient pressure (14.70 psia at sea level).
(j)
Remove the vacuum source from the high altitude warning switch, in the P36 panel.
(k)
Attach the pneumatic tubing to the high altitude warning switch.
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21-33-00
ALL ú ú 02 Page 503 ú May 20/98
BOEING PROPRIETARY - Copyright (C) - Unpublished Work - See title page for details.
A
757
MAINTENANCE MANUAL
S 735-007
(2)
Do the Cabin Altitude Warning Switch Test
(a)
Find the altitude warning switch, S431, in the P36 panel.
(b)
Connect the vacuum pump to the altitude warning switch.
(c)
Increase the vacuum pressure (Pvac) to 11,050 ft (9.70 psia), at a rate no greater than 4,000 ft/min (2.00 psi/min).
NOTE: The vacuum pressure (Pvac) necessary to get the
____ equivalent cabin altitude of 11,050 ft (9.70 psia) can be calculated as follows: Pvac = Pambient - 9.70 At sea level Pamb = 14.7 psia. Thus Pvac at sea level is 5.0 pisg.
(d) Make sure these indications occur at 10,000 | 300 feet: 1) The aural warning siren comes on. 2) The two WARNING lights, on the pilots' lightshield, come
on. 3) The CABIN ALT light, on the pilots' center instrument panel
P1-3, comes on. 4) The CABIN ALTITUDE light, on the P5 panel, comes on. 5) The EICAS advisory message CABIN ALTITUDE shows on the
display.
(e) Decrease the vacuum, at a rate not greater than 4,000 ft/min
(2.00 psi/min), to 7,500 ft (11.1 psia).
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