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MAINTENANCE MANUAL
(b) Make sure that these values show on the ECS area of the main EICAS:
~..................................................
| CAB ALT | (present field elevation |500 ft) | ....................................................
| LDG ALT | (any value) | ....................................................
| RATE | 0 |200 ft/min | ....................................................
| .P | 0 |0.4 psid | 2............….....................................1
(c) Apply vacuum at a rate of 2000 ft/min. 1) Make sure that the CAB ALT values increase. 2) Make sure that RATE is approximately 2000 ft/min. 3) Make sure that the .P values are negative and that they increase.
(d) (e) Decrease the vacuum rate to 500 ft/min when the CAB ALT value becomes approximately 8000 ft. 1) Make sure that the CAB ALT value changes from white to amber color at approximately 8500 ft. 2) Make sure that these occur when the CAB ALT value becomes 10,000 |300 ft: a) The aural warning siren starts. b) The master warning lights come on. c) The EICAS warning message CABIN ALTITUDE shows. d) The CAB ALT value changes from amber to red color. 3) Push either MASTER WARNING light to stop the siren.Stop the vacuum increase and then start the rate at -500 ft/min. 1) Make sure that these occur when CAB ALT becomes approximately 9500 ft: a) The EICAS warning message CABIN ALTITUDE does not show. b) The CAB ALT value changes from red to amber color. 2) Make sure that the CAB ALT display changes from amber to white color when the CAB ALT value becomes approximately 8000 ft.
(f) Stop the vacuum decrease when CAB ALT reaches approximately 7000 ft.
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F. Do the Cabin Altitude Sensors Disagreement Test
S 715-071
(1) Make sure that there is backup sensor failure indication:
(a)
Turn the valve on the vacuum harness to the closed position. This will make a seal of the vacuum to one of the cabin pressure controllers.
(b)
Apply vacuum at a rate of 500 ft/min until the CAB ALT value is 8100 ft, and hold the vacuum for 60 seconds. 1) Make sure that the EICAS status message CPCS BACKUP SENS
shows.
(c)
Decrease the vacuum at -500 ft/min until the CAB ALT value is approximately 7000 ft.
(d)
Turn the valve on the vacuum harness to return the vacuum to both controllers.
(e)
Decrease the vacuum at a rate of 4000 ft/min until it is at ambient pressure.
(f)
Push the MAN L and MAN R switches on the CPCS selector panel to the off position.
G. Put the airplane back to its usual condition
S 085-075
(1)
Disconnect the vacuum harness from the face of each cabin pressure controller.
S 865-070
(2)
Remove the electrical power, if it is not necessary
(AMM 24-22-00/201).
TASK 21-31-00-705-122
7. Cargo Fire Control Decompression System Operational Check
_________________________________________________________
NOTE: This is a scheduled maintenance task
____
A. Equipment
(1) G21002-30, Breakout Box - ICU Altitude Switch
B. References
(1) AMM 24-22-00/201, Manual Control
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(2) AMM 32-09-02/201, Air/Ground Relay System
C. Access
(1) Location Zone
221, Control Cabin
151, Area Aft of Bulk Cargo Compartment, LH
152, Area Aft of Bulk Cargo Compartment, RH
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