(O) One may be inoperative provided:
a) Flight is conducted unpressurized,
b) Air Source Selector remains in FRESH AIR or OFF,
c) All other components and functions of the pressurization system operate normally, and
d) Crew and passengers comply with any applicable oxygen requirements.
OPERATIONAL PROCEDURES
1. Start both engines and turn off the Air Cond and Defog switches and select manual COLD.
2. Select the BOTH position on Air Source Select switch.
3. Press and hold the EXER button on display face of Cabin Pressurization Controller for two minutes and observe Cabin Differential Pressure Gauge.
4. If the gauge remains constant the Flow Control Valve has failed in the closed position.
5. Select Air Source Select switch to OFF.
6. Place a placard stating, “Select FRESH AIR or OFF only – (LH/RH) Flow Control Valve INOP” above the switch.
7. Make appropriate entry on the discrepancy report.
(O) One may be inoperative provided:
a) The affected pressure regulating shutoff valve is verified in the closed position, and
b) All other components and functions of the pressurization system operate normally.
OPERATIONAL PROCEDURES
1. Start both engines and turn off the AIR CONDITIONING and DEFOG switches and select TEMPERATURE SELECT to MANUAL, COLD.
2. Select left and right sources independently on the AIR SOURCE SELECT switch.
3. Press and hold the EXER button on display face of Cabin Pressurization Controller for two minutes and observe Cabin Differential Pressure Gauge.
4. If the gauge remains constant, the Pressure Regulating Shutoff Valve has failed in the closed position.
5. Place a “(RH or LH) SOURCE INOP” placard next to the AIR SOURCE SELECT Switch at the inoperative position.
6. Make appropriate entry on the discrepancy report.
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