Pressurization

Question 1

“Big” P3 components:

Answer 1

Pressurization and Heating

Question 2

“Little” P3 components:

Answer 2

Pneumatic systems

Question 3

Describe the motion of Uncontrolled Pressurization Airflow (P3):

Answer 3

1) In from engines
2) Forward to mixing plenum
3) Rearward into cabin

Question 4

Describe the motion of Controlled Pressurization Outflow:

Answer 4

Exits through Outflow Valve at rear pressure bulkhead and ducts into the unpressurized tailcone, then overboard

Question 5

Describe the Ambient Air Intakes:

Answer 5

Located in fire shield under intake screens.

Used to moderate temperature of P3 air once airborne.

Question 6

Describe the Ambient Air Sensor:

Answer 6

Samples ambient air temp to meter ambient airflow into system

Question 7

Pressurization Control Unit- Flow Pack

Answer 7

Admits hot P3 air for pressurization and heating.

Admits cool ambient air to moderate high P3 temps.

Question 8

Bleed Air Valves

Answer 8

Valve to control pressurization airflow.
Located on the flow pack.
Valve is controlled by cockpit bleed air switch.
-In open, power applied to open environmental valves on pressurization flow packs.
-In middle and down positions, power is removed from these valves, they close, and there is no pressurization or heating from that engine.

Question 9

Max. differential pressure:

Answer 9

200: 6.1 psid
B200: 6.6 psid

Question 10

Max flight time with cracked windshield:

Answer 10

25 hours

Question 11

Max altitude and pressure differential with cracked windshield:

Answer 11

25,000’

4 psid

Question 12

R/L BL AIR OFF

Answer 12

indicates switch position of bleed air valves. NOT in the open position

Question 13

Safety Valve

Answer 13

Hooked to Dump Solenoid (NC)
Capped.
Pressure dump Capability.
Overpressure protection
Negative differential relief

Question 14

Outflow Valve

Answer 14

Vented into cabin pressure
Hooked to Preset Solenoid (NO)
Pressurization outflow control
Overpressure protection
Negative differential relief

Pressure controller provides vacuum to outflow valve to control airflow leaving pressure vessel

Question 15

Schrader Valve

Answer 15

Located in Safety Valve and Outflow Valve. Compares cabin pressure to tailcone. If differential pressure exceeds 6.5 PSID (B200) valve will cycle to relieve excess pressure. I.e. Overpressure protection

Question 16

Ram Air Inlet Door

Answer 16

Located at forward end of pressure vessel.
Held closed by permanent and electromagnet.
Opens to admit outside air once cabin air PSID is reduced to less than 1 by selecting DUMP with the pressurization switch.

Question 17

Ambient Air Valve

Answer 17

Located on Pressurization Control Unit (Flow Pack). Controls cooling airflow, by valve movement. Controlled by Ambient Temp Sensor. Valve closes around 0F (electric) or -30F (pneumatic)

Question 18

Cabin Pressurization Switch

Answer 18

In (PRESS) position, power is removed from system:

• Dump valve is closed
• Preset valve is open
• Door seal valve is open
• Ram air door held closed by electromagnet

In (TEST) on ground, the left main gear safety switch is bypassed, causing the above (i.e. pressurization)

Question 19

Pressurization Controller

Answer 19

Upper chamber vented to monitor pressure altitude.

Sealed lower chamber contains aneroid (for cabin alt), and adjusts vacuum on outflow valve.

Question 20

Cracked Windshield

Answer 20

Descend to 25,000 or less
Reduce cabin pressure to 4.0 psid
DO NOT DUMP
Oxy masks as necessary

Question 21

Pressurization Control CB

Answer 21

Pressurization switch (pedestal)
Outflow control solenoid valve (NO)
Safety control solenoid valve (NC)
Cabin door solenoid valve (NO)
Ram Air Door electromagnet
Left Landing Gear Safety switch

Question 22

Bleed Air Control CB

Answer 22

Bleed Air Valve switches
Bleed Air Off lights
Environmental flow packs
Pneumatic shutoff valves
Rudder Boost Control