1. Pressurization

2. Why pressurization? Humans have trouble breathing at higher altitudes…
Sea Level – 100%
10,000 ft – 90%
15,000 ft – 75%
20,000 ft – 40%
25,000 ft – 0%

3. Why pressurization?
This results in a diminishing time of useful consciousness (TUC)…
20,000 ft – 30 minutes
25,000 ft – 3 – 5 min
30,000 ft – 1 – 4 min
35,000 ft – 30 – 60 sec
40,000 ft – 15 – 20 sec
45,000 ft – 9 – 15 sec!

4. How much pressurization?
Based on differential pressure
Ratio of outside pressure (at altitude) to inside pressure
Beech Baron – 3.6 PSID
Altitude 15,000’ – cabin 6,000’
Boeing B-737 – 7.8 PSID
Altitude 37,000’ – cabin 8,000’
Chart on next page

6. Requirements for pressurized flight
Cabin strong enough to withstand pressure differential
Source of pressurized air
Drawn from turbocharger or supercharger
Turbine engine uses bleed air from compressor
Method to control pressurization
Cabin pressure controller
Outflow valve(s)

7. Source of pressurized air
Air Pump
Roots – type
Vane type
Hydraulic lesson

8. Pressurization Control Panel
Rate Selector Knob
Control pressure changes
Cabin Altitude Selector Knob
Sets desired cabin altitude
Barometric Pressure Correction Knob

9. Pressurization Control Panel

10. Pressurized Flight Profile

11. Pressurization System

12. Larger Aircraft Similar
Higher pressurization differentials
Same Basic Components
Source,
Control Mechanism
Outflow Valves

15. Pneumatics