**Aircraft Pressurization**

Question 1

When aircraft are pressurized on the ground, stay clear of ____, ____, _____, and _____.

Answer 1

Doors, windows, escape hatches, and access panels

Question 2

Aircraft pressurized to just 15 inches of mercury has a pressure of approximately ___, therefore an aircraft panel 10x10 will exert ___lbs of outward force.

Answer 2

7psi, 700lbs

Question 3

The atmosphere is composed of ____ nitrogen and _____ oxygen, while carbon dioxide, water vapor, and ozone make up the remaining ___ of atmospheric gases.

Answer 3

78%, 21%, 1%

Question 4

On a standard day, atmospheric pressure at mean sea level is what psi or how many inches of mercury?

Answer 4

14.7psi or 22.92in

Question 5

Standard day temperature is ___ or ___. As altitude increases, temperature decreases at a rate of about -2 C every ___ft.

Answer 5

59F or 15C, 1000

Question 6

Who decided upon the conditions for standard day to be used in all aircraft and engine performance computing?

Answer 6

International Civil Aviation Organization (ICAO), a specialized agency of the United Nations.

Question 7

What are the three requirements for aircraft pressurization?

Answer 7

A sealed aircraft cabin, a source of temperature controlled compressed air, and a method of controlling the cabin pressure.

Question 8

What are the two types of leaks that can occur in pressurized aircraft? describe each.

Answer 8

Controlled leakage- air is allowed to escape through a valve to regulate pressure in the aircraft. Uncontrolled leakage- air leaks around hatches, doors, and drains.

Question 9

Sealant is used on what structures to create a permanent pressure seal?

Answer 9

Metal seams, windows, and similar structures.

Question 10

What type of seals are used around removable windows and doors and why?

Answer 10

Hollow rubber seals: these seals have air holes along the side of the seal facing the inside of the cabin. When the aircraft is pressurized, pressure from the cabin enters the seal through these holes to inflate the seal and provides a positive seal between the door or window and airframe.

Question 11

Compressed air is used to pressurize and maintain a comfortable environment during high altitude flights. Where does this air come from?

Answer 11

Bleed air from the compressor section of the power plant is directed through the air manifold, ECS and into the cabin.

Question 12

In automatic mode, the pressure controller has two knobs: RATE and CABIN ALT. Using rate control, cabin altitude maximum rate of climb or descent can be selected from ___ to ___ fpm. Using cabin alt, desired cabin altitude can be selected from ____ft below sea level to ___ above sea level.

Answer 12

50-2000ft, 1,000 below to 10,000 above

Question 13

Rate control knob in a HC-130H may select any rate between __ and ___ ft per minute.

Answer 13

30 and 2,900

Question 14

What does the Altitude at Maximum Differential window display?

Answer 14

The maximum altitude the aircraft can fly and maintain the selected cabin altitude.

Question 15

In manual mode, What does the manual pressurization switch control?

Answer 15

The position of the outflow valve.

Question 16

Describe the safety valve used with manual pressurization.

Answer 16

An electrically-controlled and pneumatically-operated butterfly valve. Senses differential pressure and automatically provides relief of over-pressuization and relief of negative pressure.

Question 17

In the event of an emergency, the emergency depressurization switch can be actuated, and what three things will occur?

Answer 17

Outflow valve will open, safety valve will open, and air conditioning will shut down.

Question 18

What aircraft has an emergency depressurization door to be used in the event the emergency depressuization switch fails? What acutates this door?

Answer 18

C-130s, emergency depressurization T-handle in the cockpit

Question 19

Cabin pressurization systems must be capable of maintaining cabin pressure altitudes of ____ft or lower regardless of aircraft altitude to ensure crew has enough oxygen to facilitate ______________.

Answer 19

8,000 - full blood saturation