AMT 2204 AUXILIARY REVIEWER

Two different Aircraft cabin pressurization modes of operation

Isobaric Mode and Constant Differential Mode

It works to maintain cabin altitude at a single pressure despite the changing altitude of the aircraft.

Isobaric Mode

Isobaric mode. If the flight crew selected to maintain a cabin altitude of 8,000 feet (10.92psi), the cabin pressure is established at what altitude level and remains at this level?

8,000 feet level

It controls cabin pressure to maintain a constant pressure difference between the air pressure inside the cabin and the ambient air pressure, regardless of aircraft altitude changes.

Constant Differential Mode

It means the outside pressure.

Ambient air pressure

True or False
Constant differential mode pressure differential is lower than the maximum differential pressure, for which the airframe is designed.

True

True or False
When the aircraft climbs beyond a certain altitude, Isobaric mode may switch to constant differential mode.

True

The rate of change of the cabin pressure.

Cabin rate of climb or descent

Typical rates of change for cabin pressure are?

300 to 500 fpm.

Modes of pressurization may also refer to _______ versus _______ versus _______ operation of the pressurization system.

automatic versus standby versus manual

The device used to control the cabin air pressure.

Cabin pressure controller

It opens, closes, or modulates to establish the amount of air pressure maintained in the cabin.

Cabin outflow valve

True or False
Controlling the cabin pressure and the exchange of air from the inside of the aircraft to the outside, ensures comfort.

True

True or False
In order to be able to fly at high attitudes, the aircraft needs to be pressurized so that the crew and passengers can breathe without the need for supplemental oxygen.

True

It is used to pressurize the cabin which the air is released from the cabin by an Outflow Valve.

Bleed Air

Used to manage the flow of air through the outflow valve.

Cabin pressure regulator

True or False
As an aircraft descend. the pressurization system will gradually increase the cabin altitude and the differential pressure at the same time.

False. Climb

True or False
The maximum cruise altitude will be limited by the need to keep the cabin altitude at or below 10,000 ft.

False. 8,000 ft.

Safety valve acts as
a. a relief valve
b. a vacuum relief valve
c. a dump valve
d. all of the above

d. all of the above

Releasing air from the cabin to prevent the cabin pressure from exceeding the maximum differential pressure.

Relief Valve

Allowing air into the cabin when the ambient pressure exceeds the cabin pressure

Vacuum relief valve

Allowing the crew to dump cabin air manually.

Dump valve

The following help the crew to monitor the aircraft pressurization, except
a. Cabin Altimeter
b. Differential Pressure Gauge
c. Cabin Rate of Climb gauge
d. None of the above

d. None of the above

True or False
As we climb in altitude, the amount of air pressure acting on us decreases rapidly.

True

True or False
As we climb higher, air molecules are spread farther apart.

True

At 18,000 feet, the atmospheric pressure is down to how many psi, about half the sea-level pressure.

7.3 psi

At this pressure (7.3 psi), a healthy adult has only how many minutes of useful consciousness.

20-30 minutes

True or False
Airliners fly between 30,000 and 43,000 feet.

True

Disadvantages of flying below 10,000 ft

• It’s tough to cross a 14,000 foot mountain range at 10,000 ft.

• Most bad weather is at lower altitudes.

• Turbofan engines are very inefficient down low.

• Aircraft ground speeds are slower at lower altitudes.

True or False
The wing is capable of withstanding a fair amount of differential air pressure.

False. Fuselage

To control the interior pressure, and allow old, stinky air to exit, there is a motorized door called an ______.

Outflow valve located near the tail of the aircraft.

Larger aircraft often have how many outflow valve?

Two outflow valves

True or False
If higher pressure is needed inside the cabin, the door opens.

False. Closes

True or False
To reduce cabin pressure, the door slowly opens, allowing more air to escape.

True

One of the benefit of a pressurization system

constant flow of clean, fresh air moving through the aircraft.

The air inside the airplane completely changes every
a. 2 to 3 minutes
b. 20 to 30 minutes
c. 1 to 2 minutes

a. 2 to 3 minutes

Pressurization systems are designed to keep the interior cabin pressure between how many psi at cruise altitude.

12 and 11 psi

True or False
As the aircraft climbs to 36,000 feet, the interior of the plane “climbs” to between 6000-8000 feet.

True

Why not keep the cabin at 14.7 psi to simulate sea-level pressure and maximize comfort?

The aircraft must be designed to withstand differential pressure

The difference between the air pressure inside and outside the aircraft.

Differential pressure

True or False
The greater the differential pressure, the stronger (and heavier) the airplane must be built.

True

The maximum differential pressure

12 psi

Two types of mechanical devices to protect the pressurized section of the aircraft against excessive pressure differential.

Positive Pressure Relief Valves
Negative Pressure Differential Relief Doors

Sometimes called butterfly valves; are spring-loaded to vent excess air pressure when cabin pressure exceeds the maximum limit.

Positive Pressure Relief Valves

Means the pressure outside the cabin is greater than the pressure inside the cabin.

Negative Pressure Differential Relief Doors

True or False
Negative pressure is good because it pushes inward on doors and windows.

False. Bad

Old piston powered airliners, like the Boeing Stratocruiser, used what kind of compressors to pump fresh, outside air into the cabin.

Electric Compressors

Early jetliners, like the Douglas DC-8 and Boeing 707 used bleed air from the engines to spin what kind of compressor.

Turbo compressor

Most modern airliners use what kind of air from the compressor section of the engines to pressurize the cabin.

Engine Bleed Air

HOW DO PILOTS CONTROL THE PRESSURIZATION?

pilots turn the “LDG ALT” knob to display the altitude of the landing airport.

True or False
The air inside an aircraft cabin is very high in humidity.

False. very low

True or False
On a long flight it’s important to drink plenty of alcohol to stay hydrated.

False. Water

note: alcohol increases dehydration.

True or False
The aircraft cabin’s low humidity and lower air pressure reduce your sense of taste and sight by as much as 30%.

False. sense of taste and smell

Provides air supply, thermal control and cabin pressurization for the crew and passengers.

Environmental control system (ECS)

Are also commonly considered part of an aircraft's environmental control system.

Avionics cooling
Smoke detection
Fire suppression

Are designed to store or to generate a supply of pure oxygen and to regulate, dilute as required and then distribute that oxygen to crew or passengers.

Oxygen systems

True or False
Oxygen system may be used in the event of smoke, fire, fumes or loss of pressurization.

True

National regulations for the provision and use of supplemental or emergency oxygen systems are based on the guidance provided in

Annex 6 of the ICAO-SARPS

An _______ shall ensure that passengers are made familiar with the location and use of oxygen dispensing equipment.

Operator

Approximate hPa-altitude equivalents:

700 hPa = 10,000'
620 hPa = 13,000'
376 hPa = 25,000'

The higher the altitude, the lower the Time of ________

Useful Consciousness