Other AC Systems Flashcards
How does a pressurized AC work?
There is a sealed ‘pressure vessel’ inside the AC where pressurized air gets pumped in to the vessel to basically inflate it like a baloon.
Each AC has a max Pressure Difirential. What is this?
Related to pressurization.
If the PSI of the outside air at sea level is 14.7 and you are cruising at 35000 ft where the PSI is 3.5, you set the cabin pressure to 8000 ft, which has a PSI of 10.9.
10.9 - 3.5 = 7.4 PSI
An airliner probably has a max pressure diffirential of 8 so this pressurized setting is fine. If you were to exceed it by setting the cabin altitude to too low a value (say sea level), the pressure vessel (cabin) could explode.
How do AC with jet engines or piston engines pressurize the cabin?
Jet engine - bleed air
Piston - turbo charger
What types of instruments use the vaccum pump?
Anything with a gyro
What three ways is the vacuum system operated and which is the most common?
- Engine driven vacuum pump (most common)
- Venturi (usually found only in classic ‘vintage’ AC. Simple, cheap, doesnt work at slow airspeeds or in icing conditions)
- Electric motors (more reliable but more expensive)
On your checklist is says to check the suction guage. What do the values on this guage represent?
Typically gyros need between 4 and 6 inches of mercury pressure difference to operate. The suction guage green arc represents these figures.
Why is the vacuum pump one of the most unreliable/delicate/often replaced peices of equipment in an AC?
because the carbon sticks inside grind down so fast, they break off and bust up the other ones inside and make it useless.
Needs to be replaced every 500 hours or so.
Old venturi vacuum system and why are they not great?
You have to get moving before it can work. Super susceptible to blockage/icing
What is the difference between de-icing systems and anti-icing systems?
De-icing is to get rid of ice that has already formed
Anti-ice is to prevent ice from forming in the first place
The TKS anti-ice system is a bunch of pinholes in the leading edge of the wing that let glycol seep out and back over the wing. What are the main disadvantages of this system?
You can run out of glycol. It’s heavy (heavier than fuel, so eats into useful load), the holes can get plugged.
What three types of rigging are there?
- Cables (cessna)
- Pushrod (diamond)
- Fly by wire (more advanced AC. Movement of control column sends an electrical impulse to a hydraulic system
What should you do if you lose control of your elevator control system and why?
The trim system, because it is rigged seperately. POH would have exact procedure.
Why is knowing and understanding what systems your airplane uses so important?
So you can know/figure out ways to to keep flying if you lose one of those systems
What is an outflow valve for in pressurized AC?
It regulates the pressure by letting some bleed out if too much air is being put in so the cabin doesnt explode
