AME T110 Carburetors (Class Origin) Flashcards
What is the main job of a Carburetor?
Maintain the correct Air / Fuel Mixture.
How does a Carburetor allow Throttle Adjustments?
By allowing the pilot to control the Throttle Plate.
What two ducts make up a Venturi?
A Convergent and Divergent Duct.
What are the three aspects of a Convergent Duct?
1) Velocity Increases
2) Pressure Decreases
3) Temperature Decreases
What are the three aspects of a Divergent Duct?
1) Velocity Decreases
2) Pressure Increases
3) Temperature Increases
More throttle means what?
More Power.
What does each Fuel Lever Position equate to in a Mixture sense?
a) Fuel Lever All-In.
b) Fuel Lever All-Out.
c) Full
a) All-in = Full Rich Mixture
b) All-Out = 8:1 Air / Fuel Mixture
c) Full = Engine Cut-Off.
One of the Carburetors jobs is to Atomize the fuel. What does this mean?
Atomizing the fuel means that it is being made into a mist.
What are the Six Systems of a Carburetor?
Float & Float Bowl
Main Metering System
Idle System
Mixture Control System
Economizer or Enrichment System
Accelerating System
What is the purpose of the Float and Float Bowl?
Supplies Fule to the Main Metering System.
What is the purpose of the Main Metering System?
Controls the amount of Air / Fule supplied to the engine under most operating conditions.
What is the purpose of the Idle System?
Controls the amount of Air / Fuel supplied to the engine during Low Power Settings.
What is the purpose of the Mixture Control System?
Allows the accurate adjustment of Manual or Automatic Mixing of the Air / Fuel Ratio during All Operating Conditions.
What is the purpose of the Economizer / Enrichment System?
Provides an Extra Rich Mixture for improved Cooling when the Throttle is at or near Full Open.
What is the purpose of the Accelerating System?
Adds Extra Fuel for cceleration whenever the Throttle is advanced.
What is the job of the Main Metering Jet?
To limit the maximum amount of Fule Flow at Full Powe.r
What two jobs does the Ambient Air Bleed component do?
Reduces Surface Tension.
Begins the Atomizing Process.
(The combination of the above processes is referred to as Emulsifying).
What is the job of the Idle Fuel Circuit?
Brings Fuel up and above the Throttle Plate during Idle.
How is the Float Level Maintained?
Through the use of a Float and Needle Valve.
The Floats control the needle valve and as the Float Level lowers, the needle valve opens allowing more fuel to replenish.
This raises the floats which closes the valve.
What are the three different types of Mixture Control Valves?
1) Step Cut Rotary Valve.
2) Needle Valve.
3) Back Suction Valve.
How is Automatic Mixture Control accomplished?
Through the utilization of an Aneroid Bellows.
What are the two types of Accelerator Systems?
Accelerator Pumps
Acceleraor Wells within the Fuel Nozzles.
What can High Cylinder Head Temperatures (CHT’s) lead to?
Pre-Ignition.
What are the three kinds of Economizer Systems?
1) Needle Type (Economizer Needle)
2) Air Bleed Economizer.
3) Impact Air System.
What are the two adjustments found on Carburetors?
Mixture Control and Idle Control.
What must be found on a Carburetor Data Plate?
Model No.
Make
Serial No.
How would you check Carburetor Floats for Leaks?
Put them underneath hot water and look for bubbles.
How would one measure the level of fluid the Floats are resting on?
Using a Glass Tube.
The Carburetor is seen to be leaking when the Engine is run.
What could be wrong?
Floats have sunk.
There has been damage to the Needle or Seat.
Why would the mixture be too Lean at Idle?
Three possible reasons
- A leak exists in the Intake Manifold.
- An obstruction exists within the Idle Metering Jet.
- The Idle Mixture is out of Alignment.
Why would the mixture be too Lean at Cruise?
Five possible reasons
- The Fuel Pressure is too Low.
- The Float Level is too Low.
- The Fuel Strainer is clogged.
- The Manual Mixture Control is not set properly.
- There is an Air Leak in the Intake Manifold.
Why would the mixture be too Lean at the Full Power Setting?
The Economizer is not operating properly.
Why would the mixture be too Rich at Idle?
Three possible reasons
- The Primer Line is Open.
- The Idle Mixture Conrol is out of Adjustment.
- Fuel Pressure is too High.
What is a Primer Line and what is its’ purpose?
What: A Fuel Injection Nozzle.
Purpose: Act as an Accelerator Nozzle that may be activated from the cockpit.
When would the Primer Line be used?
Only during the Starting Sequence.
Why would the mixture be too Rich at Cruise Power Settings?
Five possible reasons
- The Float Level is too High.
- The Manual Mixture is not set properly.
- The Economizer Valve is Open.
- THe Main Air Bleed is Clogged.
- Fuel Pressure is too High.
The aircraft is experiencing Poor Acceleration and the Engine is Backfiring when the Throttle is Advanced.
What is the issue?
(Three possible reasons).
- The Accelerating Pump is not working correctly.
- The Check Valve is Clogged.
- The Accelerator Nozzle is Jammed.
What does it mean when an Engine Backfires?
Explain.
A Backfire is an Intake FIre due to a Lean Mixture.
What does it mean when an Engine After-Fires.
Explain.
An After-Fire is caused by an Exhaust Fire and is due to too Rich a Mixture.
What are the limitations of a Float Type Carburetor?
Can only operate at Low Temperatures which results in:
- Incomplete Fuel Vaporization.
- Inadequate Fuel Flow from the Discharge Nozzle.
What are the two types of Carburetor Ice?
- Fuel Evaporation Ice
- Throttle Ice.
What is the long-term result of an Economizer Jet?
Two things
The Engine will not last long.
The Cylinder and Exhaust Temperatures are too High.
What would happen to the engine if the Ambient Vent were Blocked?
The Engine’s Fuel Mixture would run Lean.
The Floats are Leaking which is allowing the Fuel to Enter the Engine.
Operation would be affected how?
The Floats would Sink.
Why is a separate Idle Discharge Port needed?
The Main Circuit does no work at all when running at Idle.
What is the purpose of the Accelerator Pump?
Due to Venturi Lag, the traditional way to get fuel into the Engine is inadequate during acceleration.
The Accelerator Pump adds more fuel to make up for this inadequacy.
The mixture is Lean at Idle but runs noramally at High Power Cruise.
What is wrong?
An Induction Leak is present.
Air Bleeds are a necessity. Why?
They obliterate Surface Tension and start the Atomization Process.
What happens as the Throttle Valve Bushings Wear?
The Fuel Mixture Leans out due to an Air Leak being created.
Why Cut-Off the Fuel instead of Closing the Ignition Switch upon Shut-Down?
The Fuel Flow, or lack-thereof, shuts everything down if an issue were to occur.
Why use the Low Cruise setting during Best Economy?
Heat would otherwise be an issue.
What is the Best Power Mixture Ratio?
12.5 : 1 to 15.5 : 1
