Fuel Metering & Induction Systems Flashcards
Define stoichiometric mixture.
The fuel-air mixture that, when burned, leaves no uncombined oxygen nor any free carbon. It releases the maximum amount of heat and produces the highest EGT.
The stoichiometric air-to-fuel ratio is ________.
15:1
The amount of pressure that must be exerted on a liquid to keep it from vaporizing is the ______ _______ _______.
Reid Vapor Pressure.
RVP
AV Gas is required to have an RVP (Reid vapor pressure) of _______ psi.
5.5 - 7 psi.
If RVP is too high, what happens to the fuel?
Vaporizes too easily.
An air-fuel mixture of 12:1 is said to be a _____ _______.
Rich mixture
An air-fuel mixture of 17:1 is said to be a _____ _______.
Lean mixture.
_______ ______ is added to Avgas to reduce the likelihood of detonations.
Tetraethyl lead.
Name the types of carburetors.
1) Float type
2) Pressure type
All carburetors use ______________ to meter the correct amount of fuel to the engine.
The volume of air
Name the mixture control positions.
1) Full Rich
2) Idle Cutoff
3) Best Power
4) Best Economy
Name the metering systems.
1) Main Metering
2) Idling
3) Mixture Control
4) Accelerating System
5) Power Enrichment / Economizer
T\F
The main metering system supplies the correct amount of fuel for idle speeds.
False.
All speeds above idle
The part that releases atomized fuel into the Venturi of a carburetor:
Main discharge nozzle
The atomization of the fuel is made possible by what?
The Air Bleed System
The atomization of fuel promotes ______ _________.
Fuel vaporization
The ___________ ensures that when the throttle valve is closed, fuel is still supplied to the engine.
Idling system.
At ground idle, a rich mixture can do what to the engine?
Provide cooling.
The types of mixture control systems are:
1) Variable Orifice
2) Back Suction
3) Automatic Mixture Control
The system that regulates the ratio of fuel to air supplied to the engine at speeds above idle:
Mixture Control
The type of mixture control system that physically limits the volume of fuel:
Variable Orifice
The type of Mixture Control system that limits fuel volume by controlling the pressure difference between the float chamber and Venturi:
Back Suction
The automatic mixture control uses a ______ that will actuate the mixture control.
Bellows.
At higher altitudes, the bellows will do what?
Expand
When the bellows retracts what happens to the fuel-air mixture?
Enriches
T/F
Automatic mixture controls are found on float carburetors.
False
Automatic mixture controls are found on _______ and _______.
Pressure carburetors
Fuel injection systems
Used to momentarily increase fuel to the engine during rapid throttle movements:
Acceleration system
The types of acceleration systems:
1) Acceleration Well
2) Acceleration Pump
Used during high power to aid in engine cooling:
Power Enrichment System
Types of power enrichment systems:
1) Needle Type
2) Air Bleed Type
3) Back Suction Type
The disadvantages of carbureted engines:
1) Carburetor Ice
2) Fuel flow interruption during abrupt flight maneuvers.
3) Incomplete Fuel Evaporation
The types of carburetor ice:
1) Throttle ice
2) Fuel evaporation ice
The band of flammability range is _________.
18:1 to 8:1
The two adjustments for setting idling conditions of an engine:
1) The closed position of the throttle. (Affects RPM)
2) The amount of fuel-air mixture discharged. (Idle mixture adjustment)
A condition in the rigging of an aircraft engine control in which the stop at the engine is reached before the stop in the cockpit.
Springback
Two instruments to observe when performing an idle adjustment:
1) Tachometer (RPM)
2) MAP
Primary components of the main metering system:
1) Throttle Valve
2) Venturi
3) Main Discharge Nozzle
4) Main Metering Jet
Name the types of variable orifice mixture controls.
1) Needle valve
2) Step-cut rotary valve
