Class Two - Engines, Electrical Systems, Flight Instruments Flashcards
What are the four parts of a four stroke engine
- Intake stroke (fuel)
- Compression stroke
- Power stroke
- Exhaust stroke
FAA question: What is one purpose for using reciprocating engines?
They are relatively simple and inexpensive to operate.
Why do aircrafts have dual ignition systems (2 spark plugs per cylinder)?
- Efficiency - lighting a fire from multiple sides crease a smoother, more even spreading flame allowing a more “uniform heat distribution”
- Increases safety (these must work at all times)
Magnetos
Spark Generators! A self contained source of electrical energy so if the aircraft lost its electrical power, the engine will continue to run.
How do magnetos work?
They contain spinnable magnets, housed in a metal case, that generate the electrical sparks for the spark plug.
What is a run up test - MAG drops?
Selecting the right or left magneto deactivates the other mag by grounding it to the airframe. Absence of a mag drop can indicate that a mag may not be grounded. Prop safety.
FAA Question: One purpose of the dual ignition system on an aircraft engine is to provide for:
Uniform heat distribution
FAA Question: An electrical system failure (battery and alternator) occurs during flight. In this situation, what would you experience?
Avionics equipment failure (radio).
What does a carburetor do?
To mix a perfect amount of air and fuel together to send to each one of the cylinders
Carburetor Idling System
When the throttle is pulled back all the way, the butterfly valve closes and power is reduced. The engine continues to run at a lower power because the idle mixture screw on the side allows a small amount of fuel to sneak by the throttle (butterfly) valve.
Carburetor’s Accelerator Pump
When throttle is opened quickly (pushed forward and pushes plunger down), the accelerator pump squirts a small jet of fuel into the carburetor’s throat to compensate of the sudden inrush of air into the engine, preventing engine stammer or hesitation.
FAA Question: The operating principle of float-type carburetors is based on what?
The difference in air pressure at the Venturi’s throat and the air inlet.
Carburetor Butterfly Value
As power is added, the butterfly valve opens and closed when power is reduced.
Carburetor Ice
Due to atomization and evaporation of fuel, any moisture present can freeze. CAN happen at any temperature, most likely with outside temperatures between 20-70 degrees F. The temp will drop as much as 70 degree F within a carburetor’s throat.
What are the two form of carburetor ice?
- Throttle ice: forms on the backside and downstream of throttle valve
- Fuel ice: forms along throat of carb and upstream of throttle valve.
Throttle Ice
forms on the rear of throttle valve and mostly likely to occur when the throttle valve is partially closed. Carburetors break up fuel into millions of tiny, atom like droplets and mix them with the air, and this atomization cools the cylinder
Impact Ice
Occurs when visible moisture is present. Moisture can freeze the induction systems air filter and restrict the incoming air, and may also occur during freezing rain.
Carb Heat
Pulling unfiltered air from the heat shroud around the exhaust manifold to prevent or remove impact ice.
How to detect carb ice
- RPM decreasing (you suspect carb ice)
- Apply full carburetor heat (RPM decreases further)
- As ice melts the RMP increases (it rises then stops)
d. Carb heat is then turned off (RMP rises again)
FAA test question: which condition is most favorable to the development of carburetor icing?
Temperature between 20 and 70 degrees F and high humidity
FAA test question: If an aircraft is equipped with a fixed pitch propeller in a float type carburetor, the first indication of carburetor ice would most likely be:
Loss of RPM
Mixture Control - The Red Knob
Allows you to keep your aircraft operating with the proper fuel-air ratio as air density changes with altitude.
1. Pulling it out towards you = leaning
2. Pushing it away from you = rich
How do you accomplish leaning fuel?
Leaning is accomplished by restricting the flow of fuel through the main metering jet (idle cutoff if you pull it all the way out)
Fuel air mixture
Increase in altitude, air becomes thinner and doesn’t weigh as much for a given volume. To maintain the same fuel-air ratio at higher altitudes, we must manually adjust the amount of gas leaving the carburetor.
When do you lean the engine?
- Operating at 75% power or less
- Above 3.000 MSL (mean sea level)
- Anytime to increase you GPH (fuel efficiency)
Adjusting fuel air mixture: Tachometer
- RPM increasing (mixture is leaned)
- RPM increasing (mixture is further leaned)
- RPM at peak (mixture leaned to peak RPM)
- RPM decreasing (mixture is excessively leaned)
Adjusting fuel air mixture: EGT (Exhaust gas temperature gauge system)
- Mixture too rich: causes high fuel consumption, causes engine roughness, spark plugs become fouled due to unburned fuel residue buildup
- Mixture too lean: less power is produced, increases piston/cylinder temperature (high cylinder temps lead to detonation!)
Detonation
abnormal power stroke where detonation causes sudden explosion of gas
FAA test question: Detonation occurs in a reciprocating aircraft engine when:
the unburned charge in the cylinders explodes instead of burning normally
Pre ignition
Hotspots in the combustion chamber ignite the fuel-air mixture in advance of normal ignition
Aircraft exhaust systems
Aircraft exhaust is expelled from the cylinder and flows over the hot exhaust manifold, which can be used for cabin air eat, carburetor heat and and sometime turbochargers. Cracks in the manifold can cause carbon monoxide entering the cabin.
High Wing Fuel System
typical gravity fed fuel system
Low Wing Fuel System
most have electric fuel pump in addition to an engine driven fuel pump
Fuel Sumps
Fuel tanks have sump drains at the lowest part of the tank and pilots make sure to drain the sumps during each preflight and fill up to check for both water and containments and fuel color. Engines should not ingest any contaminants such as water.
Fuel Vents
prevent a vacuum from forming when the fuel pump draws fuel away from the tanks, and allows fuel expansion on hot days. Ensure that the fuel vents are unobstructed during pre flight
Oil System
- Oil helps to regulate temperatures by carrying heat away from the engine to keep engine temps within limits
- Oil created a thin film that clings to the metal surfaces allowing them to slide over each other with minimal contact (lubrication)
Low Oil Pressure
Serious issue that affects the engine’s internal cooling capability
High Oil Temp
Results from not enough oil and can be caused by excessive engine temp which can cause excessive oil consumption, loss of power and detonation. Lower the nose, level off or descend at a lower power setting
FAA test question: excessively high engine temperatures will:
cause loss of power, excessive oil consumption and possible permanent internal engine damage.
Fixed Pitch Propeller
- One lever (throttle) controls both power and propeller blade RPM (Power = RPM)
- Propellers have their pitch fixed (angle of attack) during their creation and are set in stone
- Represents a comprised between the best AOA for a climb and the best angle for a cruise
Constant speed propeller
- Separate controls for power and RPM
- Movement of the pro control changes the propeller pitch (AOA)
- Allows pilots to choose the most efficient prop blade angle for the climb, en route and decent.
FAA test question: What is the advantage of a constant speed propeller?
Permits the pilot to select the blade angle for the most efficient performance.
Fuel Injected System Fundamentals
fuel is directly metered and distributed without the use of a carburetor (fuel/air control unit replaces it). A fuel control unit regulates the mixture delivered to the fuel manifold unit.
Pros of a Fuel Injected System
- Improve control of the fuel air ratio
- More uniform delivery of the fuel air mixture to each cylinder
- Increased engine efficiency
- Freedom from vaporization ice or fuel ice
- Instant acceleration of engine without a tendency to hesitate
Cons of a Fuel Injected System
- Contamination by dirt and water can more easily affect fuel injected engines due to small orifices of injector nozzles
- Difficult starting engines on hot days due to vapor lock
- Any surplus fuel could be routed to one tank and cause a fuel imbalance of the pile is not familiar with the fuel system
How to handle a high or low voltage warning light
- Turn avionics master switch OFF
- Reset two circuit breakers if popped (ALT CB and ALT FIELD CB)
- Cycle master switch (turning it on and off and on again)
Pitot Static System
Controls airspeed indicator, vertical speed indicator and altimeter. Static port measures outside air pressure, shared with all three instruments
Airspeed indicator (ASI)
High velocity air rushes into the pitot tube and applies pressure within the bellows. A static source allows non-moving (static) air to enter the airspeed container. The difference between the impact air press thru the pitot and the static air pressure.
Vso
Beginning of the white arc on an ASI which is the power off stalling speed with gear and full flaps extended (velocity speed 0)
Vs1
Beginning of the green arc on an ASI which is the power off stalling speed with gear and full flaps retracted
Vfe
The high speed end of the white arc on the ASI which is the maximum flap operating speed (velocity flap extension speed)
Green arc on the ASI
Normal operating range
Vno
The high speed end of the green arc on the ASI which is the maximum structural cruising speed
Yellow arc on ASI
Caution range
Vne
Red line on the ASI which is the never to be exceeded speed
V, VA, VLO, VLE
V = velocity, VA = maneuvering speed, VLO = landing operating speed, VLE = max. landing gear extended speed
Indicated Airspeed (IAS)
the uncorrected reading obtained from the airspeed indicator
Calibrated Airspeed (CAS)
indicated airspeed corrected for installation errors
True airspeed (TAS)
calibrated airspeed corrected for temperature and pressure variations (1,000 ft altitude increase is about 2% increase in true airspeed).
True airspeed vs. Indicated airspeed
is more important at high altitude airports where the air is less dense. Landing and take off distances can be increased.
How do you calculate tailwind speed?
Take TAS (115 kts for example) and ground speed (GS is 125 kts) and the difference of 10 kts if the tailwind
FAA test question if the pitot tube and outside static vents become clogged, which instruments would be affected?
The altimeter, airspeed indicator, and vertical speed indicator.
Standard Atmosphere and Temperature
1” of Mercury = 1,000’ (example; increasing the setting dial from 29.15 to 29.85 = 700’ increase). Prior o take off, the altimeter should be set to the current local altimeter setting (Standard temp & pressure are 29.92” HG and 15 degrees C)
Density Altitude
Pressure altitude corrected for nonstandard temperature and pressure. As an aircraft climbs, the ability of the engine to produce power decreases due to the reduced air density
True Altitude
provides height above sea level (MSL) mean sea level
Absolute Altitude
height above the ground (AGL) above ground level
Pressure Altitude
altitude indicated whenever the Kholsman is set to 29.92”
Altimeter
measures height above sea level, not above ground level. It works by measuring static air pressure (air’s weight)
FAA test question: to determine pressure altitude prior to takeoff, the altimeter should be set to
29.92” Hg and the altimeter indication noted
Vacuum pump
sucks air over the attitude indicator and the heading indicator. Air enters these instruments from the air filter located either on the engine side of the firewall or inside cockpit
Turn Coordinator
Made up of an inclinometer consisting of a black ball suspended in a liquid-filled glass tube and a rate of turn needle that rotates right and left.
Magnetic Compass Errors
V- Variation
D- Deviation
M- Magnetic Dip
O- Oscillation
N- Northernly Turning Errors
A- Acceleration/Deceleration Errors
Magnetic Deviation
Airplanes have iron and steel components which are affected by the earth’s magnetic field, and because it contains wiring which create a magnetic field within the plane, the plane’s magnetic compass develops an error which varies with aircraft heading.
Magnetic dip
the magnetic compass needle follows the slope of the Earth’s magnetic field. Where the slope dips downward (near the poles) the compass needle also dips
Acceleration and deceleration errors
A- Accelerate
N- North
D- Decelerate
S- South
Northerly turning errors
U- Undershoot
N- North
O- Overshoot
S- South
