Aircraft Systems Part 1/2 Flashcards
Name 10 aircraft systems
Engine Propeller Induction Ignition Fuel Lubrication Cooling Electrical Landing Gear Environmental Control
Most small aircraft are designed with what kind of engine?
Reciprocating engine (pistons move back and forth)
Name the two primary reciprocating engine designs (not types)
- Spark ignition
- Compression ignition
Name the most popular reciprocating engine used on smaller aircraft
Opposed-Type engine (can be spark or compression ignition)
Most common engine type used in general aviation
Spark 4 stroke engine
Continuous operation of the engine depends on what auxiliary systems
- Induction
- Ignition
- Fuel
- Oil
- Cooling
- Exhaust
A propeller is a:
Rotating Airfoil
The amount of thrust a propeller produces depends on:
- Shape of the airfoil
- Angle of attack of the propeller blade
- Revolutions per minute
Why is a propeller twisted?
To produce uniform lift. There is a difference in speed through out the blade.
Name two types of propellers
Fixed pitch vs adjustable pitch propellers
Name two types of fixed pitch propellers & describe them
Climb (less drag, higher rpm, more horsepower, decreased performance for cruising flight)
cruise propellers (more drag, less rpm, less horsepower, increased efficiency in cruising flight)
Name the indicator of engine power & how is it calibrated?
Tachometer - calibrated in hundreds of rpm
What does a tachometer indicate
engine power via engine and propeller rpm
What is the green arch on a tachometer?
maximum continuous operating rpm
How is rpm regulated?
Throttle - controls the fuel/airflow through the engine
What does engine power output depend on?
Air density (decreases as altitude increases)
What does a decrease in air density result in? When?
Decreased power output of the engine. As you increase in altitude
How to you maintain the same rpm as you gain altitude?
Position of throttle must be changed
Describe a constant-speed propeller
- Pitch automatically varied during flight by a governor
- Constant rpm despite varying air loads
- Most common type of adjustable pitch propeller
- more efficient
Two controls for adjustable propeller aircraft:
- Throttle (controls power output)
- Propeller control (regulates engine RPM)
On an aircraft with a constant speed propeller, power output is controlled by:
The throttle and indicated by a manifold pressure gauge
What does a manifold pressure gauge measure?
Measures absolute pressure of fuel-air inside intake manifold
What does an induction system do?
Brings in air from the outside, mixes it with fuel and delivers the fuel-air mixture to the cylinder where the combustion occurs
Name two types of induction systems
Carburetor system & fuel injection system
What are two types of carburetor systems
Float type (most common) Pressure type (uses fuel pump)
Name disadvantages of float type carburetors
- Disrupted by abrupt maneuvers
- Low pressure fuel discharge causes incomplete vaporization & inhibits injection systems
- icing tendency
When does carbon buildup occur?
As altitude increases, air density decreases. Since density of fuel remains the same, it creates a progressively richer mixture that can result in engine roughness & loss of power. Rich mixture lowers the temp inside the cylinder, inhibiting complete combustion of the fuel.
During descent, mixture must be:
enriched to avoid an excessively lean mixture
Overly lean mixture can cause:
Detonation & rough engine operation, overheating, loss of power, damage engine
Best way to maintain proper mixture
Monitor engine temperature. An exhaust gas temperature gauge can aid proper mixture.
What is carb ice caused by?
A sharp decrease in temp in the carb, due to vaporization of the fuel and the low pressure at the Venturi
Ice is most likely to occur when temperature & humidity is:
Below 70degF or 21degC & relative humidity is above 80%
First indication of icing in an aircraft with a fixed pitch propeller
Decrease in engine RPM
First indication of icing in an aircraft with a constant speed propeller
Drop in manifold pressure but no reduction in rpm
Ice is particularly dangerous during:
low power descents where engine temp is low & ice may build unnoticed until power is increased
Carb heat causes a decrease in engine power, why?
Heated air is less dense than outside air that had been entering the engine, thus the mixture is enriched
Name 6 basic components of a fuel injection system
- Engine driven fuel pump
- Fuel/air control unit
- Fuel manifold valve
- Fuel distributor
- Discharge nozzles
- Auxiliary fuel pump
- Fuel pressure/flow indicators
What is impact icing?
Ice forms on exterior of the aircraft & blocks openings such as air intake
Name advantages of fuel injection
- Reduction in evaporative icing
- Better fuel flow
- Faster throttle response
- Precise control of mixture
- Better fuel distribution
- Easier cold weather starts
Disadvantages of fuel injection
- Difficulty in starting hot engines
- Vapor lock during ground ops on hot days
- Problems restarting of fuel-starved engine
