Final Flashcards
What 2 things make up the definition of Airworthy?
- A/c is in condition for SAFE operation
2. A/c has all REQUIRED INSPECTIONS and they have been properly logged
What is 91.7 in the FARAIM
Rule and limitations of PILOTS
What is Critical Pressure?
- Ignition through compression/point of combustion
- Higher pressure and temp. aid in reaching Critical Pressure
What is the complete combustion ratio?
Stochiometric - when ALL chemical elements are used up
15 lbs air : 1 lbs fuel
What does the Camshaft do? What drives it?
- Operates valve mechanism of opposed engines
- DRIVEN by CRANKshaft
- Operates at 1/2 the speed because gear is larger
What part of the engine is subject to the most force?
CRANKSHAFT!
What does the Crankshaft do?
Transforms rotary motion of piston and rod to rotation of the propeller (uses counterweights)
What are the 2 types of engine instruments?
- Power (pressure gauges)
2. Condition (temp gauges)
6 things oil does for us?
- Cools
- Cleans
- Lubricates
- Actuates
- Cushions
- Seals
What does a prop. Governor do?
Controls SPEED of prop
What is one important ratio to know about the stalling/critical AOA of the prop (think about the graph)
Forward Velocity/Rotational Velocity
Graph: lift on vertical axis, AOA on horizontal axis
What does the THROTTLE control?
Manifold Pressure!
What does the PROPELLER control?
RPM!
What kind of hydraulic fluid do we have in our C172s?
MIL-H 5606
It is Red!
If your alternator fails, will your engine fail? Why?
No, the electrical system and engine are INDEPENDENT SYSTEMS!
What 3 things affect the output of an alternator?
- # of conductors
- RPM
- Strength of the magnetic field
What kind of current do SLIP rings produce?
Slip rings produce AC current
What are the 2 types of electricity?
- Static (useless)
2. Current (alternating and direct)
AC Generators have ____ rings.
SLIP rings
DC generators have ____ rings
SPLIT rings
Generators have ____ mags, and a ____ conductor/coil
- Stationary Mags
2. Rotating conductor/coil
How many E are in 1 Coulomb?
6.28 x 10 to the 18th power
1 HP = ____ ft/lbs OR ____ watts
33,000 ft/lbs per min OR 746 watts
What are the 6 ways to produce electricity?
- Friction
- Heat (thermocoupling)
- Light (light is energy)
- Pressure
- Chemical reaction (imbalance of electrons)
- Magnetism
What is thermocoupling?
When 2 different metals are connected at different temps, allowing E to cross
What is a battery?
An energy storage device?
What is a TRU?
Trans-rectifying unit
- Converts AC to DC
How are Superchargers driven? When does compression occur?
- Driven directly by engine power
- Compresses air/fuel AFTER is leaves the carb
How are Turbochargers driven? When does compression occur?
- Driven by hot, high velocity EXHAUST GASES expelled from engine
- Compresses air BEFORE its mixed with fuel from carb
What are the 3 main parts of a Trubocharger?
- Compressor Assembly
- Exhaust Gas Turbine Assembly
- Pup and Bearing Casing
What is a Wastegate? What 2 systems are used to regulate the wastegate?
- Regulates amount of exhaust gas directed to turbine
1. Differential Pressure Controller
2. Fuel metering
How does an Engine Starter work?
Induces currents that create a magnetic field
What a Generator do?
Creates current
What does the Alternator Belt do?
Takes current and turn to transfer energy into mechanical work
What is manifold pressure?
Measure of intake downstream of the throttle valve
What is Overboost?
Max. manifold pressure is exceeded
What is pour point?
Lowest temp at which oil can flow still
The number associated with aviation OIL is an approximation of that oil’s ______
Viscosity
What are the 2 types of lubrication systems?
- Wet-Sump (oil kept under the engine)
2. Dry-Sump (oil kept in a separate reservoir)
4 disadvantages of a wet-sump lubrication system?
- Supply limited to pan capacity
- Cooling is more difficult
- Subject to higher operating temps of the engine
- Inverted flight = flooded engine
Disadvantage of a dry-sump lubrication system?
MORE PARTS/UNITS!
What 4 things does Critical Pressure effect/determine?
- Compression Ratio (higher is ideal)
- Cylinder pressure (higher is ideal)
- Power output and fuel consumption
- Octane Rating
What does an oil analysis look for?
- Compression
2. METAL
What are the 3 ways to wear out oil?
- Thermal cycling
- Shear
- Frequency vibration
Do warmer climates need thicker or thinner oil to operate?
Warmer = THICKER! (bc weighs more)
What are the 3 thermal efficiencies?
- Volumetric
- Chemical
- Mechanical
What is volatility?
How much vapor a substance gives off in relations to it’s temperature!
When does Detonation occur?
With an excessively LEAN mixture
Why is it important to know about the fuel system?
So that we can troubleshoot in emergencies
What is a BTU? What is it for Avgas?
British Thermal Unit
- Amount of heat energy is needed to raise 1 lb of H2O by 1 degree F
- Avgas is 20,000 BTU per pound
What does Octane do for us?
Helps reduce all energy in the fuel, must be completely burned!
Why use fuel additives?
- Anti-detonation characteristics while allowing engine to develop more power
What is a Gascolator?
- Fuel filter
What is the function of the fuel metering system? What drives it?
- Mix fuel with weight of air and uniformly distribute it to all cylinders
- Driven by the FUEL METERING FORCE (pressure differential between venturi and float chamber)
What are the 2 basic types of batteries?
- Primary (non-rechargeable)
2. Secondary (rechargeable)
What is Rated Capacity?
The batteries ability to perform when it is NEW
3 ways to manipulate VOLTAGE?
- # of magnets
- Strength of magnets
- Speed of movement
What is the function of Diodes in an alternator?
1-way check valve! Make sure E are flowing in 1 direction.
What is the difference between a Relay and a Solenoid?
Relay - used in SMALLER circuits
Solenoid - used in HIGHER CURRENT circuits
What is TCDS?
Type Cert Data Sheet
What part of the FAR’s is a/c Airworthiness Standards?
Part 23
Name 2 kinds of house power and describe them.
Brake Horsepower - developed from engine’s rotating shaft
Thrust Horsepower - converted BHP by propeller. % prop efficiency.
What does the FAA form 337 tell you about?
Major repair and alteration
How many revolutions of the crankshaft are there per cycle?
2 revolutions = 4 strokes (1 cycle)
What engine component is geared to the driveshaft and is used to open valves at the proper time?
- Rocker arm/valve spring
- Cam lobes on camshaft that rotate and push the rob up to open
A rotating propeller is acted upon by what 4 forces?
- Centrifugal (outward)
- Thrust Bending (forward)
- Torque (yawing)
- Aerodynamic Twisting (of prop. blade)
Describe a Fixed-Pitch Prop.
- Built for max. efficiency at ONE set of conditions
- Efficiency at low and high pitches varies
Describe a Constant-Speed Prop.
- Have Governors that change the prop. pitch with conditions to achieve max. efficiency
- Efficiency at low and high pitches is in theory going to be the same
What is the purpose of a Reverse-Pitch Prop?
- Control prop to produce negative thrust at low air speeds
- Aerodynamic braking to reduce ground roll after landing
What is the purpose of a Feathering Prop?
- Control prop to reduce drag during engine failure conditions
- Produce a minimum windmilling effect
Why do prop blades vary in pitch along the blade?
Attempt to reduce aerodynamic twisting
Describe aerodynamic twisting.
Thrust along with unbalanced forces acting on a prop make blade want to twist about its longitudinal axis
When are the blade angle and blade AOA the same?
When not in motion!
What is prop slip?
The difference between Geometric Pitch (THEORETICAL provance of prop in 1 rev. with NO slip) and Effective Pitch (ACTUAL advance of prop in 1 revolution WITH slip)
Where does Relative Wind hit the prop blade?
RW hits the back of the prop blade ALWAYS! Angle become smaller as forward velocity increases
