Lesson 3 Powerplant and Propeller

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The Horizontally Opposed Engine
Motor Symbols
G geared
T turbocharged
S supercharged
I injected

Motor Symbols
Cylinder arrangement O opposed, I inline, R radial
L left turning engine
A acrobatic engine
V vertical helicopter

Four Stroke, Five Event Cycle
Firing order 1324
4 Stroke 5 Event Cycle

Engine Structure And Components
Connecting rods
Wrist pins
Piston, waffle piston

Engine Structure And Components
Push rods
Rocker arms
Vacuum pump
Pressure pump
Crankshaft And Camshaft

Basic Engine Parts
Engine Structure And Components
Oil pan, oil pump
Cooling fins, 3 locations
Cylinder head, cylinder barrel, and piston

Float Type Carburetor
B-19 Carburetor With Carb Heat Valve
B-19 Carburetor
B-19 Fuel Pump

Carburetor Ice
Carb ice
Carb ice can occur in high humidity between 20 and 70 degrees F
The vaporization of fuel causes lower temps inside the carb
Carburetor Ice Formation
Accumulation at low power settings is possible
Detection: a gradual loss of rpm or manifold pressure

Checking For Carb Ice
1. Pull on carb heat
2. Rpm reduce engine may run rough as ice melts
3. Slow increase in rpms
4. Take heat off, engine rpm will be higher than when you started

Keep in mind with carb heat on you are getting unfiltered air
Air density decreases
Mixture richens thus the drop in rpm
Engine performance decreases

Mixture Control
Mixture control prevent mixture from becoming too rich at high altitudes
Conserve fuel
Provide optimum power

Fuel Injection
Fuel Injection
Fuel injected into the intake valve
More even fuel distribution to the cylinders
No chance of carburetor ice (sometimes intake ice)
Usually more horsepower (better efficiency)
Hard to start when hot
Can be prone to vapor lock

Turbo And Superchargers
Turbo runs off exhaust discharge
Supers are belt or gear driven

Ignition System
Dual ignition system 2 Mags
Increased safety
More complete and even combustion
Totally independent of the electrical system

Pre-ignition And Detonation
Preignition ignition of fuel before the spark plug fires
Caused by something hot igniting fuel
Hot valves, pieces of carbon, hot spark plug

Detectible through small loss of power
Corrective action– try to cool it enrichen mixture to enhance cooling, reduce power, use cruise climb, level off, open cowl flaps

Sudden explosion inside cylinder
Caused by wrong grade fuel, Mags out of time
Up to 4000 psi inside cylinder
Will probably occur in all cylinders
Can’t be heard like in car

Detectable by unexplained high cylinder head temp
Whitish orange flame out exhaust
No power at high power settings
Corrective action– adjustment of engine controls

Use the right grade of fuel
For detonation during climb, lower the nose slightly to increase airspeed

May only occur in 1 or 2 cylinders
Corrective action– try to cool it enrichen mixture to enhance cooling, reduce power, use cruise climb, level off, open cowl flaps

Fuel Tanks
Hard cell

Fuel System Diagram
Cessna Fuel System Diagram

Usable Vs Unusable Fuel
59.8 gal, 7.8 unusable (52 usable) 2,4,5,59
2.6 unusable (57.2 usable) rest of the C-23’s and B-19’s

Fuel Grades
Jet A

Octane Grade And Substitution
Next higher grade
Fuel weights 6lbs per gal

We use mostly aeroshell 15-50
Oil pressure should show some indication by 30 seconds in summer and 60 seconds in winter

Oil Has 4 Purposes
1. Cooling, removes heat and reduces friction
2. Helps seal between cylinder wall and piston rings
3. Cleans
4. Prevents corrosion

2 or more small airfoils spun by the engine to create thrust
All propellers have a few things in common
Geometric twist
Tip rotates faster than the hub

Angle of attack becomes less the faster you go
This is why the engine speeds up the faster you go
As increase in altitude rpm increases because less drag caused by less dense air

Geometric pitch:
Distance a propeller would advance if it were rotated through a solid medium, (think Jello) doesn’t account for slippage

Effective pitch:
The actual distance a propeller moves through the air in one revolution, accounts for slippage

Propeller (Fixed Pitch)
Throttle controls rpm
Simple to operate
Lower cost
Less weight
Less expensive to overhaul

Propeller (Constant Speed Or Variable Pitch)
Constant speed prop controlled by governor
Explain governor
Pilot can control the pitch from the cockpit prop control lever

Propeller (Constant Speed Or Variable Pitch)
Pitch on bonanza 12.5 to 34º
Longer engine life
Less pilot fatigue
More efficient operation
Can reduce drag in emergency glide configuration

Engine controls for a constant speed prop engine
Mixture control
Same as that for fixed pitch prop engine
Leaning the engine Rule of thumb whenever power is 75% or less or above 5000 feet

Leaning Procedures
B-19 lean until peak rpm (engine may run rough if you go too lean) enrichen back to peak rpm then a little more
C-23 use peak egt then enrichen for 50 degree drop
F-33A use peak egt then enrichen for 100 degree drop

Propeller Control
Hooked to speeder spring in governor
Control rpm by reference to tachometer

Throttle Control
Manifold pressure gauge measures pressure in the intake manifold in inches of mercury
Control power by reference to this instrument

Electrical System

Electrical System
Circuit breakers
Overvoltage relay
Buss Items
Pitot heat
Landing light
Nav lights
Cockpit lighting
Boost pump
Stall horn
Hobbs meter
Fuel gauges
Turn coordinator

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