AMT 212 WEEK 2 PPT 2 Flashcards
Factors affecting engine power
Anything that adversely impacts the quality of the atmosphere affects
the power output of the powerplant.
Nature’s variables to engine performance
Ambient Pressure, Temperature, Humidity
Significant increase in altitude generate notable reduction in engine
performance.
* Every airplane or aircraft has a “service ceiling” which dictates the
highest altitude the aircraft can achieve.
* As the aircraft increases altitude barometric pressure decreases.
* The main thing behind the reduction of the aircraft’s ability to
continue to climb in aggressively is due to the reduction of barometric
pressure as the aircraft increases altitude.
Ambient Pressure
What happens to the engine when barometric pressure decreases?
When the engine is in the intake stroke, less oxygen is ingested by the
cylinder at high altitude than when the engine is operating near sea
level (14.7 PSI). The net result is a reduction of horsepower developed
by the powerplant.
A key variable involved in determining
aircraft performance for any given day is
temperature.
* Both aircraft performance and powerplant
output are affected by temperature. In
terms of aircraft performance, the lift
generated by the wings is proportional to
the density of the air. On hot, humid days,
the takeoff roll is notably longer than on
cold, dry days. The same parallel is true
concerning the output of the powerplant.
Temperature
When ___ is high, the performance of the powerplant and airfoils are adversely affected.
High ___ means less oxygen and
will alter the combustion of the fuel and
air mixture.
High _____ will result to less lift and
less thrust.
Humidity
Mechanical Issues Affecting engine Performance
- IGNITION PROBLEMS
- INTERNAL MAGNETO TIMING
- MAGNETO TO ENGINE TIMING
- FUEL METERING ISSUES
- EXHAUST SYSTEM
- COMPRESSION
- FUEL AND AIR MIXTURES
- PRE-IGNITION
- DETONATION
The ____ system of a
typical reciprocating aircraft
powerplant is supplied using
two magnetos.
Ignition problems
The spark plugs need
thousands of volts to
generate a hot spark that
bridges the electrodes. Any
defect that reduces the
magnitude of the spark may
result in a reduction of
engine power.
Ignition problems
Incorrect E-gap timing reduces
the intensity of the spark
delivered to the spark plugs,
when the spark occurs during
the compression stroke also
impacts the performance of
the engine.
Internal Magneto Timing
A retarded spark results in a
fuel/air charge that continues
to burn after the piston
reaches and passes TDC.
Internal Magneto Timing
occurs when
the cylinder experiences
an uncontrolled burning
of fuel and air charge
upon ignition.
Detonation
Low octane fuel in an
engine that requires
high octane gasoline will
result to detonation.
Detonation
