Aircraft Systems 3 Flashcards
Exceeding the max. manifold pressure will cause damage to
Cylinder Components and possible cause engine failure
Extremely high temperature in reciprocating engine cause:
Detonation
Spark plug fouling is result off
Excessive carbon buildup
Detonation is likely to occur when
the mixture is too lean
Preignition causes
loss of power
You are reading that the oil temperature is high and oil pressure is low. Why?
Oil is below minimum oil needed
What happens when a pilot operate the manifold pressure lever in constant-airspeed propeller?
When pilot increase throttle, the governor increase e propeller pitch to maintain constant RPM
An excessively rich mixture will cause the engine to run rough. This is due to excess fuel
not being burned completely and fouling the spark plugs
What is detonation?
Uncontrolled, explosive ignition of
the fuel-air mixture.
What is the cause of detonation?
excessive temperatures and pressure. Can lead to piston failure.
Common operational causes of detonation are
- Use of a lower fuel grade than that specified.
- Operation of the engine with extremely high manifold pressures in conjunction with low rpm
- Operation of the engine at high power settings with an excessively lean mixture
When does pre-ignition occur?
the fuel-air mixture ignites prior to the engine’s normal ignition event
What is the cause of preignition?
1) residual hot spot in the combustion chamber, often created by a small carbon deposit on a spark
plug,
2) a cracked spark plug insulator,
What does pre-ignition cause?
engine to lose power and produces high operating temperature
What are the differences of mechanical components of spark ignition and the compression ignition engine?
Same.
1) cylindrical combustion chambers and
2)
What is the main difference between speak ignition and compression ignition?
spark ignition and compression ignition is the process of igniting the fuel.
How does spark ignites?
Spark ignition engines use a spark plug to ignite a pre-mixed fuel-air mixture.
How does compression ignition engine is ignited?
first compresses the air in the cylinder, raising its temperature to a degree necessary for automatic ignition when
fuel is injected into the cylinder.
FULL RICH position is calibrated at what level of flight?
calibrated at sea-level air pressu
Carbon buildup occurs because
the rich mixture lowers the temperature
inside the cylinder, inhibiting complete combustion of the fuel.
Why during a descent from high altitude, the fuel-air mixture must be enriched?
it may become too lean
Propeller
efficiency varies from ____ to ____ percent, depending on how much the propeller “ ______.”
50
87
SLIPS
What is a propeller slip?
difference
between the geometric pitch of the propeller and its effective pitch
Why a propeller is twisted?
1) permits the propeller to operate with a relatively constant AOA along its length when in cruising flight.
2) Keeps thrust more nearly equalized along this length.
How does Counterweight
detuning can occur?
1) from rapid opening and closing of the throttle,
2) excessive speed,
3) excessive power,
4) operating at high
engine speed and low manifold pressure, and improper feathering procedures.
Fuel-air ratios between these limits produce varying amounts of output power and the maximum power output generally occurs at fuel-air ratios of approximately _________
0.07 to 0.08.
What is the “best power” range?
range of fuelair
ratios which produces maximum power for a given airflow is termed the “best power” range
What is the “best economy” range?
lower range
of fuel-air ratios, a maximum of power per fuel-air ratio is obtained and this the “best economy” range.
What is the fuel air ratio that best economy occur?
The best
economy range generally occurs between fuel-air ratios of 0.05 and 0.07.
Turbine engine thrust varies directly with air ________
density.
Check oil temperature periodically during flight especially when operating in _____ ambient air temperature
high or low
High oil temperature indications may signal
1) plugged oil line,
2) a low oil quantity, 3) a blocked oil cooler, or
4) a defective
temperature gauge.
Low oil temperature indications may signal improper oil viscosity during ________ operations
Cold weather operations
Exhaust gases contain large amounts of __________, which is odorless and c
carbon monoxide
color and smell of carbon monoxide?
odorless and colorless
Why the constant speed propeller sets up a low propeller blade angle (pitch)?
the low
blade angle keeps the angle of attack, with respect to
the relative wind, small and efficient at the low speed.
Why the constant speed propeller sets up a low propeller blade angle (pitch)?
1) the low blade angle keeps the angle of attack, with respect to
the relative wind, small and efficient at the low speed.
2) it allows the propeller to “slice it
thin” and handle a smaller mass of air per revolution.
This light load allows the engine to tum at maximum
r.p.m. and develop maximum power.
Why do we need to pay special attention to engine oil breather?
When crankcase vapors cool, they may condense in the breather line and subsequently freeze it closed.
The constant-speed propeller keeps the blade angle
adjusted for _____________for most conditions
of flight.
maximum efficiency
what is the purpose of governor on constant speed propeller?
senses the speed of an aircraft engine and changes the propeller blade angle to maintain a selected RPM regardless of the operational conditions of the aircraft.
For maximum takeoff power, the propeller control is moved __________ to the low pitch/high r.p.m. position
all the way
forward
How do you reduce the power of climb or cruise manifold pressure reduced with?
throttle
How can you reduce the engine RPM?
moving the propeller control back toward the high pitch/low r.p.m. position until the desired r.p.m. is
observed on the tachometer.
