NIFE ENGINES TEST PREPARATION
QUESTIONS WITH CORRECT
ANSWERS
components of propeller assembly - Answer-Blades: installed into the hub (barrel
assembly)
Hub: attached to the propeller shaft
Pitch change/dome assembly: the mechanism that changes the blade angle of the
propeller
reduction gear box (RGB) - Answer-converts high RPM/low torque from turbine and
convert to low RPM/high torque of propeller; Prevents the propeller blades from
reaching supersonic speeds;
Acts as a mounting pad for accessories
torque meter assembly - Answer-a set of shafts located between the gas generator and
RGB; used on some turboprop engines to transmit and measure the power output from
the gas generator to the RGB
The propeller assembly, RGB, along with the torque meter assembly may be connected
to the gas generator in what two possible configurations? - Answer-Attached to the front
of the compressor drive shaft
Attached to the free/power turbines (figure on p.68)
what percent RPM is a turboprop propeller maintained at during flight ops? - Answer-
100% RPM
how does a turboprop accelerate an air mass? (i.e. what size mass of air to what kind of
speed?) - Answer-accelerates a very large mass of air with its propeller to a moderate
speed
where does the non-propeller thrust come from in a turboprop? - Answer-exhaust gases
of gas generator
characteristics of a turboprop - Answer-Pros
Very high thrust at low speeds
Excellent take-off, slow speed, and low altitude characteristics
Superior for lifting heavy loads off short and medium runways
Lowest TSFC of any gas turbine (most fuel efficient)
Cons
Heavier and more complicated aircraft
, Limited speeds (approx. 400-450kts)
turboshaft engine - Answer-if the shaft of a free turbine or power turbine is used to drive
something other than an aircraft propeller, such as the rotor of a helicopter, the engine
is called a turboshaft
two basic sections of a turboshaft - Answer-Gas generator
free/power turbine section
what drives the power turbine in a turboshaft? - Answer-exhaust gases from gas
generator
where does the propulsive energy come from in a reciprocating engine? - Answer-from
the propeller driven by the rotation of the crankshaft
how can propellers be driven in a civilian aircraft with a reciprocating engine? - Answer-
by crankshaft directly or through a RGB first
governor - Answer-used to control the blade angle and propeller speed
Mechanically-driven accessories - Answer-Generators
Alternators
Pumps
Bleed-air driven accessories - Answer-Environmental systems
Cabin pressurization
Air Conditioning
Engine anti-icing
Tachometer (tells how fast engine is turning)
starting systems - Answer-Accelerate engine until turbine is producing enough power to
self-sustaining speed
starter - Answer-engages until engine attains self-accelerating speed
hot start - Answer-high temp (exceeds limits)
RPM normal
hung start - Answer-increasing high temp
RPM low
false start - Answer-no light off/non-start
temp normal
RPM low
QUESTIONS WITH CORRECT
ANSWERS
components of propeller assembly - Answer-Blades: installed into the hub (barrel
assembly)
Hub: attached to the propeller shaft
Pitch change/dome assembly: the mechanism that changes the blade angle of the
propeller
reduction gear box (RGB) - Answer-converts high RPM/low torque from turbine and
convert to low RPM/high torque of propeller; Prevents the propeller blades from
reaching supersonic speeds;
Acts as a mounting pad for accessories
torque meter assembly - Answer-a set of shafts located between the gas generator and
RGB; used on some turboprop engines to transmit and measure the power output from
the gas generator to the RGB
The propeller assembly, RGB, along with the torque meter assembly may be connected
to the gas generator in what two possible configurations? - Answer-Attached to the front
of the compressor drive shaft
Attached to the free/power turbines (figure on p.68)
what percent RPM is a turboprop propeller maintained at during flight ops? - Answer-
100% RPM
how does a turboprop accelerate an air mass? (i.e. what size mass of air to what kind of
speed?) - Answer-accelerates a very large mass of air with its propeller to a moderate
speed
where does the non-propeller thrust come from in a turboprop? - Answer-exhaust gases
of gas generator
characteristics of a turboprop - Answer-Pros
Very high thrust at low speeds
Excellent take-off, slow speed, and low altitude characteristics
Superior for lifting heavy loads off short and medium runways
Lowest TSFC of any gas turbine (most fuel efficient)
Cons
Heavier and more complicated aircraft
, Limited speeds (approx. 400-450kts)
turboshaft engine - Answer-if the shaft of a free turbine or power turbine is used to drive
something other than an aircraft propeller, such as the rotor of a helicopter, the engine
is called a turboshaft
two basic sections of a turboshaft - Answer-Gas generator
free/power turbine section
what drives the power turbine in a turboshaft? - Answer-exhaust gases from gas
generator
where does the propulsive energy come from in a reciprocating engine? - Answer-from
the propeller driven by the rotation of the crankshaft
how can propellers be driven in a civilian aircraft with a reciprocating engine? - Answer-
by crankshaft directly or through a RGB first
governor - Answer-used to control the blade angle and propeller speed
Mechanically-driven accessories - Answer-Generators
Alternators
Pumps
Bleed-air driven accessories - Answer-Environmental systems
Cabin pressurization
Air Conditioning
Engine anti-icing
Tachometer (tells how fast engine is turning)
starting systems - Answer-Accelerate engine until turbine is producing enough power to
self-sustaining speed
starter - Answer-engages until engine attains self-accelerating speed
hot start - Answer-high temp (exceeds limits)
RPM normal
hung start - Answer-increasing high temp
RPM low
false start - Answer-no light off/non-start
temp normal
RPM low
