NIFE ENGINES EXAM QUESTIONS
WITH COMPLETE SOLUTIONS
Compressor Stall Recovery - Answer- Reduce aircraft attitude: reduce inlet AOA
Slowly retard the PCL to just below stall threshold: allows engine to catch up with inlet
air
Engage bleed valves: increase airflow
Slowly advance PCL when engine indications return to normal
Creep - Answer- Abnormal elongation of turbine blades due to overheating over long
periods of time, can result in permanent deformation.
Fir Tree - Answer- How turbine blades are attached (not welded) to allow for repeated
heating and cooling throughout life of engine.
Purpose of Exhaust Section - Answer- To direct the flow of hot gases rearward, causing
a high exit velocity of the gases while preventing turbulence
Exhaust Nozzle Types - Answer- Convergent (subsonic)
Convergent-Divergent (super sonic)
Parts of Exhaust section: Outer Duct, Inner cone, radial struts
Parts of Afterburner - Answer- Spray Bars, Flame Holder, Screech Liner, Variable
Exhaust Nozzle
Purpose of Afterburner Section - Answer- "Thrust Augmentation" is a method used to
increase the max thrust available from an engine by 50% or more.
Afterburner Ignition - Answer- Spark ignition (spark ignitor, most common)
Torch ignition (pilot light)
Hot Streak Ignition (ignited fuel streaks through turbine)
Spray Bars - Answer- introduce fuel to exhaust section to raise exiting gas temp, greatly
accelerating the gases rearward
Flame Holders - Answer- help in mixing fuel and air and stabilize flames in the duct
Screech Liner - Answer- Perforated sleeves installed in the duct to reduce pressure
fluctuations and vibrations by acting as a form of shock absorber.
, Variable-Exhaust Nozzle - Answer- "Turkey Feathers" is the iris arrangement of thin
metal plates to allow the nozzle to open during afterburner use and close for basic
subsonic operation. (prevents back pressure and engine stalls)
7 Parts of Reciprocating Engine - Answer- 4Cs, 2Ps, 2Vs
Crankcase
Cylinders
Connecting Rods
Crankshaft
Pistons
Plugs (spark)
Valves
Valve-operating mechanism
TSFC - Answer- Thrust Specific Fuel Consumption - Amount of fuel required to produce
one pound of thrust
Turbo Comparison Chart - Answer- Be able to draw it
Turbo Jet - Answer- Pros: Lightest Specific weight (weight per pound of thrust
produced), higher and faster than any other engine
Cons: Low propulsive efficiency at low forward speeds, relatively high TSFC at low alt
and low airspeeds, long takeoff roll required
Turbo Fan - Answer- Pros: Higher thrust at low airspeeds, lower TSFC, shorter takeoff
distance, noise reduction
Cons: Higher specific weight, larger frontal area, inefficient at higher altitudes
Turbo Prop - Answer- Pros: high thrust at low airspeeds; excellent take-off, slow speed,
and low altitude characteristics; superior for lifting heavy loads off short and medium
length runways
Cons: Heavier and more complicated, limited speeds
Turbo Shaft - Answer- Delivers power through a shaft to drive something other than a
propeller. By definition, it will ALWAYS HAVE A FREE/POWER TURBINE
Free Power Turbine - Answer- A turbine not linked to a compressor and devots all its
energy to spinning the shaft.
Propeller Assembly - Answer- pitch change/dome assembly
blade assembly
hub assembly
WITH COMPLETE SOLUTIONS
Compressor Stall Recovery - Answer- Reduce aircraft attitude: reduce inlet AOA
Slowly retard the PCL to just below stall threshold: allows engine to catch up with inlet
air
Engage bleed valves: increase airflow
Slowly advance PCL when engine indications return to normal
Creep - Answer- Abnormal elongation of turbine blades due to overheating over long
periods of time, can result in permanent deformation.
Fir Tree - Answer- How turbine blades are attached (not welded) to allow for repeated
heating and cooling throughout life of engine.
Purpose of Exhaust Section - Answer- To direct the flow of hot gases rearward, causing
a high exit velocity of the gases while preventing turbulence
Exhaust Nozzle Types - Answer- Convergent (subsonic)
Convergent-Divergent (super sonic)
Parts of Exhaust section: Outer Duct, Inner cone, radial struts
Parts of Afterburner - Answer- Spray Bars, Flame Holder, Screech Liner, Variable
Exhaust Nozzle
Purpose of Afterburner Section - Answer- "Thrust Augmentation" is a method used to
increase the max thrust available from an engine by 50% or more.
Afterburner Ignition - Answer- Spark ignition (spark ignitor, most common)
Torch ignition (pilot light)
Hot Streak Ignition (ignited fuel streaks through turbine)
Spray Bars - Answer- introduce fuel to exhaust section to raise exiting gas temp, greatly
accelerating the gases rearward
Flame Holders - Answer- help in mixing fuel and air and stabilize flames in the duct
Screech Liner - Answer- Perforated sleeves installed in the duct to reduce pressure
fluctuations and vibrations by acting as a form of shock absorber.
, Variable-Exhaust Nozzle - Answer- "Turkey Feathers" is the iris arrangement of thin
metal plates to allow the nozzle to open during afterburner use and close for basic
subsonic operation. (prevents back pressure and engine stalls)
7 Parts of Reciprocating Engine - Answer- 4Cs, 2Ps, 2Vs
Crankcase
Cylinders
Connecting Rods
Crankshaft
Pistons
Plugs (spark)
Valves
Valve-operating mechanism
TSFC - Answer- Thrust Specific Fuel Consumption - Amount of fuel required to produce
one pound of thrust
Turbo Comparison Chart - Answer- Be able to draw it
Turbo Jet - Answer- Pros: Lightest Specific weight (weight per pound of thrust
produced), higher and faster than any other engine
Cons: Low propulsive efficiency at low forward speeds, relatively high TSFC at low alt
and low airspeeds, long takeoff roll required
Turbo Fan - Answer- Pros: Higher thrust at low airspeeds, lower TSFC, shorter takeoff
distance, noise reduction
Cons: Higher specific weight, larger frontal area, inefficient at higher altitudes
Turbo Prop - Answer- Pros: high thrust at low airspeeds; excellent take-off, slow speed,
and low altitude characteristics; superior for lifting heavy loads off short and medium
length runways
Cons: Heavier and more complicated, limited speeds
Turbo Shaft - Answer- Delivers power through a shaft to drive something other than a
propeller. By definition, it will ALWAYS HAVE A FREE/POWER TURBINE
Free Power Turbine - Answer- A turbine not linked to a compressor and devots all its
energy to spinning the shaft.
Propeller Assembly - Answer- pitch change/dome assembly
blade assembly
hub assembly
