Part 66 Preparation

15.4 Compressors

The two main functional elements of centrifugal compressor are the ?
1. Rotor and stator
2. Impeller and diffuser
3. Compressor and turbine
The combination of the compressor stages and turbine stages on a common shaft is an engine referred to as ?
1. Manifold assy
2. Engine spool
3. Pulse jet
Compression ratio varies with …… ?
1. Rpm
2. Egt
3. Burner pressure
Compressors are designed to be most efficient in the ?
1. Lower rpm range of operation
2. Higher rpm range of operation
3. Higher temperature range
If a conversion from pressure to velocity is needed ……………………….. Which type of duct Is used ?
1. A convergent duct
2. A divergent duct is used
3. No ducting is required for this conversion
One of the following is not a centrifugal compressor advantage ?
1. Losses in turns between stages
2. High pressure rise per stage
3. Low weight
Stall or surge are accompanied by rapid changes in ……… ?
1. Rpm only
2. Egt only
3. Rpm, egt,epr
These can be balanced without disassembly of the engine ?
1. Hpc front blades
2. Fan blades
3. Turbine blades
The variable stator vanes or vsv are located………?
1. In front of rotor blades
2. Behind the rotor blades
3. Behind the diffuser section
The main difference between variable inlet guide vane (vigv) and a variable stator vane (vsv) is ?
1. Their position with regard to the rotor blades
2. The angle of air dilevery to compressor
3. Pressure rise per stage

15.3 Inlet

The airflow through the engine must always stay _________?
1. Above mach 1
2. Mach 1
3. Below mach 1
The airinlet duct is considered an ?
1. Airframe part
2. Engine part
3. Fuselage
The amount of change in duct area and the magnitude of the shock are varied ?automatically with ?
1. Airspeed of the aircraft
2. Ambient temperature
3. speed of compressor
Icing effects ice buildup increases ______ and reduces__________?
1. Lift, drag
2. Drag, lift
3. Drag, thrust
Inlet ducts are designed to function as ?
1. Convergent duct
2. Divergent duct
3. Diffusers
Which devices are used to straighten the air flow, then they also have antiicing air flowing through ?
1. Nozzel guid vanes
2. Outlet guid vanes
3. Inlet guid vanes
What happen fule with Increased aerodynamic drag due to ice formation ?
1. Decreases fuel consumption
2. Increases fuel consumption
3. Fuel consumption remains constant
What type of intake is one that decreases gradually in area and then increases ?
1. Convergent
2. Divergent
3. Convergent / divergent
A uniform and steady airflow is necessary to avoid ?
1. Compressor stall
2. Excessive temp in the turbine section
3. Both
Supersonic inlets are used to slow the incoming engine air to __________ before it enters the engine ?
1. More than mach 1
2. Less than mach 1
3. Mach 1

15.2 Engine Performance

Choked nozzle means the highest eﬃciency has been obtained in the engine for ?
1. Subsonic flight
2. Supersonic flight
3. Transonic flight
The bypass ratio of 4:1, indicates ?
1. 4 for core, 4 for bypass
2. 4 for core, 1 for bypass
3. 4 for bypass, 1 for core
One horse power is equal to ?
1. 375 meter/h
2. 375 mile/h
3. 375 km/h
The free turbine is located ________ of the engine turbine ?
1. Upstream
2. Downstream
3. In front
Gross thrust - ram drag = ?
1. Net thrust
2. Total drag
3. Induced drag
The basic parameter for describing the fuel economy of aircraft engines is usually ?
1. Thrust
2. Weight
3. Specific fuel consumption
The turbofan generates thrust by giving a relatively _____ acceleration to a large quantity of air ?
1. Greater
2. Slower
3. Faster
As the altitude increases the density _______ ?
1. Remains constant
2. Increases
3. Decreases
Humidity effects mostly the power of ------ ?
1. Jet engine
2. Reciprocating engine
3. Turbo fan engine
Thrust horse power = ?
1. Net thrust x aircraft velocity / 375
2. Net thrust - aircraft velocity
3. Net thrust - aircraft velocity / 375

15.4 Compressors