#2 powerplant mocks

a

The stator vanes in an axial-flow compressor  
a. Convert velocity energy into pressure energy
b. Convert kinetic energy into potential energy
c. Convert pressure energy into velocity energy
d. Direct air into the first stage rotor vanes at the proper angle

b

Determine the jet thrust if the mass flow of the air is 50 lbs/second, as the inlet velocity is 734 ft/sec and the jet velocity is 1,300 feet/sec.
a. 788.8 lbs
b. 878.9 lbs
c. 978.7 lbs
d. 1,178.8 lbs

b

An ideal diesel engine has a compression ratio of 20 and uses air as the working fluid. The state of air at the beginning of the compression process is 95 kPa and 20 deg C. If the maximum temperature in the cycle is not to exceed 2200 K, determine the mean effective pressure.
a. 276 kPa
b. 456 kPa
c. 933 kPa
d 586 kPa

b

Cv is less than Cp.

a; It depends on the cycle
b. Always
c. Sometimes
d. Never

d

One cause of afterfiring in an aircraft engine is

a. Sticking intake valves
b. Poor ignition
c. Excessively lean mixture
d. Excessively rich mixture

d

With an increase in the rotational speed of a four-stroke engine the valve overlap

a. Increases
b. Increases up to the ground idle and thereafter decreases
c. Decreases
d. Remains Constant

c

Severe rubbing of turbine of turbine engine compressor blades will usually cause.

a. Bowing
b. Cracking
c. Galling
d. Distortion

b

Helium (R=0.4968 BTU/lbm-R) is compressed isothermally from 14.7 psia and 68 degree F, the compression ratio is 4. Calculate the work done by the gas in BTU/lbm.

a. -355
b. -364
c. -456
d. -576

b

To aid in identifying the different grades of aviation fuel, each fuel grade is color-coded with dye for easy visual identification. The color code for the 100 octane rating aviation gasoline is

a. Blue
b. Green
c. Red
d. Yellow

a

A large rocket engine delivers hydrogen at 1500 degree C and 3 MPa, k = 1.41, R = 4124 J/kg-K, to a nozzle which exits with gas pressure equal to the ambient pressure of 54 kPa. Assuming isentropic flow, if the rocket thrust is 2 MN, estimate the exit velocity.

a. 5890 m/s
b. 8950 m/s
c. 9580 m/s
d. 5980 m/s

a

If the value of n = 0 in the equation pv^n = C, then the process is called

a. Constant Pressure Process
b. Isothermal Process
c. Constant Volume Process
d. Adiabatic Process

a

Compute the indicated horsepower for a six-cylinder engine that has a bore of 5 in, a stroke of 5 in, and is turning at 2750 rpm with a measured IMEP of 125 lbs/sq.in per cylinder.

a. 255 hp
b. 315 hp
c. 550 hp
d. 415 hp

d

A method of comparing engine efficiencies is by comparing

a. Engine thrust rating
b. Fuel consumption
c. Thrust-to-weight ratio
d. Specific fuel consumption

d

The maximum thrust that a jet engine can develop will be
a. Take-off thrust
b.Go-around thrust
c. Max climb thrust
d. Max static thrust

a

With a governor-controlled propeller system, what happens to the propeller blade angle as the aircraft accelerates during the take-off?

a. Blade angle increases
b. Blade angle decreases
c. Blade angle does not change
d. Blade angle may increase or decrease depending on the particular system

b

What most likely to happen in an engine that start normal, EGT within limits but engine fails to accelerate in reach the idle rpm?

a. Hot start
b. Hung start
c. False start
d. Fail start

c

Calculate the indicated horsepower for a four-cylinder engine that has a bore of five inches and is turning at 2750 rpm with a measured IMEP of 500 psi for all cylinders. Assume square engine.

a. 175.11 hp
b. 180.12 hp
c. 170.13 hp
d. 169.14 hp

c

The highest pressure in a gas turbine is
a. At the nozzle exit
b. At the burner exit
c. Before the burner
d. Before the nozzle exit

c

The purpose of the crankcase breather is to

a. Maintain the pressure in the oil tank at atmospheric pressure
b. Ease the task of the oil scraper ring
c. Prevent pressure building up inside the crankcase
d. Prevent distortion of the crankcase

b

A single cylinder, four stroke cycle, 1800 rpm piston engine operates on a constant volume air cycle, compression ratio is 6 and the cylinder work input is 15.7 BTU/cycle. What is the thermal efficiency?

a. 0.41
b. 0.51
c. 0.23
d. 0.35

c

A weak fuel-to-air mixture along with normal airflow through a turbine engine may result in

a. A rich flameout
b. A high EGT
c. A lean die out
d. Detonation

c

Ram effect is
a. The increase of dynamic pressure at the face of the compressor
b. Conversion of static energy to kinetic energy at the face of the compressor
c. Conversion of kinetic energy to pressure energy at the face of the compressor
d. The increase of static energy at the face of the compressor

c

Consider as a system the gas contained in the cylinder which is fitted with a piston on which a number of small weights are placed. The initial pressure is 200 kPa and the initial volume of the gas is 0.04 cu.m. Let a Bunsen burner be placed under the cylinder and let the volume of the gas increase to 0.1 cu.m while pressure remains constant. Calculate the work done by the system during the process.

a. 5.31 kJ
b. 6.41 kJ
c. 7.33 kJ
d. 10.44 kJ

d

EPR is a
a. Ratio between ambient pressure and exhaust pressure
b. Ratio between ambient pressure and fan pressure
c. Ratio between intake pressure and compressor delivery pressure
d. Ratio between exhaust pressure and intake pressure

d

When is the fuel/air mixture ignited in a conventional reciprocating engine?
a. When the piston has reached top dead center of the intake stroke
b. Shortly after the piston reaches the top of the compression stroke
c. Right when the piston reaches the top dead center on the compression stroke
d. Shortly before the piston reaches the top of the compression stroke

a

A frictionless piston-cylinder device contains 10 lbm of steam at 60 psia and 320°F. Heat is now transferred to the steam until the temperature reaches 400°F. If the piston is not attached to a shaft and its mass is constant, determine the work done by the steam during this process.

a. 96.4 BTU
b. 92.6 BTU
c. 100.6 BTU
d. 94.6 BTU

c

Variable inlet guide vanes help to prevent

a. Loss compression
b. Ice build-up on the compressor blades
c. Compressor stalling
d. Foreign object on the compressor blades

b

Which of the following statement is wrong?
a. The closed cycle gas turbine plants are external combustion plants.
b. In the closed cycle gas turbine, the pressure range depends upon the atmospheric pressure
c. The advantage of efficient internal combustion is eliminated as the closed cycle has an external surface
d. In open cycle gas turbine, atmosphere acts as a sink and coolant are required.

b

A system suffers an increase in internal energy of 80 J and at the same time has 50 J of work done on it. What is the heat change of the system?

a. +130 J
b. +30 J
c. 130 J
d. -30 J

a

Excessive cylinder head temperatures are caused by
a. The prolonged use of weak mixtures.
b. The ignition timing being too far advanced.
c. The prolonged use of rich mixtures.
d. The ignition being too far retarded.

c

An ideal air-standard Diesel cycle engine has a compression ratio of 18 and a cutoff ratio of 2. At the beginning of the compression process, the working fluid is at 100 kPa, 27 deg C (300 K). Determine the net-work output per cycle in [kJ/kg], and the thermal efficiency.
a. 0.56
v. 0.57
c. 0.58
d. 0.59

b

A rich mixture is supplied to the cylinders at take-off and climb.
a. To give greater thermal efficiency.
b. To cool the charge temperature and prevent detonation.
c. To increase the volumetric efficiency.
d. To give excess power.

b

Find the T3 of an otto engine that has a compression ratio of 7. The engine operates on 0.5 lb/s of air from 13 psia and 80 deg F at the beginning of compression. The engine has a clearance of 10% and 200 BTU of heat are added per cycle.
a. 957
b. 1176
c. 1759
d. 2057

d

An aircraft uses clamshell doors for thrust reversal to
a. Direct the gas flow rearwards.
b. Block the flow of exhaust gas.
c. Absorb any change in thrust.
d. Change the direction of the exhaust gas.

c

With an increase in the rotational speed of a four-stroke engine, the valve overlap
a. Increases
b. Decreases
c. Remains constant
d. Increases up to ground idle and thereafter decreases

b

In a convergent duct
a. The pressure and velocity increase, the temperature decreases.
b. The pressure and temperature decrease, the velocity increases.
c. The temperature and velocity increase, the pressure decreases.
d. The pressure and velocity remain constant, the temperature decreases.

c

The device utilized to measure temperature on a piston engine is
a. Thermometer
b. Barometer
c. Thermocouple
d. Thermostat

a

The purpose of an ignition switch is
a. To control the primary circuit of the magneto
b. To prevent condensation
c. To connect the secondary coil to the distributor
d. To connect the battery to the magneto

b

The correct working cycle of a four-stroke engine is
a. Exhaust, Power, Induction, Compression
b. Compression, Power, Exhaust, Induction
c. Induction, Power, Compression, Exhaust
d. Power, Exhaust, Compression, Induction

d

For a turbo jet with flight velocity of 310 kilometers per hour and exhaust gas jet velocity of 690 kilometers per hour at atmospheric pressure, What is the propulsive efficiency with the fuel considered negligible?

a. 0.45
b. 0.53
c. 0.69
d. 0.62

b

The temperature of the gases within the cylinder of a four-stroke engine during the power stroke will
a. Be constant
b. Decrease
c. Increase
d. Follow Charles's Law

b

For a rocket engine to develop a thrust of 10,000 newtons, the 19.2 lb propellant consumed by the rocket per second must generate an exhaust gas jet velocity at atmospheric of what?

a. 1146.25 mps
b. 1148.25 mps
c. 1149.25 mps
d. 1147.25 mps

a

During an ideal Brayton cycle in jet engine, the process is isentropic in
a. process 1-2; process 3-4
b. process 3-4; process 4-1
c. process 2-3; process 1-4
d. process 1-2; process 2-3

d

In a gas turbine engine
a. Ram pressure is maximum at the start of the take-off run.
b. Ram pressure is unaffected by airspeed.
c. Thrust is unaffected by the aircraft's forward speed.
d. Thrust is maximum and ram pressure at minimum at the start of the take-off run.

b

The term Indicated Mean Effective Pressure refers to
a. The maximum working pressure in the engine cylinder.
b. The effective working pressure in the cylinder during the power stroke.
c. The pressure achieved during compression.
d. The minimum working pressure applied to the piston during the cycle.

c

Which of the following statement is incorrect?
a. The liquid fuels consist of hydrocarbons
b. The liquid fuels have higher calorific value than solid fuels
c. The solid fuels have higher calorific value than liquid fuels
d. A good fuel should have low ignition point

a

What publication is used for guidance to determine whether a powerplant repair is major or minor?
a. FAR Part 43
b. Maintenance Manual
c. Far Part 91
d. 14 CFR 25

a

In the relationship between manifold pressure, rpm, collective, and throttle, if the manifold pressure is LOW and the rpm is HIGH the solution will be
a. Lower the collective pitch
b. Decrease manifold pressure
c. Increase the throttle
d. Increase manifold pressure and rpm

c

The length of the stroke is
a. Equal to the length of the cylinder
b. Determined by the size of the piston
c. Equivalent to twice the crank throw
d. Inversely proportional to the engine power output

a

Shrouding of stator blade tips is designed to
a. Minimize vibration
b. Prevent tip turbulence
c. Prevent tip losses
d. Ensure adequate cooling