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Military

AL0993 Practice Exercise Answer Key & Review
Lesson 3: Systems and Accessories

True - False
  1.   The most common ignition system in Army gas turbine engines produces high tension voltage by conventional induction coils.

  False
  2.   Fuel is invariable conducted between the parts of the system through flexible lines.

  False
  3.   Oil is cooled in some gas turbine engines by transferring the heat in the oil to the fuel flowing to the fuel nozzles.

  True
  4.   Because the burning process is continuous in a gas turbine engine, the amount of cooling air is greater than the amount of combustion air.

  True
  5.   The pressurizing and drain dump valves may be used to prime the fuel control.

  True
  6.   The fuel pump may be built into the fuel control, or it may be a separate component.

  True

Cluster True - False
Each of the following groups of questions is related to the statement that precedes them.

FIRST GROUP
Gas turbine engines may have several fuel filters. Which of the following statements about them are True and which False?
  7.   Usually a filter includes a relief valve to open at a specified differential pressure.

  True
  8.   A filter made of stainless steel mesh cloth used to filter particles larger than 40 microns is called a cylindrical screen filter.

  True
  9.   Filters may be located in other places in the fuel system besides the main lines.

  True
10.   A paper cartridge filter removes particles larger than 100 microns.

  True
11.   A cylindrical screen filter is used where the fuel pressure is high.

  False
SECOND GROUP
The text tells you that ignition systems are of three general types. Which of these questions on them are True and which False?
12.   All gas turbine engines have two or more igniter plugs.

  False
13.   The high-energy capacitor type of ignition system actually produces a small amount of energy.

  True
14.   The annular-gap igniter plug electrode can operate at a cooler temperature than that of the constrained-gap plug.

  False
15.   In gas turbine engines, ignition takes place in microseconds.

  True
16.   Electrodes of gas turbine igniters and of conventional spark plugs can accommodate the same amount of energy.

  False
17.   Severely damaged ignition exciter units should be handled with forceps or gloves because they may be radioactive.

  True
THIRD GROUP
About lubrication systems for gas turbine engines, your text tells you that:
18.   Oil for gas turbine engines has a conventional petroleum base.

  False
19.   In most turbine engines, the oil is stored separately from the engine.

  True
20.   Pressure developed by a gear pump has no relation to engine rpm.

  False
21.   Oil drawn from the engine by scavenge pumps is discarded.

  False
22.   A gerotor pump has a tooth missing in its inner toothed element.

  True
23.   The oil tank is usually made of welded aluminum or steel.

  True
24.   The sole purpose of the lubrication system is to reduce friction.

  False
FOURTH GROUP
Which of the following six statements about the automatic and manual fuel control systems are True and which False?
25.   The amount of fuel needed to run the engine varies with inlet air temperature and pressure.

  True
26.   Automatic fuel control is provided by the speed governor.

  True
27.   The manual throttle control compensates for altitude and temperature.

  False
28.   Most fuel controls in use today are hydromechanical.

  True
29.   The speed governor is merely a spring attached to the manual metering valve.

  False
FIFTH GROUP
About the starting-fuel system, your text tells you that:
30.   All gas turbine engines have the same number of start-fuel nozzles.

  False
31.   The pilot turns on the start-fuel solenoid switch in the cockpit.

  True
32.   The start fuel flows directly from the external line to the fuel nozzles.

  False
33.   The nozzles spray atomized fuel in the combustion chamber during starting.

  True
34.   The start fuel system is shut off when the engine is running on the main fuel system.

  True
SIXTH GROUP
On the subject of fuel nozzles, your text says that:
35.   A simplex nozzle can provide as satisfactory a spray pattern as a duplex nozzle.

  False
36.   All gas turbine engines use fuel nozzles.

  False
37.   A duplex nozzle must have a fuel-flow divider.

  True
38.   A fuel-flow divider separates the fuel into low and high pressure supplies.

  True
39.   A spring-loaded valve is set to open at a specific fuel pressure; this is the fuel divider.

  True
SEVENTH GROUP
Your text discusses the hydromechanical type of fuel control. Evaluate the next five statements on the subject.
40.   Fuel flow has no relation to exhaust gas temperature.

  False
41.   Fuel control may be achieved by varying the orifice of the metering valve.

  True
42.   As the engine accelerates and airflow through the engine increases, fuel flow is decreased.

  False
43.   A fuel control with a longer acceleration time than would be used for a reciprocating engine must be used because engine compressors are subject to surges and stalls.

  True
44.   One of the factors that limits engine operation is temperature of the compressor inlet.

  True
Matching

In questions 45 through 50, match the statements in column I with the laws or principles of physics in column II by selecting the proper letter under each question. Each item in column II may be used once, more than once, or not at all.
45.   A generator supplies power to drive the synchronous motors in the indicator
  A.  Tachometer.
46.   Operates from an engine thermocouple harness.
  D.  Exhaust gas temperature indicator.
47.   Uses an electrical resistance thermobulb.
  C.  Engine oil temperature indicator.
48.   Transmitter connected by a hose to a pressure tap.
  B.  Engine oil pressure indicator.
49.   Is a sensitive millivoltmeter.
  D.  Exhaust gas temperature indicator.
50.   Registers engine and rotor rpm for rotary wing aircraft.
  A.  Tachometer.

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Lesson 4
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