# 2a762 Volume 1 Ure Part 2

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Unit Review Questions from CDC 2A672 Volume 1

• 1.

### Refer to foldout 1.  During operation of the -86D, you get no response when you place S13 in the GENERATE position.  A check of voltage at J8, terminal N, shows 12 volts direct current (VDC).  What is the probable cause of this trouble?

• A.

M4 is open

• B.

S53 is open

• C.

K23 is open

• D.

K16 is open

B. S53 is open
Explanation
The probable cause of the trouble is that S53 is open. This means that the switch S53, which is responsible for generating a response when placed in the GENERATE position, is not functioning properly. This can be deduced from the fact that there is a 12-volt direct current (VDC) at J8, terminal N, indicating that the power supply is working fine. Therefore, the issue lies with the open switch S53, which is preventing the desired response from occurring.

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• 2.

### Refer to foldout 1.  You are operating -86D at governed speed, but voltage doesn't build up.  What is the probable cause of this trouble?

• A.

S1 is in the automatic position

• B.

R61 is turned fully clockwise

• C.

K16 contacts are closing

• D.

K23 contacts are open

D. K23 contacts are open
Explanation
The probable cause of the voltage not building up when operating -86D at governed speed is that the K23 contacts are open.

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• 3.

### Refer to foldout 1.  During an ops check of the -86D, the shutdown solenoid energizes immediately after the engine run indicator illluminates.  What is a probable cause of this trouble?

• A.

S48 open

• B.

S46 open

• C.

S49 shorted

• D.

S22 stuck open

C. S49 shorted
Explanation
The shutdown solenoid energizing immediately after the engine run indicator illuminates could be caused by S49 being shorted. This means that there is a direct connection between the two components, causing the solenoid to activate as soon as the engine run indicator turns on.

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• 4.

### Refer to foldout 1.  During operation of the -86D, the low coolant light (DS50) illuminates, but the unit does not shut down.  What is a probable cause of this trouble?

• A.

A2

• B.

DS50

• C.

S55 is closed

• D.

S48 is closed

A. A2
Explanation
The low coolant light (DS50) illuminates but the unit does not shut down because S55 is closed and S48 is closed.

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• 5.

### Refer to foldout 1.  Which statement best reflects what happens if S46 shorts during operation of a -86D generator?

• A.

12 VDC would be present at terminal A of S55

• B.

There would be no change to unit operation

• C.

M5 would go into an overspeed condition

• D.

S55 would ause L6 to de-energize

A. 12 VDC would be present at terminal A of S55
Explanation
If S46 shorts during operation of a -86D generator, 12 VDC would be present at terminal A of S55.

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• 6.

### What component controls the strength of the -86D exciter field L2?

• A.

Excitation relay K16

• B.

Time delay relay K14

• C.

Voltage regulator VR1

• D.

Automatic manual switch S1

C. Voltage regulator VR1
Explanation
The voltage regulator VR1 controls the strength of the -86D exciter field L2. This means that VR1 is responsible for regulating the voltage supplied to the exciter field, which in turn determines the strength of the field. By adjusting the voltage, VR1 can control the level of excitation in the field, allowing for precise control over the generator's output.

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• 7.

### Refer to foldout 1.  Where is the best point to check voltage to the -86D exciter field?

• A.

J8, terminal D-F

• B.

J8, terminal V-X

• C.

VR1. terminal C-R

• D.

Automatic-manual switch S1

A. J8, terminal D-F
Explanation
The best point to check voltage to the -86D exciter field is at J8, terminal D-F. This is because J8 is the designated terminal for checking voltage in this circuit, and the D-F terminals specifically correspond to the exciter field. Therefore, checking voltage at J8, terminal D-F would give the most accurate and relevant measurement for the exciter field.

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• 8.

### A -86D is operating and the alternating current (AC) voltmeter is reading 200 volts alternating current (VAC) on all three phases.  What do you do?

• A.

• B.

• C.

• D.

Switch S15 to the L-N position

D. Switch S15 to the L-N position
Explanation
Switch S15 to the L-N position. This is the correct answer because when an AC voltmeter is reading 200 VAC on all three phases, it indicates that the voltmeter is connected in a delta configuration. Switching S15 to the L-N position will change the configuration to a wye configuration, which is the correct configuration for measuring voltage in this scenario. Adjusting VR1 or R61 would not address the issue of incorrect configuration.

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• 9.

### Refer to foldout 1.  A -86D is sent to the the shop on a Red X for "will not apply power to the aircraft."  During the ops check, you place S5 in the closed position and the contactor light illuminates.  When you release the switch, the contactor opens.  What is the probable cause of this trouble?

• A.

S2 is open

• B.

R46 is open

• C.

K2 is closed

• D.

K17 is closed

B. R46 is open
Explanation
The probable cause of the trouble is that R46 is open. This can be inferred from the given information that when S5 is placed in the closed position, the contactor light illuminates, but when the switch is released, the contactor opens. This behavior indicates that there is an issue with the circuit, and the most likely cause is that R46, which is responsible for maintaining the closed circuit, is open.

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• 10.

### While operating a -86D at governed speed, you place S13 in the build up position and the undervoltage light comes on.  What is the probable cause of this trouble?

• A.

Voltage regulator

• B.

Plug interlock relay

• C.

Memory time delay relay

• D.

Overvoltage/undervoltage relay

C. Memory time delay relay
Explanation
The probable cause of the undervoltage light coming on when placing S13 in the build-up position while operating a -86D at governed speed is the memory time delay relay. The memory time delay relay is responsible for delaying the response of the undervoltage relay to prevent false alarms during momentary voltage fluctuations. In this case, it seems that the memory time delay relay is not functioning properly, causing the undervoltage light to come on when it shouldn't.

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• 11.

### The -86D is applying 115 VAC to the aircraft and all of a sudden the AC contactor opens and there is no voltage indication on M2.  What is the probable cause of this trouble?

• A.

• B.

CR 17 forward biased

• C.

Overvoltage/undervoltage relay

• D.

Memory time-delay relay energized

D. Memory time-delay relay energized
Explanation
The probable cause of the trouble is that the memory time-delay relay is energized. This relay is designed to introduce a delay in restoring power after a power interruption or fault. In this case, the relay has been activated, causing a delay in the restoration of voltage to M2. This could be due to a malfunction or a deliberate activation of the relay.

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• 12.

### You are driving on the flight line and notice a -86D power unit with all the fault lights on.  You try to reset S23, but the lights stay on.  What is a probable cause of this trouble?

• A.

S30 is shorted

• B.

S23 is stuck open

• C.

K17 contacts are closed

• D.

K23 contacts are open

A. S30 is shorted
Explanation
A probable cause of the trouble is that S30 is shorted. This means that there is a direct connection between the terminals of S30, causing a short circuit. As a result, the fault lights on the -86D power unit remain on even after attempting to reset S23. This suggests that the issue lies with S30 rather than S23 or any other component mentioned in the options.

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• 13.

### What component on the B809A generator set fuel system distributes and delivers an accurate amount of fuel to the engine cylinders?

• A.

Injector pump

• B.

Transfer pump

• C.

Injector nozzles

• D.

Throttle actuator

A. Injector pump
Explanation
The injector pump is the component on the B809A generator set fuel system that distributes and delivers an accurate amount of fuel to the engine cylinders. It is responsible for pressurizing the fuel and delivering it to the injectors, which then atomize the fuel and inject it into the engine cylinders for combustion. The injector pump plays a crucial role in ensuring the proper fuel-air mixture for efficient engine operation.

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• 14.

### What contacts on the annunciator card of the B809A generator set control the alternating current (AC) power input to the voltage regulator?

• A.

Engine fault

• B.

Regulator fault

• C.

Generator fault

• D.

Contactor fault

C. Generator fault
Explanation
The contacts on the annunciator card of the B809A generator set that control the AC power input to the voltage regulator are the generator fault contacts. These contacts are responsible for detecting any faults or issues with the generator, which in turn affects the power input to the voltage regulator. If there is a fault with the generator, it can disrupt the AC power input to the voltage regulator and potentially cause issues with the overall functioning of the generator set.

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• 15.

### What signal powers the regulator card output pulse sent to the exciter field of the B809A generator?

• A.

28.5 volts direct current (VDC)

• B.

110 VDC

• C.

115 volts alternating current (VAC)

• D.

200 VAC

B. 110 VDC
Explanation
The regulator card output pulse sent to the exciter field of the B809A generator is powered by 110 VDC.

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• 16.

### What B809A generator set engine safety circuit incorporates a seven-second time delay before activation?

• A.

Low fuel fault

• B.

Overspeed fault

• C.

Low lube pressure

• D.

Coolant temperature

C. Low lube pressure
Explanation
The correct answer is low lube pressure. The low lube pressure safety circuit in the B809A generator set engine incorporates a seven-second time delay before activation. This delay allows the engine to reach a safe operating temperature before shutting down due to low lubrication pressure. This feature helps prevent unnecessary engine damage and ensures the longevity of the generator set.

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• 17.

### What action occurs when the B809A generator set AC card senses an AC supply fault?

• A.

Only generator output stops

• B.

Only the AC contactor opens

• C.

AC supply warning light illuminates

• D.

AC contactor opens and generator output stops

D. AC contactor opens and generator output stops
Explanation
When the B809A generator set AC card senses an AC supply fault, the AC contactor opens and the generator output stops. This means that the AC contactor, which is responsible for connecting and disconnecting the generator set to the AC supply, opens to disconnect the generator from the faulty AC supply. As a result, the generator output also stops because it is no longer connected to the AC supply. This action helps to prevent any further damage or issues that may arise from the faulty AC supply.

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• 18.

### What condition is sensed by the DC card on the B809A generator set?

• A.

Overtemperature

• B.

Under frequency

• C.

Overfrequency

• D.

Low fuel

A. Overtemperature
Explanation
The DC card on the B809A generator set senses the condition of overtemperature. This means that the card is designed to detect and monitor the temperature of the generator set, and if it exceeds a certain threshold, it will trigger an alarm or shutdown to prevent any potential damage or malfunction caused by overheating.

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• 19.

### Refer to foldout 2.  While operating a B809A generator, what switch is closed to provide potential to the exciter field?

• A.

S1, master switch

• B.

S5, run/idle toggle switch

• C.

S3, interlock toggle switch

• D.

PB2, output control pushbutton switch

B. S5, run/idle toggle switch
Explanation
The correct answer is S5, run/idle toggle switch. When operating a B809A generator, closing the run/idle toggle switch will provide potential to the exciter field. This switch controls the generator's operation by toggling between the run and idle modes. By closing this switch, the exciter field is energized and allows the generator to produce power.

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• 20.

### What gas turbine engine component is specifically designed to break if the engine locks up?

• A.

Second stage impeller

• B.

First stage diffuser

• C.

Compressor shaft

• D.

Torsion shaft

D. Torsion shaft
Explanation
The torsion shaft is specifically designed to break if the engine locks up. This component is responsible for transmitting torque from the engine to the compressor and fan blades. If the engine locks up, it can cause a sudden increase in torque, which can lead to catastrophic failure of the engine. By designing the torsion shaft to break, it acts as a safety mechanism, preventing further damage to the engine and reducing the risk of a complete engine failure.

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• 21.

### During the operation of a -60A, you notice the exhaust gas temperature is excessively high.  What is the probable cause of this trouble?

• A.

Air oil seals

• B.

Fuel atomizer

• C.

Torus assembly

• D.

Pneumatic thermostat

D. Pneumatic thermostat
Explanation
The probable cause of the excessively high exhaust gas temperature in a -60A could be a malfunctioning pneumatic thermostat. The pneumatic thermostat is responsible for regulating the temperature of the engine by controlling the flow of air or fuel. If it is not functioning properly, it may result in an imbalance in the fuel-air mixture, leading to higher exhaust gas temperature.

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• 22.

### In the lubrication system of the -60A gas turbine engine, how does the oil pressure relief valve control the output of the main oil pump?

• A.

Through the filter bypass valve

• B.

Through the oil pressure sequencing switch

• C.

It bypasses excess oil back to the oil filter inlet

• D.

It bypasses excess oil back to the main pump inlet

D. It bypasses excess oil back to the main pump inlet
Explanation
The oil pressure relief valve controls the output of the main oil pump by bypassing excess oil back to the main pump inlet. This means that if the oil pressure exceeds a certain limit, the relief valve opens and allows the excess oil to flow back into the pump inlet, preventing any damage or malfunction due to excessive pressure. By diverting the excess oil, the relief valve helps to regulate and maintain a consistent oil pressure within the lubrication system of the gas turbine engine.

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• 23.

### What component of the -60A lubrication system on a gas turbine engine draws excess oil from the gear case?

• A.

Oil cooler

• B.

Main oil pump

• C.

Scavenge pump

• D.

Oil jet assembly

C. Scavenge pump
Explanation
The scavenge pump is responsible for drawing excess oil from the gear case in the -60A lubrication system on a gas turbine engine. This pump is designed to remove any oil that is not being used for lubrication and return it to the oil tank for recirculation. By doing so, the scavenge pump helps to maintain the proper oil level and prevent any potential damage or malfunction caused by an excess of oil in the gear case.

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• 24.

### Refer to foldout 5.  You're out on the flight line checking the fuel levels on power units and, as you pull up to a -60A, you notice a puddle of liquid.  As you investigate further, you see that fuel is coming out of the main tank fuel cap.  What is the probable cause of this trouble?

• A.

S20A failed to close

• B.

S20B failed to close

• C.

S18 failed to close

• D.

S9 failed to close

B. S20B failed to close
Explanation
The probable cause of the fuel coming out of the main tank fuel cap is that S20B failed to close.

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• 25.

### While performing an ops check of the -60A, you notice the unit is only operating at 97 percent.  What is the probable cause of this trouble?

• A.

110 percent centrifugal switch

• B.

Fuel pump and control unit

• C.

Acceleration limiter valve

• D.

Governor trim control

D. Governor trim control
Explanation
The probable cause of the trouble is the governor trim control. The governor trim control is responsible for adjusting the speed of the engine to maintain a constant RPM. If the unit is only operating at 97 percent, it suggests that the governor trim control is not functioning properly and is not able to maintain the desired speed.

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• 26.

### The rate adjustment screw in the -60A is used to adjust the rate at which chamber

• A.

4 depressurizes

• B.

3 depressurizes

• C.

2 depressurizes

• D.

1 depressurizes

A. 4 depressurizes
Explanation
The rate adjustment screw in the -60A is used to adjust the rate at which chamber 4 depressurizes.

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• 27.

### Refer to foldout 5.  During operation of the -60A, the engine rotates, but there is no combustion.  What is the probable cause of this trouble?

• A.

K8

• B.

L9

• C.

S13

• D.

S11

D. S11
Explanation
The probable cause of the engine rotating but no combustion during operation of the -60A is issue with the ignition system.

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• 28.

### Refer to foldout 5.  A -60A comes into the shop on a Red X for "unit won't start".  You do a quick check of the unit, and find the panel lights, boost pump, and ready to load press-to-test light are working.  What is the probable cause of this trouble?

• A.

S18 is closed

• B.

S8 is stuck closed

• C.

K4 is de-energized

• D.

S10 is in the OFF position

A. S18 is closed
Explanation
The probable cause of the trouble is that S18 is closed. This means that the switch S18, which is responsible for starting the unit, is in the closed position. This would prevent the unit from starting as it should be in the open position for the unit to start.

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• 29.

### Refer to foldout 5.  While operating a -60A, you reset the AC contactor switch, but the voltage did not build up.  What should have happened within the K11 relay?

• A.

K11A de-energized, opening N and P contacts

• B.

K11B energized, closing N and P contacts

• C.

K11B energized, opening N and P contacts

• D.

K11A energized, closing N and P contacts

B. K11B energized, closing N and P contacts
Explanation
When operating a -60A, resetting the AC contactor switch should have caused the K11B relay to energize, closing the N and P contacts. This means that the correct answer is K11B energized, closing N and P contacts.

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• 30.

### Refer to foldout 5.  During operation of the -60A, you close S3, but the AC contactor light does not come on.  What is the probable cause of this trouble?

• A.

CB1 opened

• B.

K11B energized

• C.

K11A de-energized

• D.

K11 contacts C and D opened

D. K11 contacts C and D opened
Explanation
The probable cause of the trouble is that the contacts C and D of K11 have opened. This means that there is a break in the circuit, preventing the flow of electricity to the AC contactor light. As a result, even though S3 is closed, the light does not come on.

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• 31.

### Refer to foldout 5.  The DC voltmeter on a -60A fails to indicate during operation.  What is the probable cause of this trouble?

• A.

K6 is defective

• B.

TR1 is defective

• C.

• D.

S4 is in the OFF position

B. TR1 is defective
Explanation
The probable cause of the DC voltmeter on a -60A failing to indicate during operation is that TR1 is defective.

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• 32.

### Refer to foldout 5.  Your -60A has been on a Red X twice for "dead batteries".  What is the probable cause of this trouble?

• A.

28 VDC at TR1

• B.

K16 contacts stuck closed

• C.

D1 allowing voltage to R6

• D.

D1 open

D. D1 open
Explanation
The probable cause of the trouble is that D1 is open. This means that the diode D1 is not allowing voltage to reach R6, which could be causing the dead batteries.

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• 33.

### Refer to foldout 5.  You place the start switch S7 on a -60A to the ON position to start the turbine engine.  The engine starts, but shuts down immediately after you release the switch.  What is the probable cause of this trouble?

• A.

95 percent centrifugal switch

• B.

Turbine control relay K18

• C.

Oil pressure switch S11

• D.

Start switch S7

B. Turbine control relay K18
Explanation
The probable cause of the trouble is the turbine control relay K18. When the start switch S7 is released, the turbine engine shuts down immediately. This suggests that the turbine control relay K18 is not functioning properly and is not able to maintain the power to the engine after the start switch is released.

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• 34.

### Apparent power is measured in

• A.

Kilovolts (KV)

• B.

Kilowatts (KW)

• C.

Kilo-volt-amperes (KVA)

• D.

Kilo-watt-amperes (KWA)

C. Kilo-volt-amperes (KVA)
Explanation
Apparent power is a measure of the total power in an electrical circuit, taking into account both the real power (in kilowatts) and the reactive power (in kilovolt-amperes). It is denoted as kilo-volt-amperes (KVA). This measurement is important in determining the overall power capacity and efficiency of electrical systems, as it considers the effects of both active and reactive components of power. Kilovolts (KV) and kilowatts (KW) are not accurate measurements for apparent power as they do not account for the reactive power component. Kilo-watt-amperes (KWA) is not a standard unit of measurement for apparent power.

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• 35.

### Use the power factor meter on a -8 load bank

• A.

• B.

When measuring true power

• C.

When measuring apparent power

• D.

During performing resistive and reactive load tests simultaneously

D. During performing resistive and reactive load tests simultaneously
Explanation
The power factor meter is used during performing resistive and reactive load tests simultaneously. This is because resistive load tests only measure true power, while reactive load tests measure both true power and apparent power. The power factor meter is necessary in this scenario to accurately measure the power factor, which is the ratio of true power to apparent power. By using the power factor meter, it is possible to determine the efficiency and effectiveness of the load bank in handling both resistive and reactive loads simultaneously.

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• 36.

### Refer to foldout 6.  The AC cable is plugged into the -8 load bank input panel and both blower motors are turning, but nothing happens when you turn the shock load switches on.  What is the probable cause of this trouble?

• A.

K110 is energized

• B.

K2 is de-energized

• C.

CB1 is malfunctioning

• D.

CR1 is malfunctioning

D. CR1 is malfunctioning
Explanation
The probable cause of this trouble is that CR1 is malfunctioning. CR1 refers to a component or relay that is responsible for controlling the shock load switches. If CR1 is malfunctioning, it means that it is not functioning properly and is unable to activate the shock load switches, resulting in nothing happening when they are turned on.

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• 37.

### Refer to foldout 6.  After you connect a -60A to the -8 load bank, you notice one of the blower motors isn't working on the load bank.  What is the probable cause of this trouble?

• A.

CR1

• B.

CR2

• C.

S66 and S67

• D.

K3 energized

B. CR2
Explanation
The probable cause of the blower motor not working on the load bank after connecting a -60A to the -8 load bank is CR2.

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• 38.

• A.

CB1

• B.

CR1

• C.

S56

• D.

S1

C. S56
• 39.

### Refer to foldouts 6 and 7.  If CB2 opens on the -8 load bank, what effect does it have on load bank operation?

• A.

AC load selecton switches (S15 through S20) won't work

• B.

AC load selection switches (S15 through S20) work

• C.

AC load selection switches (S9 through S14) work

• D.

Blower motor B2 won't work

A. AC load selecton switches (S15 through S20) won't work
Explanation
If CB2 opens on the -8 load bank, it will cause the AC load selection switches (S15 through S20) to not work.

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• 40.

### What is the operating voltage of the blower motor and control relays on a -8 load bank?

• A.

12 VDC

• B.

28 VDC

• C.

120 VAC

• D.

208 VAC

B. 28 VDC
Explanation
The operating voltage of the blower motor and control relays on a -8 load bank is 28 VDC.

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• 41.

### Refer to foldout 6.  You are testing a DC generator and notice the panel lights and blower motor (B2) on the -8 load bank are not working.  Where should you start troubleshooting?

• A.

K1

• B.

K2

• C.

CR2

• D.

PT2

B. K2
Explanation
You should start troubleshooting at K2.

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• 42.

### Refer to foldout 6.  On a -8 load bank, CR2 supplies 28 VDC to operate the panel lights, the wind switch assembly, and the

• A.

AC voltmeter

• B.

Transformer PT3

• C.

Blower motor B1

• D.

Blower motor B2

D. Blower motor B2
Explanation
CR2 supplies 28 VDC to operate the panel lights, wind switch assembly, and AC voltmeter. The blower motor B2 is also supplied by CR2. Therefore, the correct answer is blower motor B2.

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• 43.

### Refer to foldout 7.  What component supplies 28 VDC to the variable load selector switches on a -8 load bank?

• A.

CB1

• B.

CB2

• C.

PT1

• D.

PT2

B. CB2
Explanation
CB2 supplies 28 VDC to the variable load selector switches on a -8 load bank.

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• Current Version
• Jul 17, 2024
Quiz Edited by
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• Jan 08, 2012
Quiz Created by
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