Fill in the blanks
1. shorter
2. same
3. sum
4. length, area
5. sum
6. resistance
7. the same
8. motor
True or False
1. true
2. false
3. false
4. false
5. false
Knowledge Application
1. The current increases.
2. Series, parallel and series-parallel.
3. 12
4. Between 1.275 and 1.300.
5. Between 70 degrees and 90 degrees Fahrenheit.
6. A hydrometer.
7. Paint it with an asphaltic (tar base) paint or with polyurethane enamel.
8. A solution of bicarbonate of soda and water.
Multiple Choices
1. b
The total resistance of this circuit is 2 ohms. The total current flowing in this circuit is 6 amps.
2. c
3. b
The resistance of a conductor varies directly as its length, inversely as its cross-sectional area, and directly with the resistivity of its material.
Either decreasing the length or increasing the crosssectional area of a conductor will cause its resistance to decrease.
4. b
The permeability of a material is a measure of the ease with which lines of magnetic force can pass through it. Iron has the highest permeability of all the metals listed in this question.
5. a
6. a
In a parallel circuit each resistor forms a path for the current to follow and the total resistance is always smaller than that of the smallest resistor.
7. c
The voltage drop across a circuit is determined by two things: the resistance of the circuit and the amount of current flowing through it (the amperage).
In this question, the resistance of the circuit is fixed; therefore, the voltage drop is determined by the amperage in the circuit.
8. b
A thermal switch is another name for a built-in thermal circuit breaker. This is a circuit protection device that opens the circuit when the windings of the motor get too hot.
If the motor overheats for any reason, the thermal switch will open the power circuit to the motor and allow the motor to cool.
9. a
With the landing gear retracted, the red indicator light will not come on if there is an open in wire No. 19.
Wire No. 19 supplies power from the bus to the red indicator light, through the up-limit switch and through wire No. 8.
Wire No. 7 supplies power to the red indicator light for the press-to-test circuit.
Wire No. 17 supplies power to the green indicator light for its press-to-test circuit.
10. a
Wire No. 7 supplies power to both the red and green indicator lights from the 5-amp circuit breaker.
When either of the press-to-test lamps is pushed, the circuit is completed to ground, allowing the lamp to light up as long as it remains pressed.
Press-to-test lamps are used to allow the pilot to ascertain that the bulb in the lamp is good.
11. b
The green light will not come on when the landing gear is down if there is an open in wire No. 6. (Note: The switches in Figure are shown in the position for the gear down and the airplane on the ground.)
Wire No. 7 supplies power to both the red and green indicator lights from the 5-amp circuit breaker for the push-to-test circuit.
Wire No. 17 supplies power to the green indicator light for its push-to-test circuit.
12. c
Relay PCO provides 24-volt DC power from the bus through a 5-amp circuit breaker to the Fuel Pressure Crossfeed Valve Open caution warning light in the cockpit.
If relay PCO fails to operate, contacts 13 will not complete the circuit and the light will not illuminate, but the rest of the system will operate normally.
13. b
The fuel-selector switch must be in the Crossfeed (X-Feed) position for the relay TCO to close contacts 14.
When the tank selector is put in the X-Feed position, contacts 17 of relay FCF close, and current flows from the 24-volt DC bus, through a five-amp circuit breaker, into the “open” coils of the fuel tank X-Feed valve motor.
When the motor opens this valve, contacts 19 close and current flows to relay TCO closing contacts 14.
14. a
When the fuel selector switch is in the right-hand tank position and power is supplied from the bus, three relays (RTS, PCO, and TCC) will actuate.
Current flowing through the fuel-selector switch energizes the coil for relay RTS. This closes contacts 8 and opens contacts 7.
Current from the bus flows through closed contacts 5 of relay LTS, through contacts 8 of relay RTS that has just closed, and through the “open” winding of the fuel pressure X-Feed valve motor.
As soon as this motor fully opens the valve, contacts 12 close and energize relay PCO to close contacts 13 in the circuit for the Fuel Pressure Crossfeed Valve Open light.
Current flows from the bus through the right-hand five-amp circuit breaker and through the normally closed contacts 18 of the FCF relay, through contacts 20 in the Fuel Tank X-Feed Valve to the coil of relay TCC which opens its contacts 16.
15. a
As soon as electrical power is supplied to the 24-volt bus, two relays, PCC and TCC, are energized.
Current flows from the bus through the left-hand, five-amp circuit breaker and through contacts 5, 7, and 9 of the relays controlled by the fuel selector switch. It flows from contacts 9, through contacts 11 in the Fuel Pressure X-Feed valve, to the coil of relay PCC.
At the same time, current flows through the right-hand five-amp circuit breaker, through contacts 18 and then through contacts 20 in the Fuel Tank X-Feed valve to the coil of relay TCC.
OTHER QUESTIONS
1. shorter
2. same
3. sum
4. length, area
5. sum
6. resistance
7. the same
8. motor
True or False
1. true
2. false
3. false
4. false
5. false
Knowledge Application
1. The current increases.
2. Series, parallel and series-parallel.
3. 12
4. Between 1.275 and 1.300.
5. Between 70 degrees and 90 degrees Fahrenheit.
6. A hydrometer.
7. Paint it with an asphaltic (tar base) paint or with polyurethane enamel.
8. A solution of bicarbonate of soda and water.
Multiple Choices
1. b
The total resistance of this circuit is 2 ohms. The total current flowing in this circuit is 6 amps.
2. c
3. b
The resistance of a conductor varies directly as its length, inversely as its cross-sectional area, and directly with the resistivity of its material.
Either decreasing the length or increasing the crosssectional area of a conductor will cause its resistance to decrease.
4. b
The permeability of a material is a measure of the ease with which lines of magnetic force can pass through it. Iron has the highest permeability of all the metals listed in this question.
5. a
6. a
In a parallel circuit each resistor forms a path for the current to follow and the total resistance is always smaller than that of the smallest resistor.
7. c
The voltage drop across a circuit is determined by two things: the resistance of the circuit and the amount of current flowing through it (the amperage).
In this question, the resistance of the circuit is fixed; therefore, the voltage drop is determined by the amperage in the circuit.
8. b
A thermal switch is another name for a built-in thermal circuit breaker. This is a circuit protection device that opens the circuit when the windings of the motor get too hot.
If the motor overheats for any reason, the thermal switch will open the power circuit to the motor and allow the motor to cool.
9. a
With the landing gear retracted, the red indicator light will not come on if there is an open in wire No. 19.
Wire No. 19 supplies power from the bus to the red indicator light, through the up-limit switch and through wire No. 8.
Wire No. 7 supplies power to the red indicator light for the press-to-test circuit.
Wire No. 17 supplies power to the green indicator light for its press-to-test circuit.
10. a
Wire No. 7 supplies power to both the red and green indicator lights from the 5-amp circuit breaker.
When either of the press-to-test lamps is pushed, the circuit is completed to ground, allowing the lamp to light up as long as it remains pressed.
Press-to-test lamps are used to allow the pilot to ascertain that the bulb in the lamp is good.
11. b
The green light will not come on when the landing gear is down if there is an open in wire No. 6. (Note: The switches in Figure are shown in the position for the gear down and the airplane on the ground.)
Wire No. 7 supplies power to both the red and green indicator lights from the 5-amp circuit breaker for the push-to-test circuit.
Wire No. 17 supplies power to the green indicator light for its push-to-test circuit.
12. c
Relay PCO provides 24-volt DC power from the bus through a 5-amp circuit breaker to the Fuel Pressure Crossfeed Valve Open caution warning light in the cockpit.
If relay PCO fails to operate, contacts 13 will not complete the circuit and the light will not illuminate, but the rest of the system will operate normally.
13. b
The fuel-selector switch must be in the Crossfeed (X-Feed) position for the relay TCO to close contacts 14.
When the tank selector is put in the X-Feed position, contacts 17 of relay FCF close, and current flows from the 24-volt DC bus, through a five-amp circuit breaker, into the “open” coils of the fuel tank X-Feed valve motor.
When the motor opens this valve, contacts 19 close and current flows to relay TCO closing contacts 14.
14. a
When the fuel selector switch is in the right-hand tank position and power is supplied from the bus, three relays (RTS, PCO, and TCC) will actuate.
Current flowing through the fuel-selector switch energizes the coil for relay RTS. This closes contacts 8 and opens contacts 7.
Current from the bus flows through closed contacts 5 of relay LTS, through contacts 8 of relay RTS that has just closed, and through the “open” winding of the fuel pressure X-Feed valve motor.
As soon as this motor fully opens the valve, contacts 12 close and energize relay PCO to close contacts 13 in the circuit for the Fuel Pressure Crossfeed Valve Open light.
Current flows from the bus through the right-hand five-amp circuit breaker and through the normally closed contacts 18 of the FCF relay, through contacts 20 in the Fuel Tank X-Feed Valve to the coil of relay TCC which opens its contacts 16.
15. a
As soon as electrical power is supplied to the 24-volt bus, two relays, PCC and TCC, are energized.
Current flows from the bus through the left-hand, five-amp circuit breaker and through contacts 5, 7, and 9 of the relays controlled by the fuel selector switch. It flows from contacts 9, through contacts 11 in the Fuel Pressure X-Feed valve, to the coil of relay PCC.
At the same time, current flows through the right-hand five-amp circuit breaker, through contacts 18 and then through contacts 20 in the Fuel Tank X-Feed valve to the coil of relay TCC.
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