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To control the drive output speed thereby control generator frequency, and equalize the load between generators during parallel operation.
If CSD output rotation drives the generator below 365 Hz, what component causes the generator to be removed from the bus?
If the CSD temperature rises to an overheat condition, what should be done to prevent further
Differential fault protection, individual phase-sensing, reactive-biasing, current-sensing, voltage-regulation, paralleling, and underfrequency protection.
The No. 2 generator is powering the No. 2 main AC bus. Voltmeter readings are 28 VDC out of
the GCU, 28 VDC at the input to the coil of the BTC, and 28 VDC on the ground of the BTC. Why would the No. 2 BTC OPEN light remain on?
RBC, neutral current, and unbalanced current.
When No. 1 GCS is in the TEST position, there are voltmeter readings on both sides of the GCS
and an ohmmeter of infinity through the generator exciter field. Why would the system voltmeter and frequency indicate zero?
Before two generators can be paralleled, the comparative potential of the generators and tie bus must be within what tolerances?
The hydraulic solenoid is deenergized and the emergency generator is on.
Three-phase from the main generator or external power.
During an aircraft sortie, the emergency generator was put on-line because of a main generator
system malfunction. When the aircraft landed, the emergency generator dropped off-line. What is the probable malfunction?
What component of the external power system provides a means of connecting external AC
power to the aircraft systems?
When the external power unit is supplying correct power and that power can be applied to the
aircraft, what indication is visible?
Allow current to flow in one direction through the circuit and to prevent the TR output from being connected to the aircraft buses.
During a main DC power loss, what components prevent the batteries from powering buses other than the battery and emergency buses?
The RCRs will deenergize and prevent the batteries from powering other buses other than the battery and emergency buses.
What causes all internal relays inside an RCR to deenergize?
The limit switches halt power to the actuator drive unit.
What position would the stabilizer trim cutout switch be in to deactivate the stabilizer trim safety relay?
What could result if the pilot’s and copilot’s trim control switches are actuated in opposite
How many minutes of actuator cooling time are necessary for two minutes of operating time?
In what direction does the leading edge of the horizontal stabilizer move when the control switch is put in the NOSE DN position?
Referring to figure 2–1, what component is defective if there is no voltage at terminal B1 of the
pilot’s stabilizer trim control switch?
Referring to figure 2–1, you find that you have voltage at terminal No. 8 on terminal board RT-
16, but none on the up-side of the actuator drive unit. What component is most likely defective?
What is used to control the aileron trim motor?
What two switches can be used to stop the aileron trim motor?
The stick grip trim switch and aileron trim motor limit switch.
In what position are the ground-air safety relay switch contacts if the aircraft is on the ground and the power is on?
In what position should all switches and controls be placed before aileron trim assembly ground power supply is turned on?
How do wing flaps shorten landing and take-off roll?
28 VDC is removed from solenoid 2 of the speedbrake control valve and the speedbrakes maintain their current position.
During flight and with the landing gear extended, at what angle are the speedbrakes automatically limited?
Automatically by a compressor in the aircraft.
By gas turbine or auxiliary power unit (either ground or airborne) or bleed air from the compressor of another engine.
When high-pressure air is connected to the pressure side of a pneumatic starter and the
regulating-and-shutoff valve is closed, where does the pressure go?
It is vented overboard to prevent the starter from operating.
Energizing what component allows pneumatic starter pressure to be vented to the top of the valve actuator?
to keep air pressure on the turbine wheel constant and to maintain the desired starter speed.
What is the purpose of the C-135 engine ignition circuit?
Know normal system operation.
What is the final step in troubleshooting?
Perform a final operational check
What should you use to check the wiring between the ignition control unit and the igniter plug? Why?
An Ohm meter, because the igniter’s extremely high voltage makes it unsafe to check for voltage. You must remember to disconnect power before making this check.
If the GTC starts and operates all right, but the start light does not come on, what is the probable
What problem is indicated if the on-speed light does not come on when the GTC is operating
normally and the light bulb is good?
What type of motor drives the boost pumps in the fuel system?
205 VAC, 400-Hz, 3 phase induction motor.
To admit fuel into each tank during fuel servicing and to automatically shut off fuel-flow when the tank is full (by either weight or volume).
No-fuel-flow during engine fuel feeding.
What indicates that the fuel quantity in the outboard wing and/or external tanks is at an unsafe level?
When refueling the aircraft from the single-point refueling receptacle, in what position must the master switch and the refuel valve control switch be placed?
To determine whether the pump discharge pressure at no-flow for the main tank and auxiliary tank boost pumps is within the permissible range.
Scavenge pump, shutoff valves, float switch, control switch, and amber FUEL IN MANIFOLD indicating light.
They provide specifications, tolerances, torque valves, troubleshooting charts, part numbers, and wiring diagrams.
When troubleshooting the fuel boost pump with an ohmmeter, what reading should you expect?
The fuel boost pump itself should read infinity on the ohmmeter; readings for each of the phases should be within a maximum spread of 10 ohms.
On conventional aircraft they are placed in the engine and baggage compartments. On jet aircraft they are placed on the engine section, nacelle, or tail cone.
What type of unit is a thermal switch? How does it operate?
It’s a heat-sensitive unit. It completes an electrical circuit when exposed to a specified temperature.
When subjected to heat, both the shell and internal elements expand and subsequently increase their overall length. However, the increase in the length of the shell, which has a high coefficient of expansion, is much greater than the expansion of the internal elements in the assembly; this forces the switch contacts to close.
(1) Be cautious when handling these units because the shell is the actuating mechanism. Never handle the shell with pliers or force the switch into position either by hand or with tools.
(2) Before, during, and after installation take precautionary measures to ensure that the shell is not dented, distorted, or otherwise damaged.
How are the thermocouples connected in respect to each other?
When the temperature rises rapidly enough, the thermocouples will produce a voltage. This causes current to flow in the circuit that energizes the sensitive relay, which, in turn, closes the slave relay and completes a circuit to the warning light.
Why is it important that polarity check be made of a thermocouple that’s in the fire and overheat warning system?
A reversed thermocouple will not only fail to operate the system, but it will also have a tendency to counteract the output of other correctly connected thermocouples.
How can you distinguish the fire warning light from the overheat light in the photoelectric fire
A rise in ambient temperature causes the resistance between the center conductor and the outer conductor of the sensing loop to decrease. The resistance of the sensing loop is part of a bridge circuit; once the bridge circuit becomes unbalanced due to a change in resistance, current will flow causing the warning light to illuminate.
What component in the caution light circuit causes individual lights in the circuit to dim?
To monitor various systems in the aircraft and warn the pilot of improper positioning of the flight controls prior to take-off.
(1) Cargo doors;
(3) Thrust reversers;
What components comprise the take-off warning system?
When troubleshooting a problem with the take-off warning system, what action should you take
after completing the operational check?
Use extreme care when working with any type of voltage. A small amount of voltage can be as deadly as a large amount.
Which component has the responsibility to coordinate the flow of information on the data bus?
(1) The space and weight requirements for the system decreases;
(2) The reliability and maintainability of the system increases;
(3) The performance of the overall integrated system increases proportionate to the number of systems integrated;
(4) The cost of the overall program decreases.
With the aircraft in the proper configuration, what do you do to make the landing gear go to either the up or down position?
Right and left MLG hydraulic motors, unlock side of the NLG up-lock cylinder, and the NLG-actuating cylinder.
What two conditions must be satisfied before electrical power can be applied to the up solenoid on the landing gear selector valve?
The landing gear is not down and locked and any throttle is retarded below minimum cruise power, and the landing gear is not down and locked and the wing flaps are less than 75 percent extended.
What feature of the lock-in circuit permits the warning horn to sound off another time if a second throttle goes below cruise speed?
To check out a faulty landing gear system, what two steps should be initiated prior to performing an operational check?
Replace the position indicator.
If you have the problem where all essential 28 VDC bus systems work
satisfactorily, but sometimes you have intermittent power when raising or lowering the landing gear, what do you check?
Make sure that (1) there is a good firm connection at the LG control (on the DC bus), (2) the circuit breaker was operating OK and had good connections, (3) the wire to the landing gear control switch was not faulty, (4) there is a good connection to the landing gear control switch, (5) the landing gear control switch and its contacts are functioning properly.
How is the frequency of the transducer governed?
By the wheel speed.
For what two reasons is the output signal from the wheel transducer formed into a square wave in the circuit card control channel?
What circuit provides for a gradual application of brake pressure after a skid condition has
If the locked-wheel memory circuit is activated and any wheel stops rotating, what component
will relieve brake pressure to that wheel?
How does the touchdown protection circuit prevent brake application when the gears are down and locked, but no weight is on the gears?
By applying 28 VDC to the locked wheel circuit through the nose gear warning relay and main gear safety switch.
The test circuit.
What circuit produces a nearly constant output, regardless of the variations in the airplane power supply?
An operational check of the system.
What are the four types of circuits contained in the steering control box?
What type of switch is used for the NLG weight-on-wheel switch?
Once the aircraft is airborne, as the gear starts to retract and the NLG DN AND LOCK switch
opens, what is deenergized? What happens to the electrical power from the control box?
What switch will turn on the NWS system only if the NLG weight-on-wheels switch is closed?
The NWS A/R DISC MISL step switch.
How does the NWS system remain energized after the NWS A/R DISC MSL step switch is
If the pilot disengages the NWS system by depressing the NWS step switch and relay K1 remains energized, what would never happen?
What happens when the pilot needs to make a right turn and depresses the right rudder pedal
The wiper arm of the command potentiometer moves up, decreasing the amount of output voltage on pin C (steer-left error-sensing circuit) of the control box.
What happens when the pilot needs to make a left turn and depresses the left rudder pedal
The wiper arm of the command potentiometer moves down, increasing the voltage signal to pin C (steerleft error-sensing circuit) of the control box.
. In NWS system operation, when is hydraulic pressure sent to the steering actuator to turn the nose gear?
Error-sensing circuit, 120-ohm control module relays A and B, NWS malfunction relays (K6 and K7), and fail-safe circuit.
What purpose does the steering control valve serve?
How is the rudder pedal nose-steering control relay energized?
Because the amount of lighting required by the aircraft is partially determined by the number of crew members and size.
How do the landing and taxi lights differ in overall purpose from the formation lights and position lights?
Landing and taxi lights are designed to provide illumination on other objects. Position and formation lights are designed to attract attention or to be seen; they are used to indicate an aircraft’s position or heading to other aircraft at night.
What feature in the nose gear landing light circuit in most aircraft prevents the landing light from being turned on accidentally?
Why are some navigation lights switched from a bus that provides 28 VAC to a bus that has only 14 VAC applied to it?
What opens and closes the flasher contacts to cause the taillight to flash on and off?
To attract the attention of nearby aircraft to prevent collisions.
What component converts 28 VDC to 400 VDC to provide a trigger voltage for the strobe anti-collision lights?
What is the purpose of the lightning suppressors?
To route any power surge over 600 [±90] VDC to ground and prevent damage to the anti-collision lights and aircraft power sources.
Explain the function of the bulb filaments in the lights in the fuselage light system discussed in this lesson.
The higher wattage filament is energized for bright lights; the lower wattage filament is energized for dim lights.
How does a tanker aircraft produce a coded signal for aircraft attempting a rendezvous for air
By controlling the color and beam from the rendezvous lights.
When checking a circuit with an ohmmeter, why must the section being checked be isolated from the rest of the circuit?
If the ramp failed to operate with the control switch set to OPEN, what is most probably
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