What are the three generators that make up a brushless AC generator?
a. PMG, AC exciter, and main AC.
What are the two main components of an AC generator?
a. Rotor assembly and stator.
What three components make up the stator?
a. PMG armature, exciter field, and main armature windings.
What are the two functions of the CSD governor system?
a. 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 damage?
a. Disconnect the CSD.
What are the seven types of protection provided by circuitry inside the GCU?
a. 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?
a. Open BTC ground.
What three types of "protection" circuits are used only during parallel operation?
a. 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?
a. Open generator exciter field.
Before two generators can be paralleled, the comparative potential of the generators and tie bus must be within what tolerances?
a. Frequency within 0.1 to 12.0 Hz and voltage phase angle difference less than 90 degrees.
When the hydraulic solenoid valve is energized, what is the status of the emergency generator?
a. The emergency generator is off.
What happens when the emergency generator test switch is placed to the TEST position?
a. The hydraulic solenoid is deenergized and the emergency generator is on.
What power source energizes the EPDR?
a. C-phase of the emergency generator.
What power source energizes the PFR?
a. Three-phase from the main generator or external power.
Which buses are powered by the emergency generator?
a. Just the essential bus.
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?
a. The EPIR.
What component of the external power system provides a means of connecting external AC power to the aircraft systems?
a. External power receptacle.
What does the BPP provide?
a. Protective and control functions during external power use.
What external power BPP component will prevent power from being applied to the power selector switch when voltage is less than 103 [±3]?
When an overvoltage condition exists, what is the external power system time delay?
a. Inversely proportional to the amount of overvoltage above 130 VAC.
When the external power unit is supplying correct power and that power can be applied to the aircraft, what indication is visible?
a. READY light will illuminate on the flight engineer's control panel.
What APU component opens above 365 Hz to allow the USR to energize?
What three internal components make up the TR?
a. Cooling fan, step-down transformer, and diode bank.
For the internal cooling fan to operate, what must be provided to the TR?
a. 115 VAC input.
What are the two functions of an RCR?
a. Allow current to flow in one direction through the circuit and to prevent the TR output from being connected to the aircraft buses.
Why is it beneficial to have a paralleled TR system?
a. Because it provides a means of supplying DC power in the event one T/R fails.
What is the result if the 400-ampere current limiter is open?
a. System would not parallel and one TR unit could not power the entire system.
During a main DC power loss, what components prevent the batteries from powering buses other than the battery and emergency buses?
a. The RCRs will deenergize and prevent the batteries from powering other buses other than the battery and emergency buses.
What voltage is required to energize the coil of the voltage relay inside an RCR?
a. Any voltage above 22 VDC.
What causes all internal relays inside an RCR to deenergize?
a. When the potential at the load is higher than that of the TR units.
What is the result if one input phase to a TR unit is low?
a. TR unit would have low output voltage.
What happens when the stabilizer is moving to 14 degrees below the horizontal plane?
a. The limit switches halt power to the actuator drive unit.
What are used to regulate the direction of the stabilizer trim screw?
a. Electronically controlled clutches.
What is the purpose of the disconnect clutch in the stabilizer trim actuator assembly?
a. To disconnect the power actuator in the event of actuator jamming or binding.
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 directions?
a. Either excessive wear of the ball detent clutch or stalling of the motor.
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?
In what position do you leave the stabilizer cutout switch after the operational check is complete?
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?
a. The stabilizer trim cutout 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?
a. The NOSE DN limit switch.
What would an infinity reading at pin H of the actuator drive unit connector plug tell you?
a. You have an open ground.
What component is used as the normal means of aileron trim control?
a. The control stick grip trim switch.
What component tells the pilot when the ailerons are in the take-off position?
a. The take-off trim indicator lights.
What is used to control the aileron trim motor?
a. The trim switch on either the top of the control stick grip or on the trim panel.
What components are driven by the trim motor?
a. Trim actuators.
What two switches can be used to stop the aileron trim motor?
a. The stick grip trim switch and aileron trim motor limit switch.
What is the purpose of the right and left dual spool valves?
a. They direct hydraulic flow and pressure to the ailerons.
Will the control stick move after trim is initiated?
a. No, it will be the same as it was when the trim was initiated.
How long will the indicator light remain on after the trim switch is released?
a. It will extinguish as soon as the switch is released.
In what position are the ground-air safety relay switch contacts if the aircraft is on the ground and the power is on?
Can the take-off trim indicator lights operate with the aircraft airborne?
a. No, because of the landing-gear-actuated ground air safety switch.
What two systems should be supplied with power before the aileron trim assembly is operated?
a. The electrical and hydraulic systems.
In what position should all switches and controls be placed before aileron trim assembly ground power supply is turned on?
What position should the left aileron be in if the right aileron is down?
How do wing flaps shorten landing and take-off roll?
a. By increasing the lift effect.
What are the two types of flaps used on heavy aircraft?
a. Slotted and Fowler.
What do the slotted flaps eliminate?
a. Some of the undesirable stall characteristics.
Describe how the Fowler flaps are constructed?
a. The lower surface of the trailing edge rolls back on tracks.
What do fighter aircraft use leading edge slats?
a. They automatically reduce the stall characteristics.
How are the speedbrakes controlled?
a. By a three-position switch located on the throttle grip.
After the speedbrakes are extended, what happens when the speedbrake switch is released?
a. 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?
a. 43 degrees.
Where must power be applied to cause the speedbrakes to remain in the HOLD position?
a. Solenoid 1.
From what source does the fuel-air starter get its supply of fuel?
a. From the aircraft engine supply.
At about what percent of engine speed will the fuel-air starter turn the engine?
a. At about 35 percent.
When the engine reaches 35%-RPM, what stops the starter?
a. A set of centrifugal switches on the starter.
How is the fuel-air starter air bottle recharged?
a. Automatically by a compressor in the aircraft.
When does the heater in the air moisture separator operate? Why does it operate?
a. At 40°F. To prevent freezing of any water that may collect in the air moisture separator.
What is the effect of an open centrifugal switch in the pneumatic starter system?
a. It breaks the ground circuit to the start relay solenoid and the turbine rotor stops rotating.
What are the two sources of air that are supplied to the pneumatic starter?
a. 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?
a. 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?
a. The starter valve solenoid.
What are the two purposes of the regulator valve in a pneumatic starter?
a. To keep air pressure on the turbine wheel constant and to maintain the desired starter speed.
What components make up the AC ignition system?
a. Ignition relay, ignition switch, ignition transformer, high-ratio transformer and inverter.
About how many volts does the AC ignition deliver to the igniter plug?
What are the three main components of a DC ignition system?
a. Vibrator, transformer, and igniter plug.
What function does the vibrator unit in the DC ignition system perform?
a. Changes 28 volts DC to pulsating current.
What is the purpose of the C-135 engine ignition circuit?
a. To ignite the fuel and air mixture in the engine, and to ensure continuous combustion while the aircraft is in flight.
How many high-energy sparks are produced by the C-135 engine ignition circuit each second?
What can the high-energy sparks produced by the C-135 circuit do other than vaporize fuel?
a. Blast away carbon deposits from the center electrode of the spark igniter.
What is the first step in troubleshooting?
a. Know normal system operation.
What is the final step in troubleshooting?
a. Perform a final operational check.
What should you use to check the wiring between the ignition control unit and the igniter plug? Why?
a. 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 cause?
a. A burned out light bulb.
If the start-and-ignition hold relay is defective, could you start the GTC up to 5-percent speed?
a. No. The GTC starter relay gets its power across the contacts of the energized start-and-ignition hold relay.
What problem is indicated if the on-speed light does not come on when the GTC is operating?
a. A defective 95 percent speed switch.
What type of motor drives the boost pumps in the fuel system?
a. 205 VAC, 400-Hz, 3 phase induction motor.
What type of valve is generally used as a fire shutoff valve?
a. Motor-driven, sliding gate.
What type valve is generally found on the auxiliary tank engine feed control?
a. Rotary plug.
What are the two purposes of the fuel-level control valve?
a. 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).
When you get a flashing amber light on the fuel-flow indicator, what condition exists?
a. No-fuel-flow during engine fuel feeding.
When you get a steady amber light on the fuel-flow indicator, what condition exists?
a. A closed fuel control valve during refueling.
What indicates that the fuel quantity in the outboard wing and/or external tanks is at an unsafe level?
a. A red indicator light adjacent to applicable tank.
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?
a. With the master switch ON and refuel valve control switch OPEN.
What is the purpose of the boost pump pressure checkout circuit?
a. To determine whether the pump discharge pressure at no-flow for the main tank and auxiliary tank boost pumps is within the permissible range.
What is the purpose of a fuel scavenge system?
a. To remove fuel trapped in the refuel manifold and the main manifold.
What components make up the scavenge system?
a. Scavenge pump, shutoff valves, float switch, control switch, and amber FUEL IN MANIFOLD indicating light.
What is the approximate output of the fuel scavenge pumps?
a. 2 gpm.
What switch directly controls each fuel scavenge pump?
a. A float switch in the scavenge drain line.
How do TOs aid you when you're troubleshooting?
a. 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?
a. 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.
Where are fire detectors normally placed on aircraft?
a. 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?
a. It's a heat-sensitive unit. It completes an electrical circuit when exposed to a specified temperature.
How are the thermal switches connected?
a. Connected in parallel with each other, but in series with the warning light.
How do the FENWAL® and iron fireman detector switches operate?
a. 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.
What are two precautions you must take when handling thermal switches?
a. Any two of the following: (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, (3)Use caution in securing the lock washer and hex nut on the positive terminal of the switch. When securing the terminal nut, use a torque wrench. Check current technical data for proper torque values, (4)Upon installation of a new switch, inspect the outer shell visually for evidence of any damage that could change the actuating point or prevent the switch from operating, (5)After the switch has been put into operation, always keep it free of dirt, dust, oil, grease, or any foreign substance that may accumulate on the switch and change the amount of heat required to actuate it, (6)Different locations on the aircraft require different heat ranges, so be certain that you install the correct type. The type number of the detector switch can be located on the unit's mounting flange.
Who can adjust the fire and overheat detector switches?
a. Maintenance personnel.
What causes a thermocouple fire detector system to activate?
a. Rate of temperature rise.
What three components are in the relay box of a thermocouple fire warning system?
a. Sensitive relay, slave relay, and thermal test unit.
How are the thermocouples connected in respect to each other?
a. In series.
How does the thermocouple operate in a warning system?
a. 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. 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.
What is used to check the polarity of thermocouples?
a. The lowest amperage or voltage scale on a multimeter.
To what frequencies is the amplifier of a photoelectric fire detection system sensitive?
a. Between 7 and 60 Hz.
How can you distinguish the fire warning light from the overheat light in the photoelectric fire detection system?
a. The overheat light flashes, and the fire warning is steady.
How does the sensing loop in a continuous loop fire warning system operate?
a. 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.