Test 1 Subject Summaries Flashcards
Cahracteristics of Electricity
- Electricity is the energy made available by the flow of electric charge through a conductor.
- AC is an electrical current that reverses its direction at regularly recurring intervals.
- DC is an electrical current flowing in one direction only and substantially constant in value.
- Magnetism and chemical are two ways that electricity can be produced.
- Field excitation is the production of an electromagnetic field. A generator can be separately excited by current coming from another source. A field excitation current may be carefully controlled by controlling the external excitation current.
- Transformation of voltage is controlled when electricity flows into a coil, which induces a second coil, to give a different output voltage.
- Step-up transformation is when the input coil has less wraps than the output coil. This causes the voltage to increase.
- The conversion of AC to DC is the modification to the phase extremes, removing or to cut off the top and/or bottom of an AC phase results in a one-way current.
- Two types of electrical circuits are a series circuit and a parallel circuit.
Characteristics of the UH 60 AC Electrical System
- The AC electrical system consists of primary AC power, auxiliary AC power, and external AC power.
- The No. 1, No. 2, and the APU generator control units continuously monitor and regulate generator output to provide voltage regulation, current regulation, over-voltage protection, under-voltage protection, feeder fault protection, and under-frequency protection.
- The AC bus tie contactor (K-4) provides three-phase AC power from the APU generator, or external AC power receptacle, to the AC primary buses.
- The current limiters are a 60 ampere fuses protecting the operating generator from excessive overloading during transfer operations.
- On the pilot circuit breaker panel, the AC essential bus transfer (XFER) relay (K-8) provides connection of 115 VAC, B phase power to the AC essential bus.
- The external power monitor panel monitors the external AC input for under-voltage, over-voltage, under-frequency, over-frequency, and correct phase rotation conditions.
- The No. 1 junction box contains the No. 1 generator contactor (K-1), current transformer (T13), autotransformer (T12), current limiters (CL4, 5, 6), and one test receptacle.
Characteristics of the UH 60 DC Electrical System
The primary DC system consists of two converters, supplied from the AC power system, and associated caution/advisory capsules.
- The converters operate from 115/200 VAC, three-phase, 400 Hz power and provide outputs of 31 VDC at no load to 25 VDC at 200 amperes.
- The DC bus tie contactor (K15), on the No. 1 Junction box, provides a connection between the No. 1 and No. 2 primary buses.
- The DC bus tie current limiter (CL7), in the No. 1 junction box, is a 100 ampere fuse that protects the connection between the No. 1 and the No. 2 primary DC buses.
- The current limiter (CL7) operates when one primary DC bus is supplying the other DC primary bus as a result of a converter failure caused by a load short-circuits.
- The DC ESS BUS OFF capsule is illuminated when the charge of the battery supplying the DC essential bus falls to 35% and the bus is dropped off line.
- The battery analyzer/conditioner continuously monitors battery voltage and temperature condition and contains a charging circuit for the battery.
- The battery supplies power to the DC essential bus when no AC power is supplied to the helicopter buses.
UH 60 Electrical Schematics
- The battery always supplies the battery utility bus. The battery analyzer/conditioner continuously monitors battery voltage and temperature condition and contains a charging circuit for battery charging.
- The No. 1 and No. 2 converters receive three-phase AC power from the No. 1 and No. 2 AC primary buses. With both converters operating normally, the No. 1 converter supplies the No. 1 DC primary bus and the No. 2 converter supplies the No. 2 DC primary bus.
- If the No. 1 converter fails and its output drops to zero, No. 1 DC primary bus contactor (K16) de-energizes. DC power from the No. 2 DC primary bus is applied through the normally closed auxiliary contacts of contactor K16 to energize DC bus tie contactor (K15). With contactor K15 energized, DC power from the No. 2 DC primary bus is applied through the 100 amp current limiter to supply the No. 1 DC primary bus.
- The three-phase AC power is applied from the external power receptacle through the normally closed main contacts of contactor K3, the energized main contact of contactor K4, and the normally closed main contacts of contactor K2 to supply the No. 2 AC primary bus. The No. 1 AC primary bus is supplied through current limiters. CL1, CL2, and CL3 and the normally closed main contacts of contactor K1. The No. 1 AC primary bus supplies 115 VAC, B phase power, through the AC ESNTL BUS SPLY circuit breaker, to the coil and contacts of AC essential bus XFR relay K8. With relay K8 energized, and 115 VAC, B phase power is supplied to the AC essential bus. The AC essential bus applies 115 VAC, B phase power to an autotransformer that supplies 26 VAC to navigation instrument loads.
- With the No. 1 and No. 2 generators OFF and the APU generator operating at its rated value, APU/external power contactor (K3) is energized. DC voltage is applied through a blocking diode and the normally closed auxiliary contacts of No. 2 and No. 1 generator contactors (K2 and K1), to energize AC bus tie contactor (K4). The three-phase AC output of the APU generator is applied through the energized main contacts of contactors K3 and K4, and the normally closed main contacts of contactor K2, to supply the No. 2 AC primary bus. The No. 1 AC primary bus is supplied through current limiters and the normally closed main contacts of contactor K1.
- When the generator control switch is placed to TEST, system operation is the same as for the ON position, except that generator contactor K1 remain de-energized. Power from the GCU flows through the normally closed contacts of K1, to illuminate the No. 1 Generator capsule on the Caution/Advisory Panel. The GCU test relay, which is located inside the GCU, is energized. With the GCU test relay energized, its contacts open and the caution/advisory panel GEN capsules go off. The generator outputs are not applied to the AC buses, but are applied to the test receptacles for monitoring.
- If the No. 1 generator fails, the No. 2 generator supplies the No. 1 AC primary bus through current limiters and the normally closed main contacts of No. 1 generator contactor (K1).
- With No. 1 GENERATORS switch OFF, the No. 1 generator output does not build up. The No. 1 generator contactor (K1) is de-energized, and voltage flows through the normally closed auxiliary contacts of K1 to illuminate the No. 1 GEN capsule on the caution/advisory panel. The three-phase output of the No. 2 generator is applied from the No. 2 AC primary bus, through current limiters CL1, 2, and 3, and through the normally closed main contacts of the No. 1 generator contactor (K1), to supply the No. 1 AC primary bus. With the failure of the current limiters 1, 2, and 3, voltage is unable to flow from the No. 2 AC Primary Bus to supply the No. 1 AC Primary Bus.
- If a failure occurs to the AC essential bus, the AC ESS BUS OFF capsule on the caution/advisory panel will light. Also, voltage will be removed from the 26 VAC bus.
Function of the UH 60 Hydraulic System
(1) There are three hydraulic systems on the UH-60 helicopter: No. 1, No. 2, and the Backup system.
(2) The No. 1 system services the first stage of the primary servos and tail rotor servo.
(3) The No. 2 system services the second stage of the primary servos and pilot assist module.
(4) The backup will pressurize the No. 1 and No. 2 hydraulic systems, the APU accumulator, and the 2nd stage tail rotor servo.
Function of the UH 60 Hydraulic System 2
a. Each of the systems has a pump/reservoir combination.
b. The Transfer module connects hydraulic pressure from the pump module to the flight controls.
c. The primary servo provides a power boost to the main rotor flight controls.
d. The tail rotor servo furnishes a power boost to the tail rotor flight controls.
e. The pilot assist module reduces pilot work load by providing control boost, stick trimming, stability augmentation, and control inputs from the AFCS.
f. The APU start system supplies a hydraulic charge to the APU start motor.
g. The leak detection/isolation system protects the flight control hydraulic system by preventing the further loss of hydraulic fluid in case of a leak.
Instrument Warning
ØThe instrument display system (IDS), used in conjunction with engine and subsystem sensors (temperature, pressure, torque, fuel and RPM), provides the pilots with engine and subsystem monitoring.
ØThe Signal Data Converter (SDC) processes sensor signals and provides proportional digital signals in a multiplexed format to the Central Display Unit (CDU) and the Pilot Display Unit (PDU).
ØThe Pilot Display Unit (PDU) receives signal and power inputs from an associated Signal Data Converter (SDC) and Central Display Unit (CDU). The PDU contains five analog vertical scale displays, two digital displays, three indicator lights and a photocell.
ØThe Central Display Unit (CDU), receives signal and power inputs from both the No. 1 and No. 2 Signal Data Converter (SDC). The CDU contains twelve analog displays, five digital displays, and two failure lights.
ØEngine mounted sensors include the Engine Power Turbine Speed (Np) sensor, alternator, engine oil temperature sensor, engine oil pressure transmitter, engine torque overspeed sensor, and Turbine Gas Temperature (TGT) inputs from the thermocouple harness.
ØThe No. 1 and No. 2 eng gas generator speed indicating signal (Ng) is sent from the alternator to the No. 1 and No. 2 SDC panel. The #1 ENG OUT capsules will be illuminated whenever the No. 1 or the No. 2 engine gas generator tachometer is less than 55%.
ØMultiplexing is the combining of two or more signals for transmission over a shared wire. The signals are combined at the transmitter by a multiplexer and split up at the receiver by a multiplexer.
ØThe NO. 1 or the No. 2 ENGINE OIL TEMP capsule will be on whenever the No. 1 or the No. 2 engine oil temperature is more than 150 °C.
ØSensors that are not multiplexed are the Fuel, XMSN Oil Temp and XMSN Oil PSI sensors.
Instrument Warning 2
ØThe low rotor RPM warning is disabled with weight on wheels.
ØThe caution/advisory panel gives visual indications, on aviation yellow or green color-coded capsules, that show the status of as many as 82 helicopter subsystem conditions.
ØThe audible warning function is controlled by the left relay panel.
Ø Warning signals from the IDS (low rotor RPM and No. 1 or No. 2 engine out) and the stabilator system are routed through the left relay panel to activate the audible warning unit, which generates both beeping and steady warning tones.
ØWith a low rotor RPM warning condition present during flight (Nr is less than 96 %), a signal is applied through the contacts of relay K46 to the audible warning unit. The steady warning signal is then applied to the pilot and copilot stations.
ØDuring the replacement of any Master Warning Panel capsule parts ensure that all electrical power is off.
ØThe dimming system consists of relays K40 and K43 as well as dimming resistors R8, R9, and R10 in the left relay panel, a LIGHTED SWITCHES dimmer control on the upper console, indicator lights dimmer forward of the lower console, pilot and copilot RAD ALT DIMMING controls on the instrument panel, and the BRT/DIM-TEST switch on the caution/advisory panel.
ØMTF checks include Bright/Dim Test, Caution/Advisory panel dimming, CDU/PDU test, Photo cell sensitivity test, Stabilator audio warning priority, Engine oil pressure, and Low rotor off at 96% Nr, Engine out light on below 55% Ng.
