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Part 4 Systems > Erics final flyover > Flashcards

Erics final flyover Flashcards

1
Q

What is the function of the electrical system on a large aircraft?
What are the differences between light and large aircraft electrical systems?

A

GENERATE, REGULATE and DISTRIBUTE electrical POWER;
MORE THAN 1 system for REDUNDANCY;
Normal CONFIG will have seperate AC CIRCUIT powered by ALTERNATOR fitted to each ENGINE and each CIRCUIT feeds specific BUS;
AC more COMMON as it is LIGHTER

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2
Q

What are buses?
What is their purpose?
What type of buses are likely to be used

A

POWER is ROUTED to a common bar off which SEVERAL COMPONENTS or SERVICES can be powered;
This means systems can be PRIORITISED for the use of ESSENTIAL SERVICES in event of SUPPLY BREAKDOWN;
PARALLEL, SPLIT, or SPLIT-PARALLEL

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3
Q

How is DC provided when AC is present?

Are they separated?

A

AC is RECTIFIED using FULL WAVE RECTIFIER;

DC has own BUS SYSTEM ISOLATING entirely from AC

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4
Q

How can AC be produced from DC in emergency?

A

Operating an INVERTER or STATIC INVERTER from DC BATTERY

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5
Q

What is the purpose of a CSD?

Why do we need this?

A

CONSTANT SPEED DRIVE;
To keep the AC GENERATOR at a CONSTANT SPEED and PRODUCE CONSTANT 400Hz +/-8Hz;
Frequency of power out of alternator is determined by ROTATION of ARMATURE which is DRIVEN by ENGINE that is VARIABLE usually between 7000-10000RPM so CSD is used

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6
Q

What is the most commonly used CSD

A

HYDRO MECHANICAL device which uses MECHANICAL GOVERNORS

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7
Q

What will happen to the CSD if an electrical fault occurs?

What about an overheating or mechanical problem?

A

Electrical fault: CIRCUIT BREAKERS;
Overheat/mechanical: ROTATION must be STOPPED FIRST through the use of a GUARDED SWITCH labelled “GEN DISC” activates a SOLENOID which pulls a DOG CLUTCH OPEN that BREAKS the DRIVE between GEARBOX and CSD. It CANNOT be RESET

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8
Q

What does Boeing and Airbus call their respective CSDs?

A

Boeing: INTEGRATED DRIVE GENERATORS;
Airbus: INTEGRATED CONSTANT SPEED DRIVE`

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9
Q

What are most modern constant frequency AC generating systems fit with?

A

ROTATING RECTIFIER, BRUSHLESS, AC GENERATORS

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10
Q

How is an AC generator excited?
What is the power output of an AC generator usually?
WHat are they power rated to?

A

SELF, PILOT or EXTERNALLY;
115VAC, 400Hz 3 PHASE;
20-60kVA

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11
Q

What is the advantage of having a 3 phase AC generator?

Does this come with any disadvantages?

A

INCREASES CURRENT AVAILABLE, therefore, POWER available;
Connection to PHASE sensitive equipment such as 3 PHASE MOTORS and TRANSFORMERS are CRITICAL;
INCORRECT PHASE sequence in MOTOR causes ROTATION in the OPPOSITE direction;
INCORRECT PHASE sequence in 3 PHASE MOTOR and TRANSFORMER in PARALLEL could cause BURN OUT`

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12
Q

What is the purpose of the cabin air conditioning and pressurisation system?
What does this specifically cover?

A

TO provide a means of TEMPERATURE, HUMIDITY, and VENTILATION control;
PAX COMFORT;
AVOID CONDENSATION on AVIONICS equipment due to HEAT build up;
DOMESTIC ANIMAL COMFORT in CARGO

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13
Q

What are the sub-sections of the passenger environment systems?
What is their collective purpose?

A 
PRESSURISATION;
AIR CONDITIONING;
HEATING;
OXYGEN;
PRESSURE CELL;
Supply INHABITED areas with TEMP control and safe atmospheric PRESSURE/OXYGEN at ALTITUDE
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14
Q

What is the definition of PD?

How is PD controlled throughout the flight?

A

DIFFERENCE in PRESSURE between INSIDE HULL and AMBIENT at ALTITUDE flying;
Will regulate PRESSURE to 8000ft due to HYPOXIA regardless of aircraft altitude so PD INCREASES with ALTITUDE;
PD is built up by controlling the OUTFLOW to be LESS than the INTAKE through AIRCON when OPTIMUM PD is achieved INFLOW = OUTFLOW;
The VERTICAL SPEED is also controlled by RATE CONTROLLER to ensure PAX COMFORT

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15
Q

How does cabin altitude change?

How is the cabin altitude/vertical speed controlled?

A

As ALTITUDE INCREASES so does CABIN ALTITUDE but at a LOWER RATE, usually in 1000s of FT/MIN;
By OUTFLOW VALVE, controlled by CREW SETTINGS to maintain safe PSID

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16
Q

What are the requirements of an air conditioning system?

A

PRESSURE CELL designed to WITHSTAND PD;
Can respond to RAPID CHANGES in AMBIENT PRESSURE/TEMP;
Air SUPPLY sufficient for cabin PRESSURISATION and AIR CONDITIONING

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17
Q

What are the components of cooling units?

A

PRIMARY HEAT EXCHANGER;
SECONDARY HEAT EXCHANGER;
REFRIGERATION UNIT

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18
Q

What is the purpose of primary/secondary heat exchangers and refrigeration unit?

A

PRIMARY: COOL COMPRESSED AIR bled directly from ENGINE COMPRESSOR to typical TEMP (300F);
SECONDARY: COOL AIR further so REFRIGERATION UNIT operate EFFICIENTLY;
REFRIGERATION: Provides AIR at TEMP appropriate for necessary CABIN COMFORT expected of AIRCON

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19
Q

How is distribution achieved in environmental control?

A

Via DUCTS and DIFFUSERS

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20
Q

What are the characteristics of duplicated environmental systems?
What will occur if one engine-driven system fails?
What will occur if both engine-driven systems fail?

A

Each system may FEED from ONE ENGINE;
Each system may feed to DIFFERENT AREAS ie: COCKPIT/AVIONICS BAY/ONE SIDE of CABIN and BAGGAGE COMPARTMENT/REST of CABIN;
Operation is still SATISFACTORY and often utilised in HIGH POWER conditions such as HIGH ALT RUNWAYS/HEAVY ICING/HEAVY TAKEOFFS;
Fresh air is provided through the ALTERNATE RAM AIR

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21
Q

How much of the air is recycled in an environmental control system?
What is the purpose of recycling?

A

50% of CABIN AIR;

REDUCE LOAD on air DELIVERY system, especially when AIR is drawn from ENGINE COMPRESSORS

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22
Q

What are the 3 positions that control the environmental system?
How may this differ in modern aircraft?

A

OFF, NORMAL, RAM;

Modern have panels where TEMPERATURE may be SET and INDICATED along with DIFFERENT temperatures in CABIN and COCKPIT

23
Q

What instrumentation is connected to the control of the environmental system?

A 
Cabin PRESSURE CONTROLLER;
RATE SELECTOR;
LANDING ALTITUDE SELECTOR;
BAROMETRIC PRESSURE SELECTOR;
EMERGENCY CONTROLS;
WARNING LIGHTS;
APU
24
Q

What are the safety features of the pressurisation system?

Briefly describe each one?

A

PRESSURE RELIEF valve: AUTOMATICALLY ensures PRESSURE does NOT build up beyond MAX OPERATING PRESSURE;
NEGATIVE PRESSURE valve: AUTOMATICALLY ensures PRESSURE OUTSIDE CABIN NEVER EXCEEDS INSIDE;
EMERGENCY DEPRESSURISATION valve: Operated by WOW or COCKPIT CONTROL panel when there is EMERGENCY CABIN ALTITUDE control

25
Q

What are the components of the temperature control system?

A 
CABIN TEMP controller;
TEMP SELECTOR knob;
TWO POSITION TEMP control SWITCH;
MODULATING BYPASS VALVE;
CONTROL NETWORK
26
Q

What happens when the temperature control system is switched to the “auto” position?

A

BYPASS VALVE seeks a VALVE GATE position so that DUCT TEMP equals TEMP CONTROLLER SETTING;
CONTROL NETWORK sends SIGNALS from SENSING ELEMENT to CABIN TEMP CONTROLLER which then ELECTRICALLY positions VALVE

27
Q

What happens when the temperature control system is switched to the “man” position?
What

A

CONTROLLER controls BYPASS VALVE DIRECTLY without reference to DUCT TEMP;
Desired TEMP is maintained by MONITORING AIR TEMP KNOB as varying conditions alter CABIN TEMP

28
Q

What is the extended purpose of the primary heat exchanger?
How is it cooled?
How is it controlled?

A

REDUCES the TEMP of ENGINE BLEED AIR or SUPERCHARGER DISCHARGE AIR by routing it through VEINS in CORE of HEAT EXCHANGER;
Cooled by RAM AIR;
Controlled by primary heat exchanger BYPASS VALVE

29
Q

How does vapour cycling work?

A

Refrigerant ABSORBS HEAT from the CABIN and CHANGES STATE from LIQUID to GAS WITHOUT changing TEMPERATURE;
HEAT is taken OUTSIDE of aircraft and given to OUTSIDE AIR then REFRIGERANT returns to LIQUID;
CYCLE is CONTINUOUSLY REPEATED

30
Q

What is the most common material used as refrigerant?

What properties make it desirable?

A 
DICHLORODIFLUOROMETHANE/REFRIGERANT-12;
STABLE at HIGH and LOW TEMPERATURES;
Does NOT REACT with MATERIALS of AIRCON;
Does NOT ATTACK RUBBER HOSES or SEALS;
COLOURLESS and ODOURLESS
31
Q

How much oxygen is usually carried by most transport aircraft?

A

Enough so that aircraft can DESCEND from CRUISE to 14000ft in LESS than 4 MINUTES WITHOUT EXHAUSTING OXYGEN supply

32
Q

What are the advantages and disadvantages of the chemical oxygen system compared to gaseous oxygen systems?

A

Advantages: LIGHTWEIGHT, LESS EQUIPMENT, LESS MAINTAINANCE;
Disadvantages: FIRE HAZARD higher, NOT TAMPERPROOF, WON’T TURN OFF

33
Q

What are the arrangements of passenger oxygen system?

How and where is the oxygen supplied from?

A

SERIES of PLUG-IN supply SOCKETS fitted to CABIN WALL adjacent to seats which MASKS can be CONNECTED OR;
DROP-OUT MASK arrangement which presents masks AUTOMATICALLY if PRESSURISATION FAILS;
AUTOMATICALLY (BARO control VALVE) from MANIFOLD but can be OVERRIDDEN MANUALLY by CREW

34
Q

How much oxygen is in a standard solid-state oxygen system?

What are the comparative advantages of solid-state oxygen systems to liquid or gas?

A

120 CUBIC FT;
MOST EFFICIENT SPACE wise;
LESS EQUIPMENT and MAINATAINENCE;
Only requires INTEGRITY INSPECTION until ACTUAL USE is implemented

35
Q

What are the most common fire and smoke detection systems?

A

SPOT TYPE;

CONTINUOUS LOOP/LIVE WIRE (more common)

36
Q

What is the principle of operation of the continous loop detection system?
What is the advantage of it compared to spot type?
What are the types of continuous loop?

A

OVER-HEAT system that has HEAT SENSITIVE UNITS which COMPLETE ELECTRICAL CIRCUITS at a specific TEMP;
Permits more COMPLETE COVERAGE of FIRE hazard AREA;
KIDDLE and FENWAL

37
Q

What fire extinguishing systems are found in the cockpit and cargo area?
WHat si the principle of operation of the cargo extinguisher?

A

Cockpit: HANDHELD extinguisher;
Cargo: FIXED REMOTE controlled system with 2 steps;
INITIAL amount of AGENT sprayed, then sprayed SLOWLY to MAINTAIN amount of AGENT in compartment for 30 MINUTES or MORE depending on SIZE;
CONTAINER DISCHARGES into LINE which sprays AGENT into compartment when EXTINGUISHER SWITCH is ACTIVATED

38
Q

What fire protection is used in the toilets of aircraft?

A

A EUTECTIC HEAD/SQUIB which MELTS at 70-75C allowing extinguishing agent to exit bottle

39
Q

What are the main extinguishing agents in aircraft?

A

WATER: COOLS fire and EXCLUDES OXYGEN NO ELECTRICAL fires;
CO2: DISPLACES OXYGEN in atmosphere FOR ELECTRICAL fires;
DRY CHEMICAL: SMOTHERS fire which EXCLUDES OXYGEN NO COCKPIT fires;
HALOGENATED HYDROCARBONS: CHEMICALLY INTERFERES with COMBUSTION

40
Q

Where are smoke detectors usually positioned?

What are the classifications of smoke detector?

A

Where type of FIRE is anticipated to GENERATE SUBSTANTIAL SMOKE BEFORE TEMP CHANGES are sufficient to ACTUATE HEAT DETECTION system;
Type I: Measurement of CO (CO detector);
Type II: Measurement of LIGHT TRANSMISSIBILITY (PHOTOELECTRIC detector);
Type III: VISUAL DETECTION by viewing AIR SAMPLES (VISUAL devices)

41
Q

What is the operation of a single wire thermal switch?

A

28V DC is applied to BOTH parts of THERMAL LOOP;
If OVERHEAT occurs to the ALARM TEMP or FIRE occurs a SWITCH is CLOSED and GROUNDS the circuit completing it;
This causes INDICATION to be displayed in COCKPIT

42
Q

If a fire is detected at one point by a single wire thermal loop how will the rest of the system respond?

A

Still provides PROTECTION at other SURVEILLANCE points

43
Q

What does the test switch do in a single wire thermal loop?
What would a short in the circuit do?
Is the operation of the system different at night?

A

TESTS ENTIRE LOOP, will show if there is OPEN CIRCUIT in POWER INPUT LEAD of LOOP;
Causes a FALSE INDICATION;
DIMMING RELAY provides LOW VOLTAGE to the LIGHT

44
Q

What is the principle of operation of the continuous loop system ie: Kidde/Fenwal?
What is the difference between Kidde and Fenwal?

A

28V DC supplied to HOT LEAD through ALARM RELAY COIL;
When COOL, CURRENT does NOT FLOW between GROUND and LEAD;
When FIRE occurs, INSULATION MATERIAL HEATS and LOSES RESISTANCE sufficiently to COMPLETE PATH to GROUND;
RELAY COIL ENERGISES by current and ALARM LIGHT illuminates in COCKPIT;
Kidde: THERMISTOR INSULATOR 2 RODS;
Fenwal: EUTECTIC SALT 1 ROD

45
Q

What determines the effectiveness of a primary control?

A

AERODYNAMIC FORCE generated for a given DEFLECTION;

MOMENT ARM from CoG

46
Q

How does control effectiveness change with low and high speeds?
What effects can this have on the structure?

A

Low: Significantly LESS effective for a given DEFLECTION;
High: May be so GREAT that with necessary FLEXIBILITY of structure the RESULTANT FORCE may TWIST WING about TORSIONAL AXIS

47
Q

How is torsional twisting at high speeds minimised?

What is the operation of this system?

A

PRIMARY CONTROLS are SPLIT;
Operate in TANDEM at LOW SPEED;
Use LOCKOUT system at HIGH SPEED which is AUTOMATICALLY ACTUATED by signals from ADC ie: only INBOARD sections used or FLAPERONS/ELEVONS

48
Q

What is the problem with a power-boosted control system?

A

During TRANSONIC FLIGHT, SHOCKWAVES form on CONTROL SURFACE which results in BUFFETING feeding a FORCE to CONTROL system;
This FORCE does NOT reach the PILOT due to POWER operated IRREVERSIBLE control system

49
Q

How do the flight controls in the cockpit move the control surfaces?
How can the pilot experience a feeling of the control surfaces?

A

ACTUATES control VALVES LOCATED by COCKPIT controls that directs HYDRAULIC FLUID to control surface ACTUATORS or POWER CONTROL UNITS;
ARTIFICIAL FEEL/Q FEEL is built in to make STICK FORCE PROPORTIONAL to FLIGHT LOADS

50
Q

List what can be done when hydraulic power is lost in regards to power controls?

A

MANUAL DISCONNECT/REVERSION system;
ELECTRICAL backup system;
FUEL TRANSFER to ROLL and ENGINE POWER to TURN

51
Q

What do position transducers do?
What is the operation of position transducers?
What are the additional functions?

A

CONVERT CREW COMMAND INPUTS to analogue ELECTRICAL signals;
Signals are CONVERTED to DIGITAL form and sent to PRIMARY FLIGHT COMPUTERS;
Signals ANALYSED and if OUTSIDE ENVELOPE it can be MODIFIED;
Can be operated via IFS providing AUTO FLIGHT control and FEED FLIGHT control POSITION DATA to FDR

52
Q

What is the operation of engine nacelle fire extinguishing with 1 bottle?
Can it be controlled from cockpit?

A

BOTTLE is PRESSURISED to 500-600PSI;
RELIEF VALVE is FUSIBLE DISK which RUPTURES if bottle OVERHEATS;
To discharge from cockpit, ELECTRICAL CURRENT is applied to CONTACTOR which DENOTES EXPLOSIVE CARTRIDGE:
This SHATTERS DISK in bottle OUTLET and AGENT flows to ENGINE;
Can CROSSFEED if required

53
Q

What are the common extinguishing agents for gas turbine engines?

A 
CO2
METHYL BROMIDE (CH3Br2)
54
Q

What is the principle of operation of the CSD?

Draw a diagram?

A

Input from ENGINE turns GEARS;
FIXED DISPLACEMENT PUMP INCREASES/DECREASES PRESSURE changing OIL FLOW;
OIL flows to CONTROL CYLINDER which is connected to the VARIABLE DISPLACEMENT PUMP which adds/takes away BRAKING on the GEARS connected to the GENRATOR OUTPUT and OIL PUMP driving CHARGE OIL;
OIL also flows to GOVERNOR which acts to STABILISE PRESSURE;
DIFFERENTIAL UNIT included

Part 4 Systems (4 decks)

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