Brainscape's Knowledge GenomeTM

Browse over 1 million classes created by top students, professors, publishers, and experts.


See full index

Part 4 Systems Final Exam > Systems Final Exam > Flashcards

Systems Final Exam Flashcards

1
Q

what is the function of the electrical system on a large transport aircraft?

A

generate, regulate and distribute electrical power throughout the aircraft

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

how many electrical systems are there

A

there is usually more than one system and comprise of a mixture of AC and DC circuits

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

what is the normal config of a electrical system

A

will have a separate AC circuit powered by the alternator fitted to each engine and each circuit will feed a specific bus

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

why is AC more common in use than DC

A

AC alternators are more light than DC generators of similar capacity

diameter of AC wiring is smaller which makes it lighter

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

how is electricity supplied on an aircraft thru the battery

A

when connected to a complete electrical circuit, the battery converts chemical energy to electrical energy and a current will flow. the flow will stop if the circuit is switched off or the battery has exhausted it’s chemical energy.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

explain the basic bus system

A

power supply is routed to a common bar, off which several components or services can be powered.

this splits the electrical system into channels so that some parts can be prioritized in the event of a supply breakdown

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

what are the different types of bus system

A

parallel type
split bus type
split parallel type

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

how is DC power provided on an aircraft

A

AC power is rectified using a full wave rectifier
(AC can be produced from DC using a static INVERTER in an emergency also)

DC circuits have their own bus system isolating them from the AC bus

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

explain how the CSD works

A

the AC alternator requires power at a constant 400hz. the frequency is determined by the rotation speed of the armature, which is driven by the engine. The engine however doesn’t output a constant speed so a constant frequency can’t be delivered unless a device (CSD) is installed so that no matter what the speed of the engine is, the alternator can still output 400hz.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

what are the characteristics of AC generators

A

may be self excited, pilot excited or externally excited from the a/c DC bus bar

output is 400hz and power rating is 20-60 kilovolt amperes

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

what is the advantage of a 3 phase supply over a single phase supply

A

a 3 phase supply increases the amount of current available hence power to components.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

what are the implications of connecting 3 phase motors to components

A

connecting 3 phase equipment correctly is important because if not done properly it will cause eg. motor to rotate in opposite direction.

connecting 3 phase motors in parallel with incorrect phase could cause burn out

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

what purposes do air conditioning and pressurisation have on an aircraft

A
  • conditioned air for heating/cooling cabin/cockpit
  • prevent condensation on a/c equipment leading to avionics damage to protect avionics
  • provide conditioning for cargo as animals sometimes stored
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

what systems are the cabin air con and pressurisation systems broken down into

A
  • pressurisation system
  • air con system
  • heating system
  • oxygen system
  • pressure cell

supplied inhabited areas of a/c with temp control and safe atmospheric pressure lvl - ensuring safe oxygen lvl at altitude.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

what is PD

what is the standard PD

A

pressure differential, the difference between pressure inside the hull and the ambient pressure.

the system maintains a cabin alt of 8,000ft regardless of the altitude the aircraft is flying. if the a/c climbs beyond 8,000ft then PD will increase

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

how is PD controlled

A

controlling outflow of air from the fuselage. as air con flows in, the outflow is regulated at a lesser rate by a a rate controller. it also controls cabin VS.

when desired PD is achieved, outflow is increased again at a rate that will maintain the desired PD level

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

describe the cabin altitude profile as the a/c climbs

A

as it climbs:

  • ambient pressure decreases and cabin pressure decreases BUT at a lesser rate than the a/c itself.
  • cabin pressure change is controlled by cabin vertical speed in 1000’s fpm
  • outflow valve, controlled by crew setting controls cabin pressure and cabin vertical speed to maintain safe PSID.
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

what is the function of the air con system

A

maintain a comfortable air temp within aircraft fuselage

achieved through use of a heating system and auto control system where crew can select temp it’ll maintain.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
19
Q

what are the 3 key requirements of a air con system

A
  1. a pressure cell designed to withstand pressure differential
  2. the ability to respond to rapid changes in ambient temp and pressure
  3. an air supply capable of providing sufficient air for cabin pressurisation and air conditioning.
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
20
Q

how many cooling units are in the air con system

A
  • there are 3

- 2 of them are primary and secondary heat exchangers, the 3rd being the refrigeration unit.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
21
Q

what is the purpose of the primary heat exchanger

A
  • to cool the compressed air being bled directly from the engine compressor to a typical temp of approx. 300F.
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
22
Q

what is the purpose of the secondary heat exchanger

A
  • cooling the system air further so that the refrigeration unit can operate efficiently
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
23
Q

what is the purpose of the refrigeration unit

A
  • to provide the system with air at a temp appropriate for the provision of the necessary cabin comfort expected of air con systems.
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
24
Q

what are the safety features of the environmental system

A
  • pressure control valve
  • pressure relief valve (used to ensure pressure does not build up beyond max operating pressure)
  • negative pressure valve ( ensures pressure outside cabin never exceeds pressure inside the cabin and operates automatically
  • emergency depressurisation valve (activated by WOW switch)
  • emergency cabin altitude control
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
25
Q

how is the environmental system controlled from the cockpit

A

simple systems have a OFF-NORMAL-RAM setting

most modern aircraft have a panel where individual temps can be set in the cabin and cockpit.
- also will have individual pressure controls on the panel incl. emergency controls and warning lights

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
26
Q

what other controls are on the cabin environment panel in the cockpit

A
  • cabin pressure controller
  • rate selector
  • landing altitude selector
  • barometric pressure selector
  • emergency controls and warning lights

works in conjunction with central warning system

if APU has ability to operate system it will be available on panel

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
27
Q

how is air distributed in the environmental system, is there more than one method?

A
  • via ducts and diffusers
  • some a/c may have duplicate systems feeding from each engine and feed to different areas of the a/c. (this has redundancy so if one fails the other will still work).
28
Q

when might 1 environmental system have to be shut down

A

high power operating conditions eg

  • high altitude runway ops
  • heavy icing conditions
  • fully laden a/c.
29
Q

how much of the air in the environmental system is recycled

what’s used if both engine driven systems fail?

A

50% is recycled to reduce load on air delivery system

most systems will have an alternate ram air provision which allows for fresh air to be provided should both engine driven systems fail

30
Q

What elements make up the temp control system

A

consists of:

  • cabin temp controller
  • temp selector knob
  • two position temp control switch
  • modulating bypass valve
  • control network
31
Q

How does the temp control system operate and what modes does it operate under

A
  • when temp control switch is in AUTO, bypass valve will seek a valve gate position resulting in the duct temp corresponding to temp controller setting.
  • accomplished though the control network which transmits signals from sensing element to cabin temp controller, which electrically positions valve in relation to settings of the temp control knob
  • when temp control switch is in MAN, controller will control bypass valve directly without reference to duct temp. desired temps are maintained monitoring the air temp knob.
32
Q

how does the primary heat exchanger work

A
  • the unit reduces the temp of the engine bleed air by routing it through the veins in the core of the heat exchanger.
  • during flight the core is cooled by ram air and the amount of air to be cooled is controlled by the primary heat exchanger bypass valve.
33
Q

explain how vapor cycle air conditioning works

A

on the principle of latent heat

the refrigerant changes state from liquid to vapor, and in doing so absorbs heat from the cabin. this heat is sent outside the aircraft as the refrigerant returns to a liquid state.

34
Q

what material is used as a refrigerant for commercial a/c

A

dichlorodifluoromethane AKA

  • Refrigerant 12 OR
  • R-12
35
Q

what are the characteristics of dichlorodifluoromethane

A
  • stable compound at high and low temps
  • doesn’t react with any materials in the system
  • doesn’t attack rubber sealings
  • colorless and odorless
36
Q

what else is termed as dichlorodifluoromethane

A
  • Refrigerant 12
  • R-12
  • Freon 12
  • Genetron 12
  • Isotron 12
  • Ucon 12
  • Freon 22 is similar to Freon 12 but NOT the same thing as it has different vapor pressure.
37
Q

what is the requirement for oxygen supply on large transport aircraft

A

enough for the aircraft to descend from cruising altitude to 14,000ft in less than 4 minutes without exhausting the oxygen supply

38
Q

what are the advantages and disadvantages of chemical oxygen systems

A

advantages:
- lightweight
- less equipment
- less maintenance

disadvantages:

  • fire hazard higher
  • not tamperproof
  • won’t turn off
39
Q

How is the continuous flow oxygen system arranged in the passenger environment

A
  • may consist of a series of plug in supply sockets fitted to the cabin walls adjacent to pax seats to which oxygen masks can be connected
  • can be a drop out arrangement where masks are presented automatically is pressurization fails.
  • in both cases oxygen is supplied from a manifold and any automatic control can be over ridden by a crew member.
40
Q

Why are solid state oxygen generators the most efficient option

A
  • the oxygen occupies much less volume as a gas so it is more efficient in space.
  • less equipment and maintenance is required for solid state oxygen converters.
41
Q

what fire and smoke detection systems are common in use

A
  • spot type system

- continuous loop detector system (AKA live wire detection system - the most common one)

42
Q

What are the characteristics of the continuous loop detector system

A
  • permits more complete coverage of a fire hazard area than spot type.
  • they are overheat, heat sensitive units that complete electrical circuits at a certain temp, activating the warning system
43
Q

what are the 2 main types of continuous loop fire detection systems

A
  • Kidde system

- Fenwal system

44
Q

how does the smoke detector work in the engine nacelle

A

uses photoelectric cells with a light beam directed toward them. if enough smoke is present, the light beam refracts light to the cells causing the alarm to sound.

45
Q

how does fire extinguishing work inside the engine nacelle

A
  • bottle is powered at 500-600psi.
  • has a relief valve that will rupture if the bottle were to overheat
  • the bottle is discharged from the cockpit by an electrical current applied to contactor which detonates an explosive cartridge and shatters a disk at the bottle outlet letting the agent flow
46
Q

how does an x feed extinguishing system work

A
  • allows a eg. number one engine fire to be taken out with either the number 1 or number 2 bottle using x feeding
47
Q

how does the cabin and cargo area fire extinguishing system work

A
  • has a fixed remote controlled system designed to extinguish fires in 2 steps:
    1. - an initial amount of agent is sprayed into the compartment
    2. - more agent is then slowly added in order to maintain the amount of agent in the compartment for 30 minutes or more depending on compartment size.
48
Q

where does the cabin and cargo fire extinguishing container discharge

A

it discharges into a line which sprays the agent out into the compartment when the extinguisher switch is activated

49
Q

what are the 4 types of extinguishing agents

A
  1. Water (cools fire and excludes oxygen)
  2. carbon dioxide (displaces surrounding oxygen)
  3. dry chemical (smothers the fire excluding oxygen)
  4. halogenated hydrocarbons (chemically interferes with combustion)
50
Q

what are the characteristics of automatically fired extinguishing systems? where are they found?

A

usually found in toilets

  • the fire bottle is fitted with a squib which melts at 70-75 degrees, allowing the extinguishing agent to exit the bottle
51
Q

what are the different classifications of smoke detection instruments

A

Type 1 - measurement of carbon monoxide gas (CO detectors)

Type 2 - measurement of light transmissibility in air (photoelectric devices)

Type 3 - visual detection of the presence of smoke by directly viewing air samples (visual devices)

52
Q

How can smoke detectors always remain reliable

A

they must be maintained so that smoke in a compartment will be indicated as soon as it starts to accumulate.

Smoke detector louvers, vents and ducts must not be obstructed.

53
Q

how does the single wire thermal switch work

A
  • 28V DC is applied to both paths of thermal switch loop
  • if heating to alarm temp occurs which closes any switches, a ground is formed through closed switch.
  • with that arrangement, one open circuit can occur and system will provide protection at all surveillance points.

REFER DIAGRAM

54
Q

what are the test and circuit short functions in the single wire thermal switch

A

test switch tests entire loop and shows if an open circuit is present

a short circuit will cause false warning indications

dimming relay dims the light at night for night ops.

55
Q

how does the continuous loop detection system work

A
  • 28V DC applied to hot lead thru alarm relay coil.
  • when heated, insulator material loses resistance and forms a path to ground
  • relay coil is energized by the current flow and alarm light is illuminated

REFER DIAGRAM

56
Q

how are buffeting forces dampened

A

power operated irreversible control system

cockpit controls actuate control valves which direct hydraulic fluid to control surface actuators (PCU)

  • artificial load is built into the system so pilot has more control feel
57
Q

what is the problem of the power boosted control system

A

during transonic flight, shock waves form on control surfaces causing buffeting

58
Q

how does the fly by wire system work

A

crew command inputs are translated into electrical signals

signals go to actuator control electronics

signals converted to digital format and sent to primary flight computer

inputs are analyzed, and if outside flight control envelope the signals are modified so they stay inside

can be operated with IFS providing auto flight control and feed flight control data to the FDC

59
Q

What do aircraft have for then there’s hydraulic power loss

A
  • they have a manual disconnect or manual reversion system which allows crew to fly the aircraft manually (more recent backup systems are electrically powered)
  • fuel transfer can be used to roll the a/c and engine power imbalance to turn in extreme cases
60
Q

what does the effectiveness of a primary flight control depend on

A
  • aerodynamic force generated by control deflection

- moment arm from CoG

61
Q

what does aerodynamic force depend on

A
  • amount of deflection

- dynamic pressure exerted by airflow

62
Q

what can happen to the wing at high speed

A
  • control effectiveness be so great that resultant force may twist wing about it’s torsional axis
  • split flight controls minimise this happening
63
Q

how do split flight controls work

A
  • operated in tandem at low speeds and lockout system used to utilize to provide split operation at high speeds
  • lockout system works on data fed from ADC so inboard ailerons are only used over a specified speed or flaperons/elevons may be employed.
64
Q

How does the Fenwal continuous loop detection system work

A

an Inconel tube fitted with thermally sensitive salt and a center conductor

they are fitted to a control unit which impresses a small voltage on the sensing elements

when overheat occurs the resisitance of the salt drops causing current to flow to the control unit and sounding the alarm

when temp drops back down the resisitance increases again and it goes back on standby

65
Q

how does the kidde continuous loop detection system work

A

2 conductors go thru tube with one going to ground and the other to the fire detection control unit

as temp increases resistance to ground decreases and fire detection control unit monitors this change

there is an overheat point and a fire point (overheat will have 10 sec delay)

rate of change of resistance indicates a short or fire, if to goes down real quick then its probably a short

Part 4 Systems Final Exam (2 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2024 Bold Learning Solutions. Terms and Conditions