1
Q
What does redundancy involve?
A
Duplicating critical parts of the structure so that if one fails, the other can still carry the loads.
2
Q
When are stress and strain present in the airframe?
A
Always, even when stationary on the ground.
3
Q
What 5 types of loads do aircraft experience and when? What relieves bending loads?
A
Static loads
Horizontal loads
Dynamic loads (in flight)
Cyclic loads (each flight)
Vertical loads (caused by lift and weight)
Wing fuel relieves bending loads
4
Q
What are the areas most prone to stress? (X2) What 4 things must be checked for pre-flight? CPBS
A
Wings and wing roots
Cracks, popped rivets, buckled skin, signs of structural distortion.
5
Q
What effect can corrosion have on a structure? What can this provide? What 3 things should be watched for?
A
Can weaken a structure and provide a locus for fatigue cracks to start.
Watch for rust, discolouration, signs of pitting on metal components.
6
Q
What 2 atmospheric properties promote corrosion? What 2 things can help prevent this and why?
A
Salt-laden atmospheres and warm humid environments.
Wash often to remove salt
Oil applied to bare metal
7
Q
What 4 factors / practices increase risk of metal fatigue?
A
Corrosion
High number of flight cycles
Hard manoeuvring (but not just once..)
Poor maintenance practices
8
Q
When does hard-time maintenance occur? When does on condition maintenance occur and what is it (2 options)?
A
Fixed intervals
Replacement or refurbishment if necessary following inspection
9
Q
What 3 materials can composites comprise? What 2 things are these materials bonded to if used in composites?
A
Carbon, glass, Kevlar (aramid).
Bonded with resin and filler.
10
Q
Where are different types of composites used?
A
In different areas of the aircraft depending on the task they have to satisfy.
11
Q
What are 3 properties of composites? What are they resistant to (x2)?
A
Light, stiff, strong
Resistant to fatigue and corrosion
12
Q
Through which 2 ways can composites be tailored? (SS) What’s a downside of composites?
A
Shaped
Stiffness (directionally tailored)
Expensive
13
Q
Why are carbon-based composites useful in lightning storms?
A
Conduct electricity well, giving some protection from lightning strikes.
14
Q
What 3 indications may suggest damage to composites?
A
Delamination, distortion, protruding fibres
Damage may be difficult to spot
15
Q
Why are mass limits imposed on the structure? Give 4 limiting structural masses.
A
Strength is finite
Maximum structural ramp mass: maximum permissible mass before aircraft starts to taxi
Maximum structural takeoff mass: maximum permissible mass at the start of the takeoff run
Maximum zero fuel mass: maximum mass when aircraft is unfuelled
Maximum structural landing mass: maximum permissible mass on landing, in normal circumstances.
16
Q
What 4 aircraft designs are there?
A
High wing
Low wing
High or mid-set tail plane and t-tail
17
Q
What 2 types of fuselage construction are there? (Remember f+r)
A
Monocoque (structural shell)
Semi-monocoque (a shell over frames and ribs)
18
Q
6 methods of fixing components of aircraft structure?
SAP BWR
A
Riveting
Welding
Bolting
Pinning
Adhesives (bonding)
Screwing (fastening)
19
Q
What do frames define?
What 3 things provide a base for the skin? (SSL)
What do cross-beams support?
A
Shape
Stiffeners, stringers, longerons
Floor panels
20
Q
What are doublers?
A
A second overlapping layer of material that may be used at joints
21
Q
Where are pressurised bulkheads situated?
A
At each end of the fuselage
22
Q
What are situated between pressurised bulkheads?
A
Other structural and non-structural bulkheads
23
Q
What are 4 examples of fuselage shapes?
A
Circular (easy to make)
Oval (efficient for two decks)
Double-bubble (specialist applications)
Rectangular (maximise cargo volume)
24
Q
What is the pressure hull and what 2 stresses does it experience? (H+A)
A
Everything between the pressure bulkheads
Hoop and axial stress
25
What can a tail strike cause?
Critical, potentially catastrophic (but unseen) damage to the rear pressure bulkhead.
26
What is the key structural component of the wing?
Main spar(s)
27
What 3 things is wing shape achieved with? What do most wings house?
Shaped skin mounted on ribs, and longerons.
Fuel tanks
28
What do large aircraft wings use for the main spar? What is this attached to?
Torsion box
Centre wing box
29
What 2 properties are wings built with (compromise reached between the two)?
Good torsional stiffness but with enough bending flexibility to absorb vertical loads without failing
30
What is flutter? Why (x2)?
An oscillation caused by the interplay between aerodynamic forces and torsional stiffness.
31
What is torsional stiffness?
The tendency of the structure to return to its original shape
32
In which 3 major components can flutter occur in?
Wings and horizontal stabilisers and tailplane
33
3 flutter countermeasures? (Inc. 1 structural)
Forward-mounted engines on wing
Forward CG bias to integral wing tanks
Good torsional stiffness
34
What type of forces are imposed in asymmetrical flight? What is one way the fin can become overstressed?
Lateral
Unnecessarily large rudder inputs
35
How do doors hinge? How do hatches hinge? On what side are pax. loading doors on CAT aircraft?
On vertical edges
On horizontal (top) edges
Port side (left)
36
How are plug doors secured? Do Unpressurised aircraft have plug type doors? How does the number of hinges compare?
Multiple bolts around periphery
No; fewer hinges
37
How are flight deck windows strengthened? What gives them enough flexibility to withstand bird strikes? What does this also allow?
With multiple layers
Being heated (also helps anti-icing)
38
What is a CS-25 requirement relating to direct vision windows?
They must be able to be opened in flight (when aircraft is Unpressurised)
39
What is an eye reference position?
A REQUIREMENT to ensure that each pilot sits at the design eye point.
40
Which 2 systems ensure equal pressure between cabin and cargo compartments? What does this prevent?
Floor vents and/or blow-out panels
Prevents floor buckling if cargo door fails
41
Which fluids have pressure and when? What kind of pressure does air have? What kind of pressure do liquids have?
All fluids, even when at rest
Air pressure
Hydrostatic pressure
42
What is hydrostatic pressure caused by?
Weight force of fluid acting on itself
43
In which directions does hydrostatic pressure act in at what time?
All directions simultaneously
44
What is Pascal’s law?
Pressure exerted anywhere in a confined, incompressible fluid is transmitted equally in all directions throughout the fluid.
45
Pressure units for hydraulics?
Lb / inch squared
46
If a piston in a cylinder is connected to another cylinder which has a piston, how is the pressure translated between them?
Pressure on one piston is immediately translated into a force on the other
47
How does a piston in a larger cylinder manipulate “P=F/A”? What comparative distance does this act over?
Piston in larger second cylinder has more area over which F acts, so:
Much greater pressure is extorted by second piston
However, over smaller distance
48
What happens to force when small pistons operate much larger ones?
Multiplied
49
6 properties of an ideal hydraulic fluid?
TH LLL R
Thermal stability
High flashpoint
Low flammability
Low volatility
Low viscosity
Resists corrosion
50
Why should one be cautious around hydraulic fluids? (X2)
Corrosive and irritate eyes and skin
51
What are 2 types of fluid? Can one mix them?
Synthetic and mineral
NO
52
What is 1 property of hydraulic fluid used in aircraft systems? What pressure range is used in aircraft systems?
Incompressible
2000-5000 psi
53
3 benefits of hydraulic systems over mechanical?
Ability to deliver very large amounts of force with little effort
Light
Very little energy lost transmitting power
54
6 components of hydraulic systems? PSH RNF
Piston in cylinder (actuator) to operate a component
Source of power (pump) to generate pressure and selector valve to direct pressure to either side of actuator
Hydraulic lines to deliver fluid to and from actuator
Reservoir to feed and replenish system
Non-return valves to prevent back flow
Filters to clean the fluid
55
6 uses of hydraulic systems? (BCR) (hatch)
Flight controls (flaps, spoilers, speed brake)
Landing gear
Nose wheel steering
Wheel brakes
Cargo hatches
Thrust reversers
56
Two types of hydraulic systems? What does each one use?
Active: pressure pump
Passive: human effort (eg. pressing on a brake pedal to apply force to brake callipers)
57
Typical psi of low pressure systems? What about high pressure systems?
Up to 2000 psi
Typically 3000 psi (some aircraft 4-5000 psi)
58
Mass of high pressure vs low pressure hydraulic systems?
High pressure lighter
59
With no external forces applied other than gravity, a reservoir of fluid possesses _____ static pressure throughout its volume?
Variable
60
What does a single-acting actuator do?
Uses hydraulic pressure to move a piston in one direction only
61
What does a double-acting actuator do?
Directs hydraulic pressure to either side of the piston to move it in two directions.
62
What do non-return (check) valves allow?
Pressure to be maintained in local parts of the system by allowing fluid to move in one direction only.
63
What 3 types of selector valves are there? What 2 things can operate them? Which 2 places do selector valves direct fluid pressure?
Two-port, four-port, linear
Operated by pilot or other systems
Direct fluid pressure to various parts of the system or to either side of an actuator
64
Through which 2 ways may pumps work? Give 2 practical examples. (In terms of frequency of supply)
Active on demand or constantly supply pressure to the system.
Eg. Electrically driven pump in a light aircraft to operate the landing gear.
Eg. Engine driven pump in large aircraft constantly supplying pressure to a system (eg. Flight controls).
65
Two types of pump? (…pressure …gear)
Constant pressure; spur gear
66
2 examples of constant pressure pump? What are they operated by? (___ plate)
Swash-plate or cam-plate, operated by a control piston
67
What does outlet pressure depend on in a spur gear?
RPM
68
Through which 5 ways can pumps be driven in an aircraft?
Electrically, by a RAT, by an engine, by hand, by hydraulic motor.
69
What does the reservoir have (to provide an emergency supply), store, allow, and accept (via what?)?
Stores excess fluid
Allows thermal expansion
Accepts fluid returning via drain lines
Has a stack pipe to provide an emergency supply
70
What is the role of the baffle in reservoirs? How do they prevent boiling at altitude?
To de-aerate the returning fluid and are normally pressurised to prevents boiling at altitude.
71
What do accumulators store and how? What are they used for (x2)?
Pressure using compressed nitrogen. Used to even out pressure spikes (hammering) and supply emergency pressure if a pump fails.
72
How do filters deal with blockages?
Bypass system
73
What is the role of relief valves in hydraulic systems? What about restrictor valves, priority valves, shuttle valves, fuses, fire shut-off valves?
Vent excess pressure
Reduce flow speed, maintain pressure in one part of the system, automatically supply a service from highest power source, automatically shut off a leaking part of a system, shut off a system or part of a system in the event of a fire.
74
Hydraulic systems are at least _________ on commercial aircraft. ________ in all other respects. A _____ may be used so that one can power the other.
Duplicated
Separate
PTU
75
What does the fuel control panel allow (x1) and what indications do they provide (x3)?
Pumps to be switched on
Low pressure and high temps and fluid quantity
76
What may high temperature or low pressure indicate? (Potentially caused by…)
Leak in the system
77
What is high system demand and what may this cause? What may this result in? (Hydraulic systems)
Lots of services operated simultaneously may cause temporary low pressure resulting in slower activation of the services.
78
Are reservoirs pressurised?
Sometimes
79
4 main types of gear? What do high speed aircraft always have?
Tricycle, with nose wheel
Tail wheel
Retractable or fixed
Always retractable for high speed aircraft
80
What do oleos do and how? Within what does the piston move in, and what 2 substances help to absorb and even-out shocks?
Absorb shock of landing by compressing.
Piston moves inside a cylinder.
Nitrogen and restricted oil flow help to absorb and even-out shocks.
81
What must be checked in relation to oleos before flight? What is a problem that may be found here, and what might be the cause?
Correct extension
Too compressed probably means insufficient oil or low nitrogen pressure.
82
What do bogies contain, and on what? What is each pair of wheels mounted on?
Multiple wheels on a bogie beam. Each pair of wheels are mounted on an axle attached to the bogie beam.
83
How many wheels do nose wheel assemblies have? On what are they mounted?
1 or 2, mounted on an axle.
84
What do drags struts do? What about side-strays? What about torque links (x2)?
Brace the gear against fore/aft shock loads.
Side strays brace the gear against side loads.
Torque links align the gear and retain oleo position in its cylinder when strut is extended.
85
3 steps in i. Gear extension, ii. Gear retraction.
Extension: all doors open, gear extends, some doors retract.
Retraction: some doors open, gear retracts, all doors close.
86
What is gear held up by? (X1) What is gear held down by? (X2)
Hydraulic up locks.
Hydraulic down-locks and over-centre locks.
87
By whom is normal operation of the landing gear controlled by? How? What 2 (sometimes 3) modes does this have?
Pilot, using landing gear lever.
UP, DOWN, sometime OFF/centred position.
88
What do red/green lights signal on the landing gear panel?
Green: down AND locked
Red: unlocked or travelling
89
How is inadvertent gear raising on the ground prevented? (What switch activates the appropriate system?)
Weight-on-wheels switch activates an interlock in the landing gear
90
Through which 2 methods may gear be manually extended by? What must be done before operating these?
Manual hand pump, or gravity/nitrogen blow down.
Select down on normal system first before operating the emergency system.
91
Is it possible to retract gear once emergency system has been used? What 2 things must be used after use?
No
Ground locking pins
Ground locks
92
2 methods of steering?
Differential main wheel braking and a castoring nose wheel
Steerable nose wheel linked to rudder pedals or tiller
93
What may be used for powering nose wheel steering?
Hydraulic or electric motor.
94
What may very large aircraft use on the rear bogies when on the ground?
Main wheel steering to relieve stress on main tyres when turning and to reduce turning radius.
95
What are VLO and VLE and what are they subject to?
VLO: gear operation speed
VLE: gear extension speed
96
When does a nose wheel centring system operate and why?
On retraction to avoid a spinning tyre wearing against the wheel bay walls.
97
What is used to prevent gear collapsing on the ground? What’s important to remember with these?
Aircraft locking pins are inserted when the aircraft has parked. They must be removed before flight.
98
What does shimmy occur to? What is it and which 2 things reduce it? (Type of damper and type of tyre)
Nose wheels
Violent oscillation left and right causing shuddering and vibration
Prevented/reduced by shimmy dampers or mastrand tyres.
99
Why is a nose wheel first landing so dangerous? What will likely happen to the struts and mounts? What might happen to a nose landing on a long aircraft?
Strut and mounts are not built to withstand the shock of landing.
They will probably collapse or be severely damaged.
Heavy nose wheel landing on an aircraft with a long fuselage will bend and damage the fuselage structure.
100
Two types of tyre? Two types of tyre carcasses?
Tubed or tubeless
Radial or cross-ply built
101
What is ply rating an indication of? What does tread do and how, and what type of tread is usually found on tyres? What is re-tread?
Tyre strength
Adds grip by expelling water, ribbed
Bonding a new tread pattern on a worn tyre
102
What is creep? What is it caused by, how is it monitored, what must be done with excessive creep?
Movement of tyre around rim
Rapid acceleration on landing
Creep marks
Must be corrected
103
Why are tyres subject to a tyre limiting speed? (What type of force is limiting?)
Their structure is only able to withstand a limited amount of ground-rolling forces.
104
What do cuts and excessive wear increase the risk of? What must be checked and what must never be accepted?
Tyre burst
Tread wear indicators in limits
Never accept tyre with significant cuts
105
What do thermal (fusible) plugs do? What is this typically the result of? (System of tyres)
Pop to release tyre pressure if it becomes excessive.
Usually result of overheat caused by excessive braking.
106
8 no-go items for tyres? SCEEB FFO
Significant cuts
Bulges
Flat spots
FOD
Contamination
Excessive creep
Excessive wear
Over/underinflated
107
What type of calliper is present in a disc brake? What is the calliper lined with? What does it clamp onto? What force slows the wheel?
Hydraulically-operated, lined with brake pads, clamps onto a disc bolted to the wheel, friction.
108
How many discs per wheel on light aircraft? What are they made from? What is the calliper operated by, and by how many?
1, made from steel. Calliper operated by 2 or 3 hydraulic pistons.
109
How many (general) discs are used on large aircraft braking systems? Between what are they sandwiched and how many, and what are these lined with? How is the assembly clamped together, and what is this to create?
Multiple discs are sandwiched between circular pressure plates lined with brake pads. Multiple pistons clamp the assembly together to create braking force.
110
How are the pistons in braking systems usually operated? On what new aircraft is this different? What does it use instead and why?
Hydraulically
787, electrically-operated to save weight.
111
What 2 materials are large aircraft brake discs typically made from? Which is superior and why (4 reasons)?
Steel and carbon
Carbon superior due to lighter, higher operating temperature limit, better coefficient of friction, and wears less.
112
Why do disc brakes heat up? What is the ability of a braking system therefore limited by?
Kinetic energy of aircraft is absorbed and translated into heat.
Ability of braking system limited by capacity to absorb heat.
113
What is brake fade? What is taxi and takeoff subject to? What do large aircraft have?
Where excessively hot brakes lose their ability to generate friction, leading to loss of braking.
Taxi and takeoff subject to maximum brake temperature limits.
Large aircraft have brake temperature displays.
114
What happens to brake pads with use? How is degree of wear indicated? When should these be checked?
Wear out
Brake wear indicator pins, checked before flight.
115
What provides emergency brake pressure in the event of pump failure on hydraulic braking systems?
Accumulator - enough pressure for six applications
116
How does anti-skid work? (X4)
Sensors measure wheel rotation
Computer detects rapid deceleration or one or more wheels
If detected, system releases brake pressure at affected wheel to allow it to spin back up
Brake pressure then automatically reapplied.
117
At what frequency can anti-skid operate at? What effect does it have on landing roll?
Many times per second
Substantially reduces landing roll in poor surface friction conditions (can halve landing roll)
118
What are touchdown and hydroplane protection?
Touchdown: releases pressure to brakes before landing
Hydroplane: applies pressure to rear wheels on a bogie
119
When is auto brake armed and what is it set to? What does it do after landing, and what other system does it require to be used?
Armed before landing and set to one of several levels
Automatically applies brakes after touchdown and decelerates aircraft gently or rapidly depending on braking level set
Requires operational anti-skid
120
When is auto brake automatically deactivated?
If pilot applies brakes manually
121
What level of braking does auto brake apply during RTO?
Max.
122
What are the 3 primary flight controls?
Elevators: adjust pitch
Ailerons: adjust roll
Rudder: adjust yaw
123
4 means of flight control actuation?
Manual: cables, pulleys, bell-cranks
Partially powered: cables and levers with actuator assistance
Electrically-powered: powering hydraulic actuators with electricity
Fully powered: no mechanical connection between pilot’s controls and control surfaces. Hydraulic actuators controlled by signals
124
What does “reversible controls” mean?
If you wiggle a control surface, the pilot’s controls move.
125
What are pilot’s controls connected to with manual controls? What happens when the pilot’s control is moved (what systems do they link to)? What is felt by the pilot through the controls and why?
Cables
Cable moves, acts on bell-cranks at control surface, causing it to move
Forces on control surfaces are felt by pilot - reversible control
126
When pilot’s controls are moved in partially-powered system, what 2 things move, and what does this cause? What is the relationship between hydraulic actuators and mechanical linkages here (how are they attached)? Are partially-powered systems reversible controls or not?
Control surface and servo, simultaneously.
This moves actuator.
Hydraulics actuators and mechanical linkages attached in parallel.
Reversible.
127
What is operated by pilot’s controls in full powered systems? What does this control, and what does THIS then move? What 2 methods are used to do this? Are these irreversible or reversible? How is artificial feel provided?
Servo valve, controlling an actuator (which moves control surface), is operated by controls. Mechanical or electrical methods used to do this.
Irreversible, artificial feel provided by springs.
128
For what reason is control “feel” required? What may happen without it?
To warn the pilot against overstressing the aircraft.
Without feel, excessively large control inputs at high airspeed would be too easy.
129
How does fly-by-wire compare to full-powered controls (they’re a version of them…)? By what are pilot’s inputs mediated by, and what do these provide (and how)?
2 benefits of FBW?
Electrical version of full-powered controls.
Computers, which provide envelope protections by preventing or modifying harsh/rash inputs.
Saves weight, reduces workload.
130
3 fly-by-wire modes of operation?
Normal
Degraded
Direct
131
What does normal mode mean in fly-by-wire systems? Give an example and benefit.
Fully operational
Eg. Airbus normal law
Low pilot workload
132
What is absent in degraded operation of fly-by-wire (x2)? Give an example of degraded mode?
Some protections and finessing
Airbus alternate law
133
What 2 things happen in direct law in fly-by-wire systems? (One involves computer mediation; the other is about the relationship between pilot input and control surface movement)
Effect on pilot?
All computer mediation absent
Simple relationship between pilot input and control surface movement
High workload
134
A disadvantage of fly-by-wire? (Think failure)
When sensors fail, mode protections can be wrongly triggered and interfere with valid pilot inputs.
135
What do sidestick controllers make it difficult to see? What happens to simultaneous inputs? What system helps this overall problem?
Difficult for one pilot to see and understand what the other is doing.
Simultaneous inputs are averaged.
Sidestick priority system helps
136
What do FBW systems have to move the controls? What do they have to interpret and moderate pilot demands? What do they have to provide feedback to computers? What do they have for redundancy?
Actuators
Computers
Control surface position senses
Triplicated or quadruplicated control wires running through different parts of the airframe.
137
What do primary controls have to null loads felt by pilot? What elements create balancing loads at the control surface? What method of control is this not applicable to?
Trimming function
Trim tabs
Sidestick
138
What is important to remember about trimming the horizontal stabiliser? (X2)
Extremely powerful
Trim device must be carefully managed and set precisely as calculated for takeoff
139
What do control locks protect against? What essential to check before flight?
Banging against control stops in gusty conditions when on the ground (reversible controls)
Check removed before flight
140
What is the role of the rudder limiter?
Limits rudder travel at high speed to prevent excessive loads on the fin.
141
Definition of secondary flight control?
One which does not directly alter yaw, pitch, roll
142
5 examples of secondary flight controls?
Trailing edge flap
Leading edge devices
Trimmers
Spoilers and speedbresks
143
By what are secondary flight controls often operated by and why?
Screwjacks or similar, because they’re not moving continuously.
144
How are secondary flight controls held at the required position? (Very simple; think “locked”).
Locking mechanisms
145
3 methods of actuation of secondary flight controls?
Electric/hydraulic motors or manually in light aircraft
146
What happens if flaps become asymmetrical? (How does the system stop this?)
Sensors monitor extension and stop flap travelling
147
What is a common property of slat extension and retraction?
Automatic
148
What are individual flap settings subject to? Why?
Speed limits
Delicate
149
What devices prevent flaps extending if speed is too high?
Load limit devices
150
4 examples of leading edge devices?
Droop nose
Krueger flaps
Leading edge flaps
Slats
151
Where are spoilers/lift dumpers? How do they extend i. in the air, and ii. on the ground, and why?
Upper surface of wing
Extend to disrupt lift on the ground
Extend slightly to increase drag in the air
152
What kind of instruments are pneumatics required for primarily, in light aircraft?
What two methods can light aircraft use for pneumatic systems?
Electro-mechanical instruments
Electrically driven compressors / vacuum pumps
153
What do large commercial aircraft use for heating, conditioning, de-ice / anti-ice, actuation of valves and pumps, engine starting, pressurisation of reservoirs? (X2 options)
Bleed air / electrically powered compressors
154
What 4 components comprise pneumatic systems? DIP T (2 types of valve)
Ducts, isolation valve, pressure reducing valve, temperature and pressure sensors.
155
What 2 components does engine bleed supply have? (Bleed air is hot…)
Pre-cooler
Engine bleed valves
156
What temperature is bleed air? Why is this dangerous?
400°C
Fracture of duct can cause hot gas leaks, resulting in serious systems and structural damage
157
What does control panel of pneumatic system give crew control of? (X2) (Think 737 OH)
Selector and isolator valves
158
For which 4 things may warnings be given for in the pneumatic system?
Over-temperature, over-pressure, low pressure, overheat/duct leak.
159
In what configuration must bleeds be in for engine start?
How might high power affect the availability of bleed air?
How can the system be monitored?
Off
Limited
Electronic system diagrams on EFIS system
160
How is warm air provided in a light aircraft? What do light aircraft have for cold air? (French)
Intake air is passed over a heat exchanger.
Louvres (outlet nozzle)
161
What 3 things do large aircraft’s air conditioning and pressurisation systems provide?
Ventilation, temperature control, cabin pressurisation.
162
What 2 things (one is a component) does the pressurisation system comprise? What is the component controlled via, and by what? (… controller)
Air from the conditioning packs
Outflow valve controlled via an actuator, by a pressure controller.
163
Where is the outflow valve located? What effect does opening it have on cabin pressure?
Aft fuselage
Decrease
164
What two differential pressure relief valves are present to guard against excessive forces on the fuselage structure? (1 for too much; 1 for too little)
Excessive differential pressure-relief valve
Negative differential pressure-relief valve
165
How is cabin pressure indicated? What is the maximum?
What is rate of change of cabin pressure indicated as?
Cabin altitude (8000 ft max.)
Cabin vertical speed
166
What is maximum aircraft altitude dictated by from a pressurisation point of view? What is this value?
Maximum differential pressure between cabin and ambient (8/9 psi).
167
What 2 things occur id cabin altitude exceeds 10,000ft?
What is the role of ground pressurisation?
Audio and visual warnings sound
To help even-out pressure fluctuations during takeoff.
168
What level of automation is pressurisation control? What must the crew do?
Semi-automatic
Switch on pressurisation.
169
What is the role of the pressurisation controller (how is it linked to actuation on outflow valve)? What is a property of the outflow valve that is useful in the event of controller failure?
To sense cabin altitude and adjust the position of the outflow valve to dump excess pressure or to raise it.
Outflow valve can be manually driven towards open or close.
170
With what is cabin conditioning achieved with? How many of these are there? Which 2 methods can be used to drive these components?
An air conditioning pack. At least 2. Electrical compressors or (more usually) engine bleed air.
171
Explain how bleed air comes from the engine, resulting in comfortable temperature air entering the cabin. (5 key points)
1. Cooled + valve
2. Heat ex.
3. Compression + …
4. Cools (unwanted)
5. Comfort
1. Bleed air is pre-cooled and passes through isolation valve.
2. Ram air duct passes cold air over a heat exchanger which also cools bleed air.
3. Air is compressed and then passed over a turbine.
4. In driving the turbine (which powers compressor) air loses most of its energy so cools to about 0°C.
5. Temperature controller mixes hot bleed air to cold air to ensure comfortable temperature air delivered to cabin.
172
Role of water separator? What does air pass through before entering cabin?
Extracts water from air to reduce humidity.
HEPA filter.
173
Role of trim air? What percentage of air is recycled and how? What happens to the rest?
Fine tune temperature in different parts of cabin.
50%, by recirculation fans.
50% exits via outflow valve.
174
What is the entire air conditioning pack cooled by? On a no-bleed aircraft, what is the pack driven by, and where does it take its air from?
Pack cooling fans
Electric motor, where air taken from outside.
175
What is anti-icing? What is de-icing?
Anti icing: measures to prevent icing from occurring in the engine and on the airframe
De-icing: measures to remove deposits of ice from an aircraft
176
Which surfaces must be kept completely free of contamination? Give 4 examples of this kind of surface. (Basic components)
Critical surfaces
Upper and lower surfaces of wings
Fin
Horizontal stabiliser
177
For which 4 aircraft parts do most CAT aircraft have onboard anti-icing/de-icing for? What 2 areas of the aircraft do not all CAT aircraft have AI/DI for?
Wing, stabiliser and fin leading edges, nacelles
Horizontal stabiliser / fin
178
What is another part of an aircraft that is heated? Why? Contamination of these has caused many fatal accidents.
Sensors, to prevent ice forming on or in them.
179
4 main types of onboard airframe de-icing and anti-icing systems? BEFI
Bleed air: circulated under the skin of leading edges
Electrical heating mats: fixed onto external surfaces of leading edges
Fluid: glycol pumped out of tiny holes onto leading edges
Inflatable boots: use air to expand a boot, thus breaking off formations of ice. DE-ICING ONLY.
180
What material do turbine engines circulate to prevent engine ice?
Circulate hot engine oil
181
3 types of ice detector?
Electromechanical using resonance frequencies: change in resonance indicates ice forming on the sensor.
Mechanical using air pressure: aneroid capsule has a tube which protrudes into airflow. If tube is blocked, pressure inside capsule changes.
Electrical using reference and detector loops: contamination causes large voltage difference between the two.
182
2 propeller de-icing methods? (Just after the basic genre of methods) Where are they applied to the propeller?
Electrical or fluid systems used on individual blades.
183
How are flight deck windscreens heated?
Electrically
184
Through which 3 ways may rain be removed or repelled?(…phobic)
Wipers
Rain repellent fluid squirted into windscreen
Special hydrophobic coatings
185
What fuel do spark-ignition engines use? What fuel must NEVER be used? What fuel do diesel and turbine engines use?
AVGAS
MOGAS
JET-A1 (aviation kerosene)
186
5 ideal qualities of AVGAS? (Good anti-…) LUNGG
Low flash point
Good lubrication
Non-corrosive
Useable across wide temperature range
Good anti-knock properties
187
What are 2 types of AVGAS? What colour is each dyed? What’s eaches’ SG?
100LL (low lead), blue, 0.72
100 (high lead), green, 0.72
188
JET-A1 freezing point? JET-A freezing point? Where are these used? SG of both? What is JET-B used for, why, and should it be used otherwise?
-47°C; -40°C; A1: rest of world; A: USA; 0.8; Arctic Ops, lower flashpoint and freezes at -60°C; no.
189
What 2 “anti” additives does turbine fuel usually have?
Anti-ice and anti-fungal
190
What are the 2 functions of aircraft fuel system?
Store fuel safely
Deliver it under pressure to engines
191
9 components that make up fuel systems? TBLFSCSDF
Tanks: stores fuel
Baffles: prevents sloshing
Lines: deliver fuel
Filters: removes particles
Shut-off valves: isolate supply to engines
Cross-over valves: prioritise fuel feed from one tank
Sump: lowest point in system to where water gravitates
Drain cocks: drain water from sump and other low points
Fuel quality sensor
192
What does a pressure fuel system use to pressurise fuel? Where is this system used (what aircraft)?
Low pressure pumps
All CAT aircraft
193
3 additional components of pressure fuel systems (LPC)? What additional 3 components do more sophisticated systems also have? (PJD)
LP boost pump
Pressure valves
Collector tank
(Pressure de-fuelling system; fuel jettison; density and temperature sensors)
194
By what system can fuel still be delivered to the engine if a booster pump fails? What risk exists if high power settings or rapid accelerations are demanded?
Suction from EDP (engine-driven pumps)
Starvation
195
What system do fuel jettison systems have to prevent all fuel being dumped? From what is the pressure under which fuel is jettison supplied from?
Auto cut-off
LP pumps
196
How do large aircraft change CG position using fuel? Where is fuel moved to/from?
Fuel trim system
Fuel moved from one or more main tanks to trim tank
197
What are used to physically check the fuel contents in each tank?
Drip sticks
198
Why does the lowest part of each tank contain a certain quantity of unusable fuel?
Not accessible to booster pumps
199
3 types of fuel tank?
Drum
Bladder
Integral
200
3 parameters of fuel monitored on the flight deck? What 2 valves can crew operate via the control panel?
Fuel quantity, temperature, flow.
Shut-off and cross-over valves.
201
With what system is refuelling time reduced in commercial aircraft?
Pressure fuelling system
202
A sandwich type structure is often used in an aircraft because of its… (x2)
Low mass and high stiffness
203
Two types of smoke detector?
Optical: uses a light source, detector and labyrinth. Light can only travel along the zig-zag path if smoke is present.
Ionising: air chamber filled with radioactively ionised air, which conducts a current between detector plates. Smoke prevents current flowing, triggering an alarm on flight deck.
204
How does the crew know which cargo compartment has smoke?
Warnings and indicators
205
What gas does built-in fire extinguishing systems use? What is this discharged from and when? How many shots for engine fire extinguishing?
Halon
Bottles, when commanded by the crew
2
206
What is fire protection provided by around engine and nacelles? How many loops and why? When is fire warning indicated?
Alternative method of indicating fire, involving gas pressure?
Fire wires
2 loops for redundancy
Loops subjected to heat change, changing resistance and capacitance. Indication of fire made here.
Alternatively: loops are gas filled. Heat increases pressure, sensed by aneroid capsule.
207
Where do bimetallic fire detectors sense fire? How is fire sensed and stopped?
Specific locations
Each metal expands at different rate, causing sensing element to curl, and close an electrical circuit.
208
In what state is flight deck oxygen and where is it stored? How is its pressure reduced for use? (A kind of regulator)
Gaseous, in a bottle
High pressure oxygen sent to demand regulator which reduces pressure
209
2 selections of oxygen mix in flight crew supply?
Normal: O2 mixed with air and supplied to pilot when they breath (air mix). Progressively more oxygen and less air when cabin altitude increases.
100%: each pilot can override airmix with 100% switch. Prevents smoke inhalation via airmix valve.
210
What happens in terms of O2 supply in masks above a certain altitude? What can help ensure sufficient O2 saturation in the blood?
O2 provided continuously under moderate pressure
Pressure breathing
211
What does smoke hood/mask cover and how long does it provide O2?
Whole head - 15 to 20 mins
Smoke mask - whole face, providing O2 on demand
212
What 2 sources of oxygen are available to cabin crew?
Portable O2 sets
In-seat oxygen supply
213
What do chemical oxygen generators do? What temperature (general) is the byproduct? How is it delivered to passenger masks? Under what pressure? What DOESN’T it protect from?
Combust 2 elements in a sealed container
Warm byproduct
Continuously delivered
Almost no pressure
Mask not sea,ed against noxious fumes
214
2 situations that command passenger masks down?
By crew
Automatically above 15,000ft cabin altitude
215
What does oxygen cause most substances to do? What 2 substances in particular mustn’t be used in or on the system?
Combust very easily or even spontaneously
Oil and grease
216
If the cabin altitude rises (aircraft in level flight), the differential pressure…
Decreases
217
Assuming cabin differential pressure has reached the required value in normal flight conditions, if flight altitude and air-conditioning system settings are maintained, what happens to the mass flow through the cabin?
Mass air flow through the cabin is constant.
218
Which of the following may be incorporated in the aircraft's fuel system
1- Fuel jettison system.
2- HP pump.
3- LP pump.
4- Collector tank.
5- The fuel oil heat exchanger.
6- Tank baffles.
7- Fuel density sensors.
1 3 4 6 7
219
The correct order of decreasing freezing points of the three mentioned fuels is?
Jet A, Jet A-1, Jet B.
220
During level flight at a constant cabin pressure altitude, the cabin outflow valves are?
Partially open
221
Light aircraft may have an electrically driven __________ type of pump to power __________ instruments.
compressor or vacuum; gyroscopic
222
On which principle does the Rosemount ice detector operate?
Vibration
223
What moves piston and in which direction in single acting actuator? What supplies return force? What’s it used for?
Hydraulic pressure moves piston in one direction only
Spring supplied return force
Used as locking device (eg. Landing gear locking/unlocking mechanism)
224
3 types of actuator?
Single acting
Double acting balanced
Double acting unbalanced
225
What moves piston in which direction in double acting balanced actuator? Use (x2)?
Hydraulic pressure moves piston in both directions
NW steering / flight control system actuators
226
How many ports on double acting unbalanced actuator and where? What happens when equal pressure applied through ports?
Two, one each side of piston face.
Different forces on each side of piston because on face has actuator ram attached therefore smaller surface area.
227
What is used to form a hydraulic lock and what is it?
Selector valve positioned so that no flow exists to or from actuator
228
2 general types of selector valve and 2 methods of operation?
Rotary / slide
Electrically / mechanically
229
2 types of hydraulic system?
Open centre
Closed centre
230
Where are open centre hydraulic systems usually used and why? What 2 things do they normally control? Explain what happens when a system wants to be used (can both be at same time?)?
What kind of system is this? What kind of pump used? When is pressure generated?
What’s the system pressure until service selection made?
Small to mid-size aircraft that don’t require large amounts of hydraulic power
Landing gear and flaps (not at same time)
On demand system - spur gear pump used - pressure generated when service required.
Low system pressure until service selection made
231
How are services supplied (arranged) in closed centre hydraulic systems? Why?
What general kind of pump used? Why?
Parallel so operated simultaneously
Variable volume pump so constant pressure supplied.
232
3 types of accumulator?
233
What’s contained inside an accumulator? Effect of excessive pre-charge / too low pressure-charge?
Nitrogen gas and reserve of hydraulic fluid, separated by piston/bladder/diaphragm
Excessive pre-charge: insufficient fluid (too much gas pushes piston down)
Too low pressure-charge: insufficient fluid pressure (too little gas)
234
What are hydraulic pumps driven by and 2 types of pump?
Accessory gearbox of engine (engine-driven)
Constant volume; constant pressure
235
What system does a constant volume pump use? What’s volume of fluid passing through pump determined by? How is output regulated?
Spur gear system
RPM of gears - constant; hence constant volume
Output regulated with auto cut-off valve (ACOV)
236
ACOV? Used where? How does it work?
Automatic cutoff valve, used in constant volume pump.
If pressure exceeds that which spring is calibrated to, open valve opens, causing flow to move round outside through to reservoir.
237
What kind of pump is constant pressure? How is volume varied? How is required pressure delivered? How does pump rotate?
Demand pump, delivering required hydraulic pressure on demand.
Swash plate angled. Pistons end in a sliding shoe which presses against slash plate, increasing cylinder stroke as swash plate leans away.
Required pressure delivered by a control piston tilting the swash plate to the required amount.
Pump connected to driveshaft, so rotates.
238
What does hydraulic motor (rotary actuator) use, and to generate what?
How is this achieved?
Use for these (x2)?
Uses hydraulic pressure to generate rotary motion.
Hydraulic pressure forces down pistons in cylinder block. Linear motion partly translated into rotary motion at swash plate due to piston rods being attached to swash plate.
Operates screwjacks to drive flaps and slats
239
Hydraulic filters
240
Relief valve (hydraulic systems)
241
Shuttle valve
242
Role of restrictor valve and how?
Reduce fluid flow to slow speed of operation
One-way restrictor allows full flow in one direction and reduced in another.
243
Priority valve role and how?
Sufficient flow at all times to primary controls and wheel brakes.
Closes and isolates non-essential circuits if pressure drops.
244
Hydraulic fuse?
Shuts off flow if major leak occurs (low pressure downstream)
245
3 hydraulic malfunctions?
Leaks/low fluid levels (indicated by high temp. or low pressure)
Low fluid pressure
High fluid temperature (reduces lubrications and viscosity, damaging components)
246
PTU?
Each hydraulic system has a hydraulic unit that acts as either a pump or motor depending on where the pressure difference lies. These are connected by a common driveshaft.
If right-hand hydraulic system is low on pressure, a pressure differential between systems forms. Torque is generated on the left-hand side’s hydraulic unit (by the higher pressure), making it act as a motor.
This drives the common driveshaft between the 2 systems, which both hydraulic units are attached to, causing the lower-pressure side’s hydraulic unit to act as a pump, driving hydraulic fluid from reservoir to lines to increase pressure.
PTU stops, mechanically, when pressures of both sides equalise.
247
Oleo components (x2) what does each do?
Gas and oil
Gas compresses, so supports weight
Oil doesn’t compress, so arrests rate of descent
248
Why don’t tubeless tires need tubes?
Rubber is vulcanised (air-tight)
249
Where are i. Constant pressure pumps, and ii. Constant volume pumps, used?
i. Systems where actuator force needs to be proportional to input force, under varying loads. Eg. Flight controls.
ii. Systems where predictable actuator speed from constant flow is sufficient and exact pressure is not critical. Eg. Cargo doors. Pressure controlled by relief valves.
ATPL MOD1
flashcards
Decks in class (19)
# Cards
-
Human Performance LOs354
-
TEM4
-
Principles Of Flight LOs (1)500
-
Meteorology LOs (1)497
-
Instrumentation - Basic LOs232
-
Mass & Balance LOs166
-
AGK - Airframes & Systems LOs249
-
Instrumentation - Advanced LOs346
-
Jack And Dad - Gyros7
-
Air Law - LOs471
-
Air Law - Regulation (EU) No 965/2012 on Air Operations25
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AGK - Electrics LOs146
-
AGK - Engines LOs243
-
Principles Of Flight LOs (2)38
-
Meteorolgy LOs (2)17
-
Engines Ch. 1-9116
-
Engines Ch. 10+126
-
Principles of Flight Ch. 26-32173
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Air Law (conventions, EASA Basics)14
