Airframes Flashcards
focus on the airframe, construction, power, controls
What are the Primary Controls?
Aerilons
Elevators
Rudder
What are the 4 forces?
Thrust
Drag
Lift
Weight
Types of construction
Truss - old school.
Monoqucue - No internal framework. Skin provides structure. Airliners
Semi Monoque - Mix. Does not have internal cross members - uses Longerons and Stringers to strenghen. GA today
Describe parts for Truss construction
Longeron - runs the length
Diagonal Cross Bracing -
Vertical Structural Members
Describe parts for Monocuque construction
Skin - provides structure
Former -
bulkhead -
Describe parts for Semi Monocuque
Skins - usually alumnin alloy
Longeron -
bulkhead
Stringer
Key contructions elements for wings
Ribs - front to back - provide wing shape
Spars - length - provide strength.
Skin - usually alumimin alloy
Stringer - provide rigidity to the skin
Wing strength options
Cantilever - does not use struts
Semi-cantilever - uses struts
What is the tail called?
Describe parts.
describe construction methods
Empenage
Horizontal Stabliser
Verticial Stablisers
Ribs
Strings
Spars
Skin
Describe Airframe integrity ( construction type and possible damage )
Aluminium - Damage will show as corrugation, or rippling.
Also Rust.
Composite - suffer more from distortion. Look for rippling, affected by heat.
Fabric - damage shows as tears. Cracking in paint can show a possible problem underneath.
Describe typical direct action, oleo
pneumatic strut.
Gas Pressure at the top.
Oil Pressure at the bottom.
Consists of
Outer Cylinder
Piston Support
Inner Cylinder
Metering value ( tapered )
As the wheel is pressed up, the inner cylinder slides up, displacing the oil - which is metered due to the tapering
What is a torque link on a nose wheel?
On the nose wheel strut.
Prevents the inner cylinder from rotating
How do brakes work?
Usually disc brakes and hydrolic.
Pressure is transmitted to the slave cylinders - which pushes the hydrolic fluid compressing the brake pads onto the Rotor
Name the secondary flight controls
Vertical/Horizontal Trim Tabs
Flaps
Spoilers
What does it mean to say controls are aerodynamically balanced?
The controls are designed to reduce the effort on the pilot to move controls.
Name 3 examples of aero dynamically balancing
Insert Hinge
Horn Balance
Balance Tab
What is Flutter?
Happens when the airflow causes the wing to change direction faster than the control surface ( aileron )
Usual cause is when the hinge point is forward of the CG
NOTE: If the hinge point is behind the CG/mass balance no mass balancing is required.
the two ways to reduce/remove Flutter?
More rigid wing structure
Mass balance the control surface
CG must be forward of the hinge point to mass balance
Ways to mass balance?
Easily accomodated on:
Inset hinge
Horn hinge
For others it must be placed outside the control surface
4 Ways to reduce pressure on controls?
Not triming, ways in construction to reduce pressure
Servo Tab/balance/control tab - flight control moves the tab, which uses airflow to move the main surface.
Horn style hinge - Part of the control surface protrudes upwards in to the air flow
airflow gap - the hinge allows air to flow over the top of the control surface.
hydrolic controls - uses hydrolics instead of cables. And techniques such as jackscrews
Which way to the following move?
Trim Tab
Servo/balance/control tab
Anti-Balance Tab
Trim Tab - control independently.
Moves opposite to control surface ( the control surface moves to neutral again ).
Servo/balace - moves against the direction of the control surface. Reduces required stick force.
Anti-balance tab - move in the same direction as the control surface
Increases required stick force. Used to make controls heavier.
What control surfaces have tabs for trimming?
Ailerons - in GA, usually fixed. required mechanic
Elevators - pitch trim. All aircraft. Large airlines may adjust full elevator surface.
Rudder - yaw trim.
What are the 4 flap types?
Split flaps - old school
Plain - flap forms part of the wing surface when raised.
Fowler - Increases the wing surface ( airliners )
Slotted - allow airflow through. ( GA )
What are spoilers?
Name the 3 uses
Create drag.
Air brakes ( used symetrically ) - allow descent without speed increase
Roll assist ( used asymetrically )
Ground ( used on ground ) - to prevent the wings creating lift.
Why do alierons move different degrees?
Called differentail ailerons.
This is to prevent adverse aileron drag. ( opposite yaw )
Which results in the upper wing having more drag, and slowing - therefore yawing in the opposite direction.
What causes adverse yaw?
Deflections means that:
Upper wing will have more drag, as alieron is deflected downwards.
Upper wing lift is moved slight backwards ( due to Angle of attach )
Describe the main parts of a fuel system
For Gravity
For Fuel Pump
Not the engine parts - just fuel system.
Gravity
tanks
Fuel selector value
Strainer
Primer
Carbrurator
Fuel Pump
Electric Pump ( start and back up )
Engine driven Pump
Strainer
Primer
Selector Value
Carbrurator
What is octane?
What does it mean when there are 2 octanes? ( like 100/130)
Fuel rating. Higher octane = high anti-detonation
100/130 - means 100 when lean mixture and 130 when rich mixture
What is added to prevent knocking ( detonation )?
And max parts
tetra-ethyl lead ( Tel )
AVGAS - 1 part per 800
LL - 1 part per 2,250
What are the colours of fuel?
MOGAS 91 - Purple
MOGAS 96 - Yellow
100LL - Blue
100/130 - Green
115/145 - Purple
Jet Fuel (Jet A1) - Straw coloured (Light Brown) DO NOT USE
What are the components of fuel
ISO Octane
Heptane
% of octance is the rating.
What does lead do to spark plugs and what is added to manage the impact?
Lead can cause lead oxide to form on the eletrodes of the spark plugs - resulting shorts.
Ethlyene Dibromide is added to the fuel
What is specific gravity?
Density of the fuel
Compare to water ( specific gravity of 1 ) at standard temp ( 15 degrees C )
Lower is better
Difference between Alternator and Generator?
( and advantages )
Alternator
Magnetic field rotates, stator is static
Creates AC
Requires Recifier to turn AC to DC - which is circuit using diodes
Weighs less than a generator
Requires battery power to energise it.
Produces consistent voltage even at low RPM
Easier to maintain.
Generator
Magnetics are static, coil rotates.
Produces DC current.
Does not require a battery to energise.
They are heavier, and generally Alternator is preferred.
How does a Circuit Breaker work?
Key component is the Thermal Element.
If there is excess current, the thermal element will deform, seperating the latch.
Once the current is cut, the Thermal Element will return to orginal position.
Power is re-established by pushing the breaker in.
Main parts of a Circuit Breaker?
Thermal Element
Latch Mechanism
Main Contacts
Control Spring
In a Trip-Free Circuit breaker - there is also a trip free switch.
What is a trip free circuit breaker vs non-trip free.
Trip-Free
Means that if the push button is held in electricity will not flow if the thermal element is deformed.
This is due to the Trip-Free Switch - attached to the Latch.
Describe the key parts of battery cell?
How do they make a battery?
Electrodes
Electrolytes ( usually Sulphuric Acid )
Cells are combined in series to make a battery.
What happens when a cell discharges?
And what is the EMF at full discharge
Plate faces become coated with a white residue of Lead Sulphate
Cell is considered to be fully discharged when it’s EMF ( Electro Motivate Force ) is reduced to 1.8V
Normal GA battery?
6 cells
Fully charged = 13.2 volts
Fully discharged = 10.8 volts
What does the anmeter show?
Current flowing to or from the battery.
-ve means from the battery
+ve means to the battery.
This means that -ve in flight = bad.
How many busbars and what do they do?
Two.
Primary
Lights
Pumps
etc
Avionics
Instruments
Avionics
etc
If the alternator is working as expected, what should we see?
Small +ve on Anmeter
Small Load ( assuming everything else is off )
