Given Questions Flashcards
How is steel in aircraft classified?
Ferrous or non-ferrous
What is the ability of a material to withstand cutting?
Hardness
What is the purpose of refrigerating 2017 and 2024 rivets after heat treatment?
To retard age hardening
What does 2024-T4 stand for?
2024 = DD aluminium-copper rivet
T4 = Solution heat treated and naturally aged.
What is precipitation heat treatment?
Precipitation heat treatment or artificial aging
When an aluminium alloy has been solution heat treated, it gains its full hardness and strength by natural aging, but this process may be expedited and increased by returning the metal to the oven and heating it to a temperature much lower than that used for solution heat treatment. It is held at this temperature for a specified time, then removed from the oven and allowed to cool in still air. Precipitation heat treatment or artificial
aging increases the strength and hardness of the material; decreases the
ductility; and has little to no effect on corrosion resistance.
Why is cladding used in Aluminium?
To make it more corrosion resistant
What does Alclad consist of?
Pure Aluminium
What does a ferrous material contain?
Iron
What is the raw material used for Aluminium?
Bauxite
The rate at which mixed sealant will cure depends on what?
The curing rate of mixed sealant varies with temperature and humidity
For
example, at temperatures below 15°C curing is extremely slow. However, a
temperature above 21°C typically results in a faster curing time. A
temperature of 25°C with 50% relative humidity is the ideal condition for
curing most sealant.
Dacron is used for what?
Dacron is the registered trade name of the polyester fibre/yarn.
Polyester is petroleum made synthetic material that is used to manufacture economic fibres that are strong, reliable and durable for airframe covering.
A chopped strand mat is weaker than woven mat because?
Chopped strand is not as strong as woven cloths because the fibres are short.
What is the definition of shelf life?
The length of time that a resin can be stored before it is used is known as the shelf life
(2 years)
What is the definition of pot life?
The amount of time that the resin remains usable after the catalyst is added is called the pot life
(30 mins)
Hexagonal honeycomb is used for what types of forces?
Out of plane compression and shear
What is the most effective way to apply pressure to a repair?
Vacuum bag??
What type of wood has a parallel grain structure?
Laminated wood
What type of fabric is polyester?
The two main types of Man made fabric used on aircraft is polyester and glass fibre
What type of fabric is linen?
Natural Fabric
(Cotten and linen)
Where is unbleached Irish linen used?
Used where strength is the most important factor
What are waxed threads used for?
Waxed threads are used for hand sewing, but waxed and un-waxed types are covered by the same specifications from suppliers.
Core sandwich panel needs to resist what force?
What does AFRP stand for?
GFRP
CFRP
Aramid Fibre Reinforced Plastic (Kevlar)
GFRP = Glass Fibre Reinforced Plastic
CFRP = Carbon Fibre Reinforced Plastic
Why are reinforced plastics used?
To improve the strength and stiffness of plastics.
They are also much lighter than metals.
Explain 3k-70-PW?
3k = 3000 filaments per bundle
70 = 70 microns in each filament
PW = Plain weave
(Micron = 10^-6)
What is the easiest way to check a bonded structure for delamination?
Coin Tap test
What composite material is black?
Carbon Fibre Reinforced Plastic
What wood comes from dicidious trees?
Hard wood
What is the maximum slope of grain in wood?
1:15
Cotten is what type of fabric?
Natural fabric
What is the advantage of using x-ray to identify defects in composite parts?
How is the testing of fabric covering achieved?
Testing of an aircraft’s fabric covering can be achieved by using a variety of methods, including a portable,
calibrated fabric tester
A metal that doesn’t corrode easily is called what?
Noble metal
Corrosion caused by inadequate heat treatment is what type of corrosion>
Intergranular Corrosion
How do you detect intergranular corrosion structure in aluminium alloy?
White, powdery deposit starting n surface as pitting corrosion????
What is the most common agent to cause chemical corrosion in a metal?
Spilled battery acid or fumes from batteries
Residual flux deposits resulting from inadequately cleaned, welded, brazed or soldered joints
Entrapped caustic cleaning solutions
Metals that lose electrons easily are called what?
Active metals
Corrosion that is caused by electrolyte corrosion is a result of what?
Two dissimilar metals
(Galvanic corrosion)
Where does Microbial corrosion occur?
Microbic growth occurs at the interface of water and fuel where the fungus feeds on the fuel
How do you treat and prevent that type of corrosion (microbial)?
Microbial corrosion can be minimised with a maintenance program which includes frequent sump draining, tank inspection, total removal of microbial growth and applicaiton of bio-cide with ‘soak periods’
Question about most corrosive elements to least corrosive , that diagram
Should know most cathodic to most anodic?
Unified inch threads above 1/4 ‘’ diameter are measured as?
Above 1/4 ‘’ diameter, the nominal sizes are given as fraction of an inch
Where are type ‘B’ self tapping screws used?
Used interior for non-structural applications
Curtain rack in cabin
How are type ‘B’ self tapping screws identified?
A blunt point and a finer thread than type ‘A’
Where and why would you use a threaded taper pin?
Taper pin is used to produce a tight fit in a reamed hole for applicaitons in shear with no loose motion or play
Give a practical example of V threads and where you would find them?
Mostly used for attaching aircraft parts e.g Aircraft nuts and bolts
V for ‘Very’ common
What is the definition of a recess on the head of a bolt?
Indentation in the head is used in the identification or to drive the bolt
What is the main advantage of using circlips?
Are circlips reusable?
The main advantage is that they reduce weight and are a cost saving device due to simplicity in design
(Reusable)
Where are titanium rivets used?
What is the most common screw thread used in aircraft hardware?
‘V’ thread
What type of thread produces a one-sided force?
Buttress thread
What type of screw has a blunt point?
Type ‘B’
How do you identify a close tolerance bolt?
A triangle with an ‘X’ in it
What materials are split pins made from?
Split pins are the same thing as cotter pins
Corrosion resistant steel or cadmium plated, low carbon steel
How do you determine the length of a split pin/cotter pin?
Split pin/cotter pins are measured from their short leg
An aluminium alloy rivet with no head marking is made from what?
1100 Aluminium Alloy
What type of aluminium alloy is used in ‘AD’ rivets?
2117
Recognised by a dimple (indented dot)
Which blind rivet has a driving rivet?
Cherrymax Rivet
How do you measure screw thread pitch?
The distance between a thread crest and an adjacent thread crest
Left hand thread tightens when turned in what direction?
CCW
What is thread depth?
Distance between Thread crest and adjacent thread root
What is an ‘AN’ bolt?
Air force Navy bolt
Why are wing nuts used?
Used for inspection panels or maintenance areas as are removed easily without tooling
What head marking do aluminium alloy bolts have?
Two dashes
Aircraft bolts/screws are manufactured to what class fit?
Class 3 = aircraft bolts
Class 2 = aircraft screws
Locking devices, which ones can be used once and which more than once
How should a flathead pin be installed?
Flathead pin (Clevis pin) is usually installed head up so that if the cotter/split pin should fail, the pin will remain in the same place (gravity)
Can a spring washer be reused?
They may be used again as
long as the washer retains the spring tension.
A rivet with 2 dashes on its head signifies what type of rivet?
What is a rivet grip length measured in ?
MS20470AD6-4
Diameter of grop lengt of this rivet is?
MS20426AD4-4?
What dos MS20426 signify?
A rivet with a raised cross on its head is what type of rivet?
What is the main advantage of having Carbon in steel?
Increases hardness and strength
What is an allotropic metal?
Allotropic means that it can exist in more than one type of lattic structure e.g BCC and FCC
What is SAE 4130 Steel? (Break down digits)
41XX = Chromium-Molybdenum
1 = Plain Steel
(0 in this second digit place would inidcate no alloying element)
30 = 0.3% Carbon
Describe Solution Heat treatment?
Some alloys may be hardened by heating them in a furnace until they have reached a specific temperature throughout ( Different alloys and indeed thicknesses will have different soak times) and immediately quenching them in water.
Hardness properties dont exist straight away and may take some time
Can then be either naturally aged or artificially aged.
What is Ti 811?
Titanium aluminium alloy
Ti - 8Al - 1Mo - 1V
Very high stength but hard to work with
Used on supersonic jets
List the three key properties of a reinforced plastic
Strength
Stiffness
Impact Resistance
(Lightweight compared to metal)
List 3 classifications of plastic
Thermosets
Thermoplastic
Elastomer
What equipment is used for hot curing?
Special curing equipment
Catalyst only becomes active when heated
More Resin = faster curing time as insulates better
List three main types of honeycomb material
Aluminium
Glass Fibre
Nomex
Kevlar
List three safety precautions when using resins
- Skin contact - difficult and harmful to remove resin from skin
- Dermatitis - inflammation of skin (gloves/barrier cream prevents)
- Inhaling fumes - Wear mask
What is a positive ion?
(Cat)ions are (pussitvely) charged
Cations
What is the most corrosive metal?
Magnesium
List some factors that influence corrosion
Identify the material of which the bolt is made when its head is makred with a/an:
- Cross or Asterik
- Single dash
- Cross or asterik = AN Standard Steel bolt
- Single Dash = AN Standard Steel bolt ( corrosion resistant)
Explain the bolt part number:
AN4C6
AN = Airforce Navy
4 = 4/16 ‘’ diameter
6 = 6/8 ‘’ shank Length
C indicated Stainless Steel bolt
A = shank of bolt undrilled
No letter means shank is drilled
H = Drilled head bolt