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Structures Flashcards

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1
Q

Best way to prevent the formation of corrosion

A

Eliminate one of more of the basic requirements

  • remove the electrical potential difference within the metals
  • prevent the introduction of an electrolyte
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2
Q

Types of metallic coatings

A

Cladding: pure aluminium rolled onto aluminium alloy

Electroplating: plating cadmium, chromium, nickel or zinc on steel

Metal spraying: aluminium or zinc on steel

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3
Q

Surface conversion coatings

A

Anodising of al alloys

Alodine 1200, 1120 pens

Chromating of magnesium alloys

Phosphating of steel

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4
Q

Organic coatings

A

Paint
Jointing compound
Sealant
Cpcs

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5
Q

What are cpcs

A

Used as a secondary protective coating to the primary protection. Provided by paint, chromate primer, alodine anodising and plating

Oil/wax Base as a means of retarding and preventing corrosion

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6
Q

Types of cpcs

A

Type a- short term. Water displacing. Thin film. Base

Type b- medium term. Soft film. Common. Good penetrating properties

Type c- long term. Hard film. Low penetrating properties. Top coat.

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7
Q

Handling practices and husbandry

A
  • Maintain adequate cleaning/preservation programme.
  • Wear approved footwear and ensure soles are free from embedded abrasive material
  • Treat corrosion and failure of protective coatings as often as possible
  • Lubricate exposed mechanical parts regularly
  • Store removed panels/cooking’s safely to prevent them being blown and scratched
  • handle fuel hoses/ equipment carefully to avoid scratching Ac
  • drain/ventilation holes are free from obstructions
  • fit protective covers
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8
Q

Handling of al alloys

A

1) wear ppe
Gloves, overalls, steel toe/suitable footwear
2) seeks assistance if handling large sheets
3) clean work area

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9
Q

Storage of al alloys

A

1) store on edge to avoid damage to surface. But avoid damage to edge
2) take care of protecrivecoating
3) cut from one edge only. Take care to avoid removing identification markings
4) mark out in the most economical way prior to cutting
5) take particular care when inserting sheets into racks. Avoid scratching other sheets

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10
Q

Repair manuals and references

A

Specific Ac structural repair manual 13,-98
General Ac structural repair manual
General engineering manual
Manufacturers material and fastener data handbooks

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11
Q

Procedure for corrosion removal

A 
Ref:srm 
1) remove surface coating
2) consult srm for damage limits 
Measure corroded area
Discuss with supervisor 
Remove
3) measure damage after removal, repair if necessary
4) apply appropriate treatment to area affected
5) reapply surface coating
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12
Q

Types of surface coating removals

A

Chemical

Mechanical

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13
Q

Surface coating removal. Non powered mechanical

A 
Abrasive mats(scotch rite) 
Abrasive paper
Abrasive cloth
Wire brush 
Tube brush
Pumice powder 
Metallic wool 
scrapers
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14
Q

Surface coating removal. Powered mechanical

A 
Al oxide discs 
Scotchbrite discs
3m radial bristle discs 
Mediablasters 
Rotary file (burrs) 
Linisher (dynafile) 
Flapper wheel
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15
Q

Ways to measure damage for corrosion removal

A 
Depth garage 
Optical depth gauge 
Ndt 
Fluerscent dye penetrant 
Eddy current 
Ultrasonic
Radiographic 
Straight edge feeler gauge
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16
Q

Repair manuals

A

Specific aircraft structural repair manuals
general aircraft structural repair manual
General engineering manuals
Manufacturers material and fastener data handbooks

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17
Q

To- 1-1a series

A

To1-1a-1 general manual of structural repair
To1-1a-8 aircraft structural hardware
To 1-1a-9 aerospace metals general data/usage

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18
Q

Ap 101a series

A

Ap101a-1401-1 reverting process used on Ac

Ap101a-1402-1 aerospace sheet metals and fasteners

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19
Q

General engineering manuals

A

591
6003-1, Ac and aeronautical equipment maintenance- general orders and procedures
6000-1, Air Force maintenance orders
6005.042-1.1-3 engineering practices and procedures- ac and avionic systems cleaning and corrosion prevention

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20
Q

Identifying American al alloy

A 
Four digit designation
Clad bare
Temper
Thickness
Fed specification number
Manufacturers name
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21
Q

4 digit designations al alloys

A 
1-99% or higher pure al 
2-copper
3-manganese 
4-silicon
5-magnesium
6-magnesium and silicon
7-zinc
8-others
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22
Q

Methods of harden ing al alloy

A

Cold work
Rolling, forging, extrusions

Heat treatments
Solution heat, natural age, artificial age or precipitation heat treated

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23
Q

Hardness designators

A 
Cold- h1- strain hardened 
H2- strain hardened and partially annealed
H3- strain harder and stabilised
Heat- 0- annealed
W-solution heat treated (unstable) 
T3-solution HT then cold worked
T4 SHT then naturally age hardened 
T6 SHT then artificially age hardened
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24
Q

Go do we know which sheet to use?

A

Stated in drawing

Stated in srm/ repair scheme

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25
Characteristics of al alloy sheets
``` Large Expensive Difficult to handle Sharp edges Easy damaged Major load carrying member ```
26
Storage of al alloy sheets
Store on edge to prevent damage to surface, but avoid damage to edge Take care of protective coating Cut from one edge only- don’t cut off identification markings Mark sheet in most economical way Take care when inserting sheets into racks to avoid scratching other sheets
27
Handling precautions for al alloy sheets
Ppe to be worn. Gloves, boots, overalls Seek assistance if handling large sheets Clean work area
28
Sphere of influence is what
5d | The area effected by the clamping force of each installed rivet
29
Edge distance?
2d minimum, specific limits in srm. | Distance between the centre of a fastener and a edge of the structure
30
What’s the pitch?
Distance between adjacent rivers centres in the same row. Commonly 4d
31
Transverse pitch of spacing?
Distance between the centres of rivets in rows. Commonly 4d
32
Clearence still does what
Allow for river expansion in the hole Prevents burrs Prevents hold damage and skin by killing Prevents the protective coatings being removed on rivet installation
33
Drilling aids
Drill blocks | Bushings
34
Types of reams
Hand | Machine
35
Pilot holes- | Pre drill-
Used to locate new holes | Used prior to drilling final or clearance
36
Flush fasteners used where
Aerodynamically smooth skin surface is required | The fastener head may interfere with adjacent structure
37
Methods of flush fasteners
Countersinking | Dumpling
38
Why would u use countersinking
``` Used on thicker material Quick and easy Cheap Used where dimpling is impractical or not possible Cons-weakens material strength ```
39
Factors effecting countersinking
Diameter of fastener head Height of the fastener head Angle of fastener head Dimensions of fastener head can be found in Ac srm, 6005.001-1 or manufacturers fastner handbook
40
Common countersinking cutting bits
Multi fluted, un piloted Piloted Microstop
41
Things to note about multiflute not and piloted csk bit
Mfb-less likely to chatter because of the many cutting faces Piloted- uses the pilot to guide the cutter, helps to keep concentric
42
Things to note about microstop countersink
Adjustable to depth increments of 0.001” Gives accurate depth control Negates requirement for frequent stops to check countersink depth
43
Material thickness limits for countersinking can be found where
Ac srm | Snap 6005.001-1
44
Dumpling used when | Also known as what
Form countersinking Thinner material Used where cut countersinking is impractical or not possible Gives greater shear strength at fastner joint
45
Things to be aware of when dumpling a piece of material
Male and female dies match and are the correct size Dumpling pressure is correct, otherwise causes warpages Dumpling pilot hole is correct dimension. Critical to ensure the simple is concentric to the hole
46
Types of dimpling
Coin Radius
47
Formed rivet terms
Manufacturers head Shank Shop head or tail
48
Grip= | Allowance=
GL= same as the material thickness A=protruding length of the unformed rivet required before forming. Normally 1-1.5d D=rivet shank dia
49
Total rivet length =
Grip + allowance
50
Shop head dimensions after riveting
0.5d
51
Head shapes
Countersink Universal
52
Solid rivet identifications
A dimple- ad 2117 | Dd-double dashes 2024
53
Solid rivet part numbers An 426 ad 4-5 Ms20470 ad4-5
``` Catalogue method Headstyle -426 countersink, 470 universal Alloy designation Diameter in 1/32 Length in 1/16 ```
54
Methods of forming
Hand rivet Squeeze rivet Reaction rivet
55
Reaction rivet
Rolling Pneumatic air hammer Snaps Dollies or bucking bar
56
Solid rivet faults
``` Cut head Sheared head Open head Damaged skin Snap damage Cracked shop head Formed between skins-0.003” or less is ok Cocked head-0.002 Opened edge-0.010 Under/over formed shophead Offset shophead ```
57
Servicae shophead dimensions
0. 3-0.5d | 1. 4-1.5d
58
Safety precautions when operating a snap
Don’t operate fun without safety spring fitted on snap Disconnect air supply when removing or replacing snap Wear ear protection Prior to riveting shout a warning to inform others of hazard Always have a snap on rivet or wood when operating the gun
59
What is a blind rivet When is it used Advantages
Rivet that can be fitted when access from only one side is possible - when access is no longer available due to further construction - when it would not be cost or time effective to gain access to use conventional fasteners * fitted blind or from one side * fitted by one person
60
Blind rivet substitution.
Not a direct shbsititute forsolid rivets. Used only iaw ac srm(-3) and 6003-1 substitution chart
61
Blind rivet terminology
``` Mandrel or stem Driving anvil Locking ring Tail or bulb Body or sleeve ```
62
Generations of blind rivets
Pull thru-cherry pull thru Friction locked-self plugging. Tucker pop Mechanically locked, self plugging- huchloks, cherryloks, Olympicloks. Self plugging mechanically locking mandrel bulged type- cherry max, huck clinch, huck max
63
RNZAF blind rivet policy
``` Laid out in NZ ap 6003-1 leaflet d1 Tuckerpop Olympic lok Cherry max Cherry pull thru Huckclinch/huck max Huck blind bolt & jo bolt (heavy duty structural fastner) ```
64
How to get correct length for grip length for blind bolt
Grip length gauges | Grip length chart
65
Cherrymax/ huck clinch nominal and oversize indicators
Gold driving anvil-nominal | Silver driving anvil- oversize. Oversize is 1/64” bigger than the actual shank dia stated
66
Tuckerpop identification | AGS2051630BS
Ags2051-rivet type, material headshape 6-dia in 1/32” 30-rivet length in 1/100” Bs-breakstem
67
Cherrymax identification | Cr3213-6-5
Cr-cherrymax rivet 3213-material, nom/over, headshape -6-dia in 1/32” -5-grip length in 1/16”
68
Cherrymax tooling
Hand Hydraulic hand Pneumatic hydraulic
69
Huck clinch identification | Hc3213-6-5
Hc-huck clinch rivet 3213-material nom/oversize -6-dia in 1/32” -5-GL 1/16”
70
Headstyles for jo bolt | Made of what alloys
Hexagon protruding bead 100* flush head 100* flush billable head Steel and titanium alloys
71
Installation inspections for jo bolt
Looseness-checked with driving tool nose adapter, torque wrench Head flushness- no more than 0.010” Break off limits-go/no go gauge Gaps under head-0.005” + reject, 0.004” around 40% of circumference or less=acceptable Collar inspections-where possible
72
Structural fasteners in rnzaf
Jo holy | Huck or cherry blind bolt
73
Blind bolt identification | Ms90353-06-05
Ms90353-pn, head shape, material, nom/over - -double action, S single action U unimatic 06-dia in 1/32” 05-GL in 1/16”
74
What does the green dye on a blind bolt indicate
Single action installation
75
Lock bolt identification Pin- NAS1466-5 Collar-NAS1080-6
NAS146-pn, material, head shape, bom/over, stump/pull thru type 6-dia in 1/32” 5-GL in 1/16” NAS1080-pn material 6-collar dia in 1/32”
76
How do you inspect a lock bolt
With a go no go gauge
77
Types of hi loc pins
Hi lox Pin Hi tigue pin
78
Hi tigue pin fatigue resistance benefits
``` Burnishes the hole Preloads the hold Cold works the hole Sizes the hole Protects surface coatings Lowers the installation loads ```
79
Hi loc pn identification-part numbers Pin- HL50-6-6 Collar-HL90-6
HL50-pn material bead shape nom,over HLT=hi tigue 6-dia in 1/32” 6-GL in 1/16” HL90-PN material -6-dia in 1/32”
80
Hi loc identification-head markings Pin- HL18-6-6 CollarHL70-6
HL18-pn material, head shape, nom/over, HLT-hi tigue 6-dia in 1/32” 6-GL in 1/16” hl70-pn material 6-dia in 1/32”
81
What is the preferred pin fastner for general repair work in the RNZAF during design of modifications and repair schemes
Hi lock
82
Ac loads
Aerodynamic loads Inertial Concentrated Engine
83
Types of composites
Ceramic | Fibre reinforced plastics
84
Types of FRP
Glass fibre Carbon Aramid/Kevlar Boron
85
Alternatives to al alloy
High strength steel alloys -carbon Stainless Molybdenum Titanium alloys Magnesium
86
Types of bulkheads
``` Structural Pressure Fuel Fire Cantered ```
87
Typical damage to Ac structure
``` Warpage Fatigues Oil canning Buckling Corrosion Impact damage ```
88
Typical damage to Ac composite structure
``` Substructure damage Voids Ingress of water and absorbsion Disbonding Delaminatiln Barely visible impact damage Cracking/brittle fractures ```
89
Methods of ndt
``` Magnetic particle detection Ultrasonic Fluescent dye penetrant Visual Eddy current Radiography ```
90
3 conditions needed for corrosion to exist
Electrical potential difference between anode and cathode Metallic connection between anode and cathode Continuous liquid path (electrolyte)
91
Factors influencing rate of corrosion
``` Type of metal Heat treated Grain direction Anode and cathode surface area Presence of electrolytes and degree of acidity Salts Temperature Mechanical stress Fatigue ```
92
Corrosion prone areas-accessible
``` External skin Engine inlet Engine exhaust Wheel wells/landing gear Battery compartments/cents Lavatories/food service areas ```
93
Types of forms for transparent plastic material
Simple curveformjng Compound curve forming
94
Types of compound curve forming
``` Stretch forming Mal and female die Vacuum forming without forms Vacuum formwith a female Sawing ```
95
What do you drink a plastic transparency with
Unibit for windshields and windows
96
Repair of windows/windshields
Temporary-fly to a location where it can be replaced. Stop drill with no 30drill. No40 half inch from the edge Permanent-stopdrill no30. Hypodermic syringe and needle to fill the crack with ethylene dichloride
97
How are acrylic plastics joined together
Ethylene dichloride
98
Types of construction
``` Integral Bonded Sandwich -honeycomb -end grain bulsa -plastic foam ```
99
Defects for laminated glass
Scratches Shattering Delamination Cracking
100
Defects for plastics
Scratches Crazing Cracking Distortion
101
Ac locations using reference line sys
Fs-lengthways from a reference point along the fuselage Ws-measured along the span of the wing with zero the centreline of the fuselage Bl-left or right of the centreline of fuselage Wl-measurement of height from horizontal line fixed below the bottom of the fuselage XYZ-longitudinal,lateral,vertical axes as xyz and is identified by the manufacturer
102
``` Define skin Frame Former Stringer Bulkhead ```
Smooth outer covering of the af -transverse structural member, provides aerodynamic shape and rigidity Lighter than a frame -a long continuous memberthat assists skin load carrying to other structural members Major transverse membersin the fuselage or Wing and other structure
103
Lightening hole. Define Longeron Stringer
A hole in a member to decrease weight with strength maintained by flagging around the hole Main longitudinal structural member. Heavier than a stringer A long continuous member hat assists skin load carrying to other structural members
104
Stiffener | Doubler
Normally a strip or beam attached to a sheet to resist load normal to the surface. Short component used to stiffen a localised area A piece of sheet or strip placed against Ac skin to provide stiffness it additional strength
105
Cantilever construction Spar Cap Boom
Supported internally by structural members assisted by the skin The main structural span wise member of an aerofoil The longitudinal member atthe top and bottom of a beam often called a boom Longitudinal structural member
106
Web | Rib
Vertical member of a beam, spar or other length of a wing or fuselage providing strength necessary to resist shear stress and keep upper and lower booms apart -structural crosspieces combining with sparks and stringers to make the framework of wings, ailerons, elevators, riders and stabilisers
107
Nacelle Cowl panrl Fairing
Any auxiliary structure that encloses the power plant or other equipment - surrounds the power plant or other equipment circumferentially and improves airflow - a smooth covering over a joint or a junction in an Ac structure providing a smooth surface for the airflow reducing drag
108
Access panel | Structural/stressed panel
A seperate or distinct portion of the surface of an Ac structure earily removed -similar to access panel but more substantial design and iaw mm or srm ay needyk Be fittedprior to Ac movement or jacking
109
Fillet | Radome
Aerodynamic fairing giving radius atthe junction of two surfaces -protective covering and aerodynamic fairing overtaxation antenna
110
Impact damage to composite materials
``` Substructure damage Voids Water ingress and absorption Disbonding / delamination Barely visible impact damage Cracking/brittle fractures ```
111
Classes of structural damage
Negligible Repairable Replacement
112
Ac inspection types
Zvin Gvin Corrosion
113
Inspection tooling equipment
Light Magnification Mirrors
114
Function of ndt
Method we are able to use to detect flaws without affecting the serviceability of the material
115
Define corrosion
Deterioration of metals that result from an electro chemical reaction between a metal and its environment. Corrosion occurs due to the tendency for metals to return to their natural state
116
Three conditions that must exist for corrosion
Difference in electrical potential between anode and cathode Metallic connection between anode and cathode Continuous liquid path
117
Factors that influence corrosion
``` Type of metal Heat treatment Grain direction Dissimilar metals Anode/cathode surface area Presence of electrolytes and concentration Salts Oxygen Temperature Mechanical stress Fatigue Length of exposure ```
118
``` Corrosion looks like- Al and al alloys Magnesium alloys Iron/steel Copper alloys Cadmium Stainless steel Titanium ```
``` White-grey powdery particles White-grey powder fluffy particles Reddish brown scale Blue/green powdery particles White powder deposite Red brown or black stain No visible corrosion at low temp ```
119
Accessible forrosion prone areas
``` External skin areas Eng Inlet Eng outlet Wheel wells and landing gear Battery compartments and vents Lavatories and good service areas ```
120
Why corrosion of lavatories and good service areas
Organic materials are highly corrosive Food waste traps water Disinfectences are corrosive
121
Inaccessible areas corrosion prone
``` Electronic equipment Welded areas Fuel tanks Control surface recess Piano hinges Bulge areas Landing gear boxes Eng mount structure ```
122
Ac sealants do what
Aid structural integrity Contain vital gases and liquids Prevent the ingress of damaging liquids and gases
123
Sealant type for each application is contained in what publication/s
Ac srm. | Authorised sealants are listen in the nzap 6005.009-1
124
Sealant construction is made of what compound
Two part polysulphide rubber compound and made to various different specifications
125
Sealant part number | PR1440GB2
``` Product number G-Increased soluble chromate content. Helps prevent corrosion B-method of application A-brushable B-sealant gun/spatula C-faying surface sealant sprayable 2-application time in hours ```
126
Reliving sealants and adhesives?
``` Condition of container -leakage, corrosion, degradation Condition in container -separation,layering, settling Application of properties -lumps, foreign matter, viscosity Drying or cure time Appearance ``` If yes, extend by one half of initial assigned shelf life. 591, 7.17
127
Non extendable shelf life of sealants
- Not been stored in a controlled temperature environment - Products marked with an “N” in their relief code column - Locally purchased products - Those is aerosol containers - Those with no DOM
128
Surface preparation sealants
Remove old sealant using a specialist type scraper Thoroughly clean and degrease area Mask around area to be sealed
129
Sealant CHeck prior to mixing
- Self life - separation of contents that may prohibit a homogenous mixture being achieved - Degradation of container - discolouration of Base compound or accelerator - hardness or tackiness - leakage from container
130
Sealant application methods
Nozzle Polythene tune Spatulas
131
Two part sealants are mixedhow
Iaw instructions on the semkit cartiridge General instructions
132
Sealant handling precautions
``` Avoid eye contact Avoid skin contact Avoid breathing vapour Ensure adequate ventilation Store sealants correctly ```

Aircraft mechanics (14 decks)

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