02 airframes notes (atpl)

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    Ground School Day 1 12/29/2015

    Types of load

    Static: Steady load of some intensity throughout

    Dynamic: Varying intensity and direction for

    Cyclic:

    StressStress is the internal force per unit area inside a structural part as a resultof tension: ension! Compression! orsion! Shear! "ending

    Wing (Main Plane)Stress - Bending#n ground: $ings droop due to fuel! engine and its o%n %eight& 'ppersurface under tension and lo%er surface under compression&(n flight: $ings )end up%ards due to lift forces& 'pper surface no% undercompression and lo%er surface under tension&

    o mitigate %ind )ending stress in flight

    $ing mounted engines

    *uel 'sage: Centre tan+ then %ing tan+s ,in)oard then out)oard! if

    applica)le-

    .ileron 'p *loat: Crude drag inducing deice

    Pressurization Stressoop ,adial- and .ial stress

    Stressing a material may cause it to change its shape or to deform&his change or deformation is +no% as S.(3&(t %ill go )ac+ to its original dimension proided the change is %ithin its4lastic imit&

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    Station numbers

    Attachment methodsieting! $elding! .dhesie )onding! "olting!6inning

    Material Properties

    4lasticity

    .)ility to change its shape reersi)ly %hen su)7ected to certain

    loads or forces

    6lasticity ,or Ductility-.)ility to deform irreerisi)ly under force or load

    Stiffness / igidity.)ility to %ithstand reersi)le deformation under load

    Strengthesistance to damage

    !imit load

    Design limit load8aimum load the airframe or component is designed to eperience in

    serice

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    Design 'ltimate oadoad %hich the structure must %ithstand %ithout collapse

    Safety *actor

    D'/D

    System "esign Philosophy

    Safe ife

    he structure is gien a life of hours and/or landings or

    pressuriation cycles and must )e remoed from serice %henthe appropriate criteria are met&

    he life is )ased on fatiue assessment and aircraft role& he

    fatigue life must )e recalculated if a change in aircraft role isproposed&

    Can a long haul airplane )e used for short sector flights on a long term)asis; 3o! hae to re assessShort term solution for shortage of aircraft; 6ossi)ly

    *ail Safe

    6hiliosophy anticipates a possi)le failure %ith minimum

    (f one component fails! the ad7acent components ta+e up the

    load for a limited period of time! usually until the net sericeinspection&

    Damage tolerant

    Does not hae specified life

    a+es structural %ea+ening into account

    oading spread oer larger area

    Damage can )e detected during the normal inspection cycles

    )efore a failure occurs

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    *atigue

    he life of an airframe is limited )y fatigue %hich is caused )y

    load cycles eperience during ta+eoff! landing and pressuriation&

    $ohler ,S/3- Cure leads to fatigue

    'se less load! more cycle

    he more the applied alternating stress! the lesser the num)er of

    cycles )efore it leads to fracture

    #oc$pit %indo%s

    oughened glass %ith inyl interlayers %ith ru))er sealing

    Coc+pit %indo% heating

    Conductie film applied to inner surfae of outer glass pane toproide electrical heating for anti

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    6assengers %indo%s ,6hoto-

    8ade of 6lastics ,6erspe-

    6assenger Door 6lug ype ,oc+ing 6ins-

    Cargo Door

    atch type/inge

    Pressure Bul$heads

    'npressurised areas: 3ose gear "ay! .ir Conditioning

    Compressor! 8ain Gear "ay! ail Cone

    ail S+id / ail stri+e might damage and depressurie tail cone

    *loor Venting ,"lo% out panels-

    Decompression in the cargo )ay leads ca)in pressure difference

    and ca)in floor might collapse! leading to actiation of the )lo%out )ungs

    Aluminium Alloy

    Duralmin

    .luminium and Copper Good Strength to $eight ratio

    6oor corrosion resistance

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    Good thermal and electrical conductiity

    6oor %elding capa)ility

    &ther metals

    Steel

    anding gear

    itanium

    ighter than steel

    Strong and high corrosion resistance

    Can %ithstand high temperatures

    'sed in high temperatures areas li+e engine compartment for fire

    protection

    8agnesium alloys 4cellent strength to %eight ratio

    6oor elastic properties

    3ot used in primary structures

    #omposites,in the form of laminate or sand%ich a+a honey& educe oerall airplane %eight

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    Disadantageous1& a+es time to cure

    ypical composite materials2& *i)erglass

    >& Car)on fi)er=& .ramide ,?elar-

    heir composition:

    8atri ,esin or *iller-%hich are )asically )inders

    *i)res %hich are reinforcements

    Anisotropic8eaning %e can tailor to the direction of the loadStiffness of composites depends on the panel design li+e the composition

    of the constituents&

    'sotropic.luminium or steel hae the uniform stiffness regardless of the directionof the load&

    Sand%ich structure composite

    %o thin )ut stiff s+in sheets and a light %eight )ut thic+ core

    he core! normally of lo% strength material! proides high )ending

    stiffness %ith oerall lo% density due to its thic+ness& (t also sta)ilies thecoering sheets&

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    'nsuita)le for a)sor)ing concentrated loads&

    uselage #onstruction

    hree types:

    russ Contruction! normally %ith fa)ric s+in @Diagonal )race and

    ongeronA

    8onocoue Constuction

    o S+in a)sor)s all the load

    o Cylindrical shape for maimum stiffness

    o *ormers or *rames are for shaping& (t does not support any

    load

    Semi

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    Wing construction #antile*er monoplane

    Wing construction - #omponents

    1& $ing sparsa& 8ain load )earing mem)ers of the %ing)& 8ain spar B thic+est section of the %ing

    2& i)s ,hae holes in them to lighten the %eight->& S+in

    a& *ormers that proide the %ing %ith cross sectional shape)& ae holes to reduce %eightc& ransfer some load from s+ins to the spar

    =& Stringer

    Torsion Bo+ or Bo+ SparSpurs )uilt into a )o shape %ith reinforced s+in forming the upper and

    lo%er sides of )o

    S$in

    8ore suited to a)sor)ing stress under tension than under

    compression %here )uc+ling tend to occur

    Stringers

    ong thin mem)er that runs the length of the %inf under the s+in

    .)sor) some of the )ending load

    elp stiffen the s+in against )uc+ling

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    ,mpennage

    Consists of ailplane and *in

    Similar to %ing construction

    Wing mounted engines *s Tail mounted ones ail mounted engines more prone to stall )ecause of the shift in

    CG

    $ing mounted engines more prone to ya% in case of single sided

    engine failure

    Probability of ailure #ondition and Se*erity ,(nsert 4.S.

    chart-

    Duple! riple

    ard Time Maintenance (different from Safe !ife. in specific toindi*idual component)

    ard ime maintenance is a primary maintenance process under

    %hich an item must )e remoed from serice at or )efore aspecified time for inspection or oerhaul

    .lso +no%n as ime "et%een #erhaul ,"#-

    &n #ondition Maintenance

    his is a preentie primary maintenance process %hich reuires

    that a component )e periodically inspected or chec+ed against

    some appropriate physical standard or limit to determine%hether it can continue in serice&

    (f the limit is eceeded! the part has to )e replaced

    (t is not a philosophy of fit and forget or fit until failure&

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    Pascal/s !a%

    6ressure E *orce / .rea

    *orce E 6ressure .rea

    $or+ Done E *orce Distance

    6o%er E $D / ime

    E *orce Distance / ime

    E 6ressure .rea Distance / ime

    E 6ressure Volume / ime

    8echanical .dantage

    he use of a small force to create a larger force else%here

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    ydraulics Applications

    "ra+es

    *laps

    anding Gear ,etracta)le-

    *light Controls "y conerting pressure energy into mechanical %or+s ,through

    actuators-

    $hy is hydraulics )etter than 6neumatics

    iuid is imcompressi)le

    iuid transmits pressue eually

    .ir can )e compressed )y 99&F5 of its oulume

    .ir is springy

    .is has time lag .ir B lea+s are difficult to detect

    .ir B not suita)le for heay loads

    3o return line needed in pneumatics ,adantage-

    ight %eight and no fire haard ,adantage-

    Summary

    ydraulics is used to conert pressure energy into mechanicalH

    ydraulics luid properties

    Good lu)rication

    o% iscosity

    $ide operating temperature range

    3on corrosie

    Sta)le

    3on toic

    igh flash point ,if-

    Types if hydraulic fluids 8ineral

    Synthetic

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    8ineral )ased ,D4* S.3 91

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    Acti*e 1 Passi*e ydraulics Systems

    .ctie system: 6ump reuired

    6assie System: 3o pump

    4am