aircra weight and balance - gavilan college -> faculty /...
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Aircra&WeightandBalance
Chapter4
WeightandBalanceChart
WeightandBalance• TheTCDS(TypeCer9ficateDataSheet)specifiestherangeofacceptableweightandcenterofgravity! Aircra&Specifica9onspre1958
• ThepilotmustinsurethattheairplaneisflownwithintherangesspecifiedbytheTCDS! Calcula9onsaremadewiththefuelattakeoffandatlanding.
• Thejobofthemechanicistomeasureanemptyaircra&andprovedthepilotwiththeaircra&’sweightandcenterofgravitybeforeanyloadisadded
WeightandBalance• WeightandBalanceelements
! Weight–theweightofanobject• Pilot• Passengers• Fuel• Baggage/Cargo• Theaircra&withnothinginit
! Calledtheaircra&’semptyweight
• MeasuredinlbsforUSAaircra&
! Arm–theloca9onofanobjectonthehorizontalaxis• MeasuredininchesforUSAaircra&
! Moment=WeightXArm
WeightandBalance• CenterofGravity(CG)–Thepointatwhichalltheobjectsareinbalance
• WeightandBalanceCalcula9ons! Findtheweightofeveryobject! Findthearmofeveryobject
! Findthemomentofeveryobject! Totalalltheweightstofindthetotalweight! Totalallthemomentsofeveryobjecttofindthetotalmoment
! FindtheCG=totalmoment/totalweight
WeightandBalance
Center of Gravity?
110”
Datum• Datum–thepointalongthehorizontalaxisthatservesasthereferencepointtomeasurearms
• SpecifiedintheTCDS• Usuallylocatedatthefirewalloratthenoseoftheaircra&
• Armsbehindthedatumareposi9ve
• Armsaheadorinfrontofthedatumarenega9ve! Example–Ifthedatumisatthefirewall,theenginearmwouldbenega9vebecauseitisaheadofthefirewall
WeightandBalance• FAA-H-8083-1Aircra&WeightandBalanceHandbook
• Emptyweight–theweightoftheairframe,engines,andallitemsofopera9ngequipmentthathavefixedloca9onsandarepermanentlyinstalledintheaircra&! Permanentballast! Oilandhydraulicfluids
• CAR(older)–nooil! Drainoilormathema9callysubtractoil
! Drainfueltounusableamount! Nodrinkingwaterorlavatoryprechargewater
WeightandBalance• Empty-weightCG–EWCG–CGatemptyweight• Maximumallowablegrossweight–themaximumweighttheaircra&canbe! DefinedinTCDS! Maybemorethanmaximumtakeofforlandingweight
! Ifyoufillalltheseats,fuelandbaggage;theaircra&willusuallybeovermaximumallowableweight
• Usefulload=Maximumallowablegrossweight–emptyweight! Fuel,passengersandbaggage
WeightandBalance• Zerofuelweight–Theweightofanaircra&withoutfuel! Thisisgivenbecausesomeaircra&requireaminimumnofuelload
• Leverarm-thedistancefromthefulcrumtoanobject
• Tareweight–theweightoftheequipmentusedinthemeasuringprocess(e.g.chocksandjacks)! Tareweightissubtractedbeforemakingcalcula9ons
StandardWeights• Avgas–6lb/USgal• JetA&A-1–6.8lb/USgal• JetB–6.5lb/USgal• Oil–7.5lb/USgal• Water–8.35lb/USgal
• AveragePassenger(perAC120-27E)! Summer(MaythruOct)–190lb! Winter(NovthruApr)–195lb! SomeFAAdocumentsuse170lb
Crea9ngWeightandBalanceInfo• Newaircra&aredeliveredwithweightandbalanceinforma9on
• Youmustverifythattheweightandbalanceinforma9oniscurrentateachannual! Ifnot,weightheaircra&
• Persec9on125.91(b),apart125opera9onmustreweightevery36months! Noperiodicrecheckrequirementforsmallaircra&
• A&eranaltera9on,theweightandbalanceinforma9onmustbeupdatedifthereismorethanan“negligible”amountofweightchange
Crea9ngWeightandBalanceInfo• Whatisgreaterthan“negligible”perAC120-27
! Large-cabinaircra&-+/-10lborgreater
! Medium-cabinaircra&-+/-5lborgreater! Small-cabinaircra&-+/-1lborgreater
• Determiningweightandbalanceinfoa&eranaltera9on! Weighttheaircra&! Doamathema9calcalcula9on
• Noneedtoreweighaircra&• Informa9onusuallycomesfromSTC
Crea9ngWeightandBalanceInfo• Themajorsourceofweightchangeformostaircra&astheyageiscausedbyrepairsandaltera9ons! Inreality,itisfromallthe“junk”le&intheaircra&bythepilotandrepairs
WeighinganAircra&• Cleanaircra&• Getdowntothe“requireequipmentlist”
! FromTCDS
! Consultall337sformodifica9onrequirements! Cleanthejunkout
• Securepermanentballasts(weights)andremovetemporaryballasts
WeighinganAircra&• Drainfuel
! Getdowntounusablefuel
! Ifunabletodrainfuel,filltanksandthenmathema9callysubtractfuel• Useanega9veweighofusablefuel
! (minus)usablefuelingallonsXweighoffuelpergallon(6lb/galforAvgas)
• FindthearmforthefuelintheTCDS
• Filloil! CARcer9fiedaircra&–drainoil(canusemath)
• Fillhydraulicfluids• Drainotherfluids
WeighinganAircra&• Moveaircra&toalevelspotwithnowind• Rollaircra&ontoscales
! Jackinganaircra&onascalecancauseerrorsbecausethelandinggearcompresseswhenlowered
! Releasebrakes
! Remembertousechockstopreventrolling
• Levelaircra&perTCDS! FAArecommendsusingaspiritlevel! Adjustpressureinnosegear
• Finddatumandtransfertothegroundusingaplumbbob
WeighinganAircra&• Transferlandinggearloca9onstotheground
! Useplumbbob
! Usethecenterofthewheelaxis
• Determinethelandinggeararmsbymeasuringthedifferencebetweenthedatumandthelandinggearloca9ons! Measurelongitudinalpor9ononly
• Notthedirectslantdistance• Remembertorecord(+)forbehindthedatumand(-)foraheadofthedatum
• Remembertosubtracttareweightfrommeasurements
WeightandBalancePrac9ce• WeightA–Weight100lb,armat0”• WeightB–Weight100lb,armat40”
• WeightC–Weight200lb,armat100”
WhatistheemptyweightandCG
Empty Weight is 400 lb with CG at 60” (Remember units)
WeightandBalancePrac9ce• WeightA–Weight100lb,armat-100”• WeightB–Weight100lb,armat40”
• WeightC–Weight200lb,armat10”
WhatistheemptyweightandCG
Empty Weight is 400 lb with CG at -10”
WeightandBalancePrac9ce• Nosewheel–Weight1,210lb,armat82.5”• Le&main–Weight2,510lb,armat197.5”
• Rightmain–Weight2,515lb,armat197.5”
WhatistheemptyweightandCG
Empty Weight is 6,235 lb with CG at 175.2”
WeightandBalancePrac9ce• Tailwheel–Weight50lb,armat120”• Le&main–Weight800lb,armat-11”
• Rightmain–Weight806lb,armat-11”
WhatistheemptyweightandCG
Empty Weight is 1,656 lb with CG at -7.0”
WeightandBalancePrac9ceAnaircra&withanemptyweightof1,500poundsandanemptyweightCGof+28.4wasalteredasfollows:1.two12-poundseatslocatedat+58.5wereremoved;
2.structuralmodifica9onsweighing+28poundsweremadeat+73;3.aseatandsafetybeltweighing40poundswereinstalledat+70.54.radioequipmentweighing35poundswasremovedat-8.5
5.Radioequipmentweighing15poundwasaddedat-8.5Whatisthenewemptyweight&CG?
Empty Weight is 1,524 lb with CG at 30.3”
WeightandBalancePrac9ceDatumisforwardofthemaingearcenterpointat30.24Actualdistancebetweentailgearandmaingearcenterpointsis360.26inchesNetweightatrightmaingearis8,100poundsNetweightatle&maingearis8,025pounds
Netweightattailgearis645poundsTheseitemswereintheaircra&whenweighed:
1.Lavatorywatertankfull(43poundsat+352).2.Hydraulicfluid(22poundsat-8).3.Removableballast(110poundsat+380).
Whatisthenewemptyweight&CG?
Empty Weight is 16,617 lb with CG at 41.1”
WeightandBalancePrac9ceDatumisforwardofthemaingearcenterpointat30.24Actualdistancebetweentailgearandmaingearcenterpointsis360.26inchesNetweightatrightmaingearis8,100poundsNetweightatle&maingearis8,025pounds
Netweightattailgearis645poundsTheseitemswereintheaircra&whenweighed:
1. Fullfuel(Avgas)–50galat50.5”(1.2galunusable)
Whatisthenewemptyweight&CG?
Empty Weight is 16,447.2 lb with CG at 44”
Adverse-LoadedCGChecks• Adverse-LoadedCGCheck–aweightandbalancecheckforextremecondi9ons
• FromFAA-H-8083-1A! IftheEWCG(EmptyWeightCenterofGravity)islocatedwithinthisrange,itisimpossibletolegallyloadtheaircra&sothatitsloadedCGwillfalloutsideofitsallowablerange.
! IftheTCDSlistanempty-weightCGrange,anda&erthealtera9oniscompleted,theEWCGfallswithinthisrange,thenthereisnoneedtocomputeaforeanda&checkforadverseloading.
Adverse-LoadedCGChecks• FromFAA-H-8083-1A
! ButiftheTCDSliststheEWCGrangeas“None”(andmostofthemdo),acheckmustbemadetodeterminewhetherornotitispossiblebyanycombina9onoflegalloadingtocausetheaircra&CGtomoveoutsideofeitheritsforwardora&limits.
FAAQues9on• When,orunderwhatcondi9on(s)areadverseloadingchecksconducted?! a.Atorbelowthemaximumgrossweightoftheaircra&.
! b.Any9mearepairoraltera9oncausesEWCGtofallwithintheEWCGrange.
! c.Atspecifiedflighthourorcalendar9meintervals.
FAAQues9on• When,orunderwhatcondi9on(s)areadverseloadingchecksconducted?! b.Any9mearepairoraltera9oncausesEWCGtofallwithintheEWCGrange.
FAAQues9on• IftheemptyweightCGofanairplanelieswithintheemptyweightCGlimits,! a.itisnecessarytocalculateCGextremes.! b.itisnotnecessarytocalculateCGextremes.! c.minimumfuelshouldbeusedinbothforwardandrearwardCGchecks.
FAAQues9on• IftheemptyweightCGofanairplanelieswithintheemptyweightCGlimits,! b.itisnotnecessarytocalculateCGextremes.
Adverse-LoadedCGChecks• Mustincludeminimums
! Pilot
! Minimumfuel
• Nominalpilotweightis170lb
• Minimumfuel-1/12gallonX“maximumexceptfortakeoffhorsepower”(METO)! SinceAvgasweights6lb/gallon
• 6lb/gX1/12gXMETO• 1/2lbXMETO
• METO/2lb
Adverse-LoadedCGChecks• ForwardAdverse-LoadedCGCheck
! Includeminimums
! EverypointinfrontoftheforwardCGlimitmustbefilledtothemaximum
• A&(back/rearward)Adverse-LoadedCGCheck! Includeminimums! Everypointbehindthea&CGlimitmustbefilledtothemaximum
• SeeFAA-8083-1Apages5-5&5-6
MeanAerodynamicChord(MAC)&CG• Usedforlargeaircra&• LEMAC–LeadingedgeoftheMAC
• TEMAC–TrailingedgeoftheMAC
• LEMACandTEMACarereferencetodatum
• CGin%MAC=CGfromLEMACX100/MAC! CGfromLEMAC=CG–LEMAC! Usethestandardweightandbalanceworksheetandthenconvertto%MAC
DeterminingNeededBallast• Aircra&isoutofCG,howdoyoucorrectit
! AddballastontheoppositesideoftheCG
• Ballastweight=(Aircra&weightXDistanceoutoflimits)÷(DistancebetweenballastanddesiredCG)! Distanceoutoflimits=ClosestCGlimit–CurrentCG
• Mustbeposi9ve
! DistancebetweenballastanddesiredCG=Whereyouareplacingtheballast–desiredCG• Mustbeposi9ve
• Ballastloca9onsareusuallypredefined
DeterminingNeededBallast• Aircra&weighs4,954lbwithCGat30.5”CGrangeis32.0”to42.1”Ballastcanbeplacedat162”
• Ballastweight=(Aircra&weightXDistanceoutoflimits)/(DistancebetweenballastanddesiredCG)! Distanceoutoflimits=32.0”–30.5”=1.5”! DesiredCG=Forwardlimit=32”
! DistancebetweenballastanddesiredCG=162”–32”=130”
! Ballastweight=(4,954lbX1.5”)/130”=! 57.16lb
POHInfo
POHInfo
CGmomentenvelopefromPilot’sOpera9ngHandbook.
WeightandBalancePrac9ceA&eraltera9on,anN123ABPA-28-160S/N28-1650wasweighedwithfullfuelandoil1. Nosewheel–400lb@31”
2. Le&main–[email protected]”3. Rightmain–[email protected]”
Whatisthenewemptyweight&CG?Hint1:FullfuelandunusablefuelhavedifferentCG
Hint2:Whataboutoil?Hint3:Themomentstotal=96679.6Hint4:7itemslistedinworksheet
Empty Weight is 1,119 lb with CG at 86.4”