68831900 Module 07 B1 Mechanical Book 1

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MAINTENANCE PRACTICES(mechanical

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CONTENTS

1 INTRODUCTION################################################################################1$ SA%ETY PRECAUTIONS##################################################################1

$#1 %i&e###################################################################################################12.1.1 The Fire Triangle...............................................................22.1.2 Classes of Fire....................................................................22.1.3 Fire Extinguishants and their Uses.....................................3

$#$ %i&' Ai)###########################################################################################*

$#+ ,-&"'h-. an) /an0a& Sae2########################################################*2.3.1 Machinery...........................................................................52.3.2 Electricity............................................................................

2.3.3 !oise.................................................................................."2.3.# $igh%&ressure 'ases........................................................."2.3.5 'as (ottle )dentification......................................................*2.3. $igh%&ressure 'as +e,lenishing........................................*2.3." -xygen yste/s................................................................02.3.* iation -ils and Fuels.......................................................12.3.0 Che/ical and &hysiological $a4ards..................................112.3.1 ifting and horing............................................................112.3.11 linging.............................................................................12

$#3 %li0h4Line Sae2###########################################################################1+2.#.1 To6ing and Taxying...........................................................1#2.#.2 &ar7ing...............................................................................15

2.#.3 Marshalling.........................................................................12.#.# Fuelling...............................................................................1"2.#.5 8eather +adar...................................................................1*

+ ,OR5S/OP PRACTICES################################################################1

+#1 Ca&e - T--l'###################################################################################1

+#$ C-n&-l - T--l'##############################################################################$

+#+ Cali&ai-n - T--l' an) E!i.men##############################################+3.3.1 'eneral !otes on Cali9ration.............................................33.3.2 &rocedures.........................................................................#

+#3 U'e - ,-&"'h-. Mae&ial'############################################################6

+#* San)a&)' - ,-&"man'hi.###########################################################73 TOOLS################################################################################################1

3#1 C-mm-n /an) T--l'######################################################################1#.1.1 Engineers +ule..................................................................1#.1.2 cri9er................................................................................2#.1.3 :ey%eat +ule....................................................................2#.1.# Fitters ;uare....................................................................3#.1.5 Co/9ination et.................................................................##.1. urface &lates and Ta9les..................................................5#.1." < (loc7s.............................................................................5#.1.* urface 'auge =cri9ing (loc7>..........................................#.1.0 ?iiders.............................................................................."

#.1.1 Calli,ers..........................................................................."#.1.11 $a//ers..........................................................................*

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#.1.12 &unches...........................................................................0#.1.13 Metal%Cutting Chisels........................................................1

#.1.1# (ench


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5.2.3 ectional


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7#$ T2.e' - Ri@ee) J-in'##################################################################3

7#+ Cl-'in0 S-li) Ri@e'#######################################################################3

7#3 Cl-'in0 /-ll-8 Ri@e'###################################################################*".#.1 Tuc7er%,o,.........................................................................5".#.2 Cho9ert...............................................................................5".#.3 del..................................................................................".#.# Cherry Max........................................................................."".#.5 $i%o7.................................................................................*".#. +inuts...............................................................................*

7#* In'.eci-n - Ri@ee) J-in'##########################################################=

7#6 Ri@e Rem-@al P&-ce)!&e###############################################################1;

PIPES AND /OSES###########################################################################1

#1 Pi.e Ben)in0###################################################################################1

*.1.1 i/,le (ending igs...........................................................2*.1.2 $and &i,e%(ending Machines............................................2

#$ Pi.e %la&in0#####################################################################################+*.2.1 Flaring Tool........................................................................3*.2.2 tandard Flared &i,e Cou,lings.........................................#*.2.3 Flareless Cou,lings............................................................5

#+ In'.eci-n an) Te'in0 - Pi.e' an) /-'e'#################################6*.3.1 (ore Testing of &i,es........................................................."*.3.2 $ydraulic &ressure Testing of &i,es..................................."*.3.3 &neu/atic and -xygen &ressure Testing of &i,es............."*.3.# Cleaning fter Test............................................................."

*.3.5 Testing Flexi9le $oses.......................................................*#3 In'allai-n an) Clam.in0 - Pi.e'################################################

*.#.1 &i,e u,,orts.....................................................................*

#* C-nneci-n - Pi.e'#######################################################################1;

#6 Mainenance - Pi.e' an) /-'e'##################################################1;

#7 Pi.e I)eniicai-n Ta.e##################################################################11

= SPRINGS############################################################################################1

=#1 In'.eci-n an) Te'in0 - S.&in0'################################################1

1; BEARINGS#######################################################################################1

1;#1 Cleanin0 an) In'.eci-n - Bea&in0'##########################################1

1;#$ In'.eci-n - Bea&in0'#################################################################$1.2.1 !or/al Fatigue.................................................................21.2.2 Excessie oads...............................................................21.2.3 )nstallation and Misalign/ent...........................................31.2.# oose Fit...........................................................................31.2.5 (rinelling...........................................................................31.2. -erheating and u9rication Failure.................................#1.2." Conta/ination and Corrosion...........................................5

1;#+ Sae2 P&eca!i-n'########################################################################*

1;#3 S-&a0e##########################################################################################*

11 TRANSMISSIONS############################################################################1

11#1 Gea&'##############################################################################################1

11#$ Bel' an) P!lle2'##########################################################################1

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11#+ Chain' an) S.&-c"e'##################################################################$

11#3 Sc&e8 Jac"'##################################################################################+

11#* Le@e&'############################################################################################311.5.1 &ush%&ull +od yste/s....................................................5

1$ CONTROL CABLES########################################################################1

1$#1 S8a0in0 - En) %iin0'###############################################################1

1$#$ In'.eci-n an) Te'in0 - C-n&-l Cale'##################################112.2.1 Ca9le 8ear.......................................................................112.2.2 (o6den and Teleflex Ca9le yste/s...............................3

1$#+ In'.eci-n - C-n&-l Cale P!lle2'############################################3

1+ S/EET METAL ,OR5####################################################################1

1+#1 Ma&"in0 O!###################################################################################$

1+#$ %-&min0 - Shee Meal Pa&'#######################################################+13.2.1 Cutting..............................................................................313.2.2 (ending and Calculation of (end llo6ance....................#

1+#+ In'.eci-n - Shee Meal ,-&"###################################################

13 ,ELDING9 SOLDERING AND BONDING######################################1

13#1 ,el)in0##########################################################################################1

13#$ Meh-)' - ,el)in0######################################################################11#.2.1 -xy%cetylene Fla/e.......................................................11#.2.2 Manual Metal rc..............................................................21#.2.3 Metal rc 'as%hielded =M'>......................................21#.2.# Tungsten rc 'as%hielded =T'> ................................2

1#.2.5 Flash (utt 8elding...........................................................31#.2. ,ot 8elding....................................................................31#.2." ea/ 8elding..................................................................3

13#+ In'.eci-n an) Te'in0 - ,el)'#################################################+

13#3 S-l)e&in0#######################################################################################3

13#* Meh-)' - S-l)e&in0###################################################################31#.5.1 $ard oldering =(ra4ing and iler oldering>.................#1#.5.2 oft oldering...................................................................51#.5.3 Using )ndirectly $eated =Electric> oldering )rons.............1#.5.# ctie and &assie Fluxes................................................*1#.5.5 Flux +e/oal....................................................................1

13#6 In'.eci-n an) Te'in0 - S-l)e&e) J-in'#################################1;13#7 B-n)in0#########################################################################################1;

13# Meh-)' - B-n)in0#####################################################################111#.*.1 Ther/o,lastic dhesies..................................................111#.*.2 Ther/osetting dhesies.................................................12

13#= In'.eci-n an) Te'in0 - B-n)e) J-in'###################################1$

1* AIRCRA%T MASS AND BALANCE################################################1

1*#1 Deinii-n'#####################################################################################1

1*#$ Ma'' an) Balance#########################################################################$15.2.1 Mass and (alance ?ocu/entation...................................3

1*#+ %&e!enc2 - ,ei0hin0################################################################315.3.1 Fleet Mass and C' &osition.............................................#



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1*#3 ,ei0hin0 Re!i&emen'###############################################################3

1*#* Cen&e - G&a@i2 Limi' (CG [email protected]######################################*

1*#6 Rec-&)'#########################################################################################*

1*#7 Calc!lai-n - Ma'' an) CG - an2 S2'em################################*

1*# P&inci.le' - ,ei0h an) Balance - Ai&c&a##############################7

1*#= Calc!lai-n - Ma'' an) CG - Ai&c&a#######################################7

1*#1; Ai&c&a ,ei0hin0 Meh-)'#########################################################15.1.1 &re,aration for 8eighing................................................015.1.2 8eighing on ircraft ac7s.............................................015.1.3 Calculation of ircrafts C'.............................................115.1.# C' as &ercentage tandard Mean Chord =MC>...........12

1*#11 Chan0e' in Ba'ic ,ei0h###########################################################1$

15.11.1 Exa/,les of lterations to ?ry -,erating Mass..............131*#1$ L-a)in0 - Ai&c&a (T2.ical Ai&c&a L-a) Shee#####################1*

16 AIRCRA%T /ANDLING AND STORAGE#######################################1

16#1 M-@in0 Meh-)' ###########################################################################$1.1.1 Moing 9y $and and teering r/...................................21.1.2 Using a (ridle and teering r/.......................................21.1.3 Using a &ur,ose%Made To6ing r/.................................31.1.# &recautions 6hen To6ing ircraft....................................31.1.5 Taxiing ircraft..................................................................#

16#$ Ai&c&a Jac"in0#############################################################################*1.2.1 ,ecial Considerations.....................................................5

1.2.2 ircraft ac7s....................................................................1.2.3 ac7 Maintenance and 'eneral !otes.............................."1.2.# ac7ing &recautions.........................................................*1.2.5 ac7ing &rocedures..........................................................*1.2. Trestles.............................................................................01.2." o6ering ircraft off ac7s................................................1

16#+ Slin0in0 #########################################################################################1;1.3.1 ifting Tac7le....................................................................11

16#3 Pa&"in0 an) M--&in0 Ai&c&a#######################################################1$1.#.1 &ar7ing.............................................................................121.#.2 Mooring =&ic7eting>...........................................................131.#.3 Ty,ical /all ircraft &rocedures.....................................1#1.#.# arge ircraft &rocedures.................................................1#1.#.5 Choc7ing of ircraft..........................................................15

16#* Ai&c&a S-&a0e#############################################################################16

16#6 Ai&c&a %!ellin0 P&-ce)!&e'########################################################$;1..1 Fuelling afety &recautions .............................................21..2 +efuelling.........................................................................211..3 Chec7ing Fuel Contents...................................................211..# ?efuelling.........................................................................22

16#7 G&-!n) De4Icin0Ani4Icin0 - Ai&c&a#########################################$+1.".1 )ce Ty,es..........................................................................231.".2 ?efinitions.........................................................................251.".3 ?e%)cing and nti%)cing Methods.......................................251.".# Che/ical ?e%)cing............................................................2

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1".3. cid ,illage.....................................................................11".3." l7ali ,illage...................................................................1

1".3.* Mercury ,illage...............................................................1"17#3 Pe&manen Ani4C-&&-'i-n T&eamen'#######################################1

1".#.1 Electro%&lating..................................................................1*1".#.2 ,rayed Metal Coatings...................................................1*1".#.3 Cladding...........................................................................1*1".#.# urface Conersion Coatings...........................................10

17#* N-n4De'&!ci@e Te'in0In'.eci-n (NDTNDI Techni!e'#####$;1".5.1 ...............................#1".5. Magnetic &article Fla6 ?etection =M&F?>........................#"1".5." +adiogra,hic Fla6 ?etection =+F?>.................................531".5.* Miscellaneous +adiation Techni;ues ..............................50

17#6 Di'a''eml2 an) Re4a''eml2 Techni!e'###############################6;1"..1 Co/,lete irfra/es..........................................................1"..2 +e,lace/ent of MaBor Co/,onentsAModules...................11"..3 +e,lace/ent of Minor Co/,onentsAModules...................21"..# ?isasse/9ly and +e%asse/9ly of MaBor Co/,onents......21"..5 ?isasse/9ly and +e%asse/9ly of Minor Co/,onents......21".. (asic ?isasse/9ly and +e%asse/9ly Techni;ues............31".." /all &art and Co/,onent )dentification..........................#

1"..* ?iscarding of &arts...........................................................51"..0 Freeing ei4ed Co/,onents............................................51"..1 Use of Correct Tools.......................................................51"..11 Mur,hys a6................................................................

1 ABNORMAL E?ENTS#####################################################################1

1#1 T2.e' - an-&mal -cc!&&ence'##################################################1

1#$ T2.e' - )ama0e###########################################################################1

1#+ Li0hnin0 S&i"e' ##########################################################################$1*.3.1 Effects of a ightning tri7e..............................................21*.3.2 )ns,ection.........................................................................2

1#3 E


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1*..1 Exa/,le of &ost $eay anding )ns,ection......................12

1#7 %li0h h&-!0h Se@e&e T!&!lence###############################################13

1= MAINTENANCE PROCEDURES#####################################################11=#1 Mainenance Plannin0##################################################################1

1=#$ M-)iicai-n P&-ce)!&e'##############################################################$10.2.1 MaBor Modifications...........................................................210.2.2 Minor Modifications...........................................................2

1=#+ S-&e' P&-ce)!&e'########################################################################+

1=#3 Ce&iicai-n an) Relea'e P&-ce)!&e'#########################################+10.#.1 )nterface 6ith ircraft -,eration.......................................#

1=#* Mainenance In'.eci-n !ali2 C-n&-l an) A''!&ance#### ## #*

1=#6 A))ii-nal Mainenance P&-ce)!&e'###########################################6

1=#7 C-n&-l - Lie4Limie) C-m.-nen'###########################################6



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1 INTRODUCTION

Most accidents are@ in the /ain@ caused 9y hu/an carelessness and accidents inthe 6or7 ,lace are a/ong the /ain causes of death and disa9ility.

They are@ additionally@ the cause of a great loss of /an%hours and@ thus@ costco/,anies =and indiiduals> large a/ounts of /oney.

ll ,ersonnel should 9e a6are@ not only of the ,otential for accidents and inBury@6hereer they 6or7@ 9ut also of the legislation and infor/ation that is aaila9le inan atte/,t to ,reent accidents actually ha,,ening.

8hile it is incu/9ent u,on co/,anies =in accordance 6ith The Manage/ent of$ealth and afety at 8or7 +egulations 1002>@ to ensure that all ,ersonnelreceie ade;uate training in $ealth and afety /atters@ this Module contains are/inder of so/e of the general safety ,recautions 6hich are necessary@ 6hen6or7ing in the aeros,ace industry.

The Module continues 6ith further to,ics@ 6hich are concerned 6ith the ,racticesreco//ended for the safe and efficient /aintenance of aircraft and aeros,aceco/,onents.



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$ SA%ETY PRECAUTIONS

ircraft@ 9y their ery nature and design@ /a7e for a dangerous 6or7ingeniron/ent. The danger is further increased 9y the 6ide ariety of /achines@tools and /aterials re;uired to su,,ort and /aintain aircraft.

&ersonal safety starts 6ith 9eing a,,ro,riately dressed for the 6or7 9eingunderta7en@ co/9ined 6ith the correct use of eye and ear ,rotection 6heneernecessary.

Technicians should only o,erate e;ui,/ent 6ith 6hich they are fa/iliar and6hich they can o,erate safely. $and tools should 9e 7e,t in good 6or7ing order.

'ood house7ee,ing in 6or7sho,s@ hangars@ and on flight line ra/,s is essentialto safe and efficient /aintenance.

&edestrian and fire lanes should 9e clearly /ar7ed and !E@ and of the ,rocedures to 9e follo6ed in anye/ergency.

$#1 %i&e

8+!)!' 8 E!U+E T$T C-++ECT F)+E &+ECUT)-! +E-(EE? !? T$T EC&E +-UTE +E !-T -(T+UCTE?. ET$FUME !? M-:E C! (E &+-?UCE? ( CE+T)! MTE+) !?

T$E C! (U+!


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2.1.3Fire Extinguishants and their Uses

The /ethods of extinguishing fires hae led to the deelo,/ent of seeral ty,esof extinguishants to cater for different ty,es of fire. These /ethods include

Cooling the fuel

Excluding the oxygen

e,arating the fuel fro/ the oxygen

The /aterials@ used as general do/estic and co//ercial extinguishants@ differfro/ those used in aircraft Fire &rotection syste/s and@ 6hile the aircraft syste/sare discussed in other Modules of this course@ consideration is gien here only tothe extinguishants and extinguishers 6hich confor/ to the E!3 tandard fireextinguisher code. The /aterials used in these extinguishers are

8ater =8aterA'as>

;ueous Fil/%For/ing Foa/ =FFF>

Car9on ?ioxide =C-2>

?ry &o6der

,,lying the incorrect extinguishant to a fire can do /ore har/ than good and/ay@ actually@ 9e dangerous. )t is@ therefore@ i/,ortant that extinguishers are 6ell/ar7ed for ;uic7 identification in an e/ergency. )t is also ital that all ,ersonnel

are a6are of the /ar7ings@ 6hich a,,ear on extinguishers@ so that the correct oneis chosen to deal 6ith a s,ecific fire.

Ta9le 2 sho6s ho6 the E!3 tandard fire extinguisher code has re,laced theolder tandard@ 6here9y the extinguisher containers 6ere colour%coded all oerto signify their contents. The E!3 tandard has the 9odies of eery fireextinguisher coloured red all oer@ 6ith an identifying 9and of colour@ se,arated9y 6hite lines@ identifying the extinguishant contained in the extinguisher.

Ta9le 2F)+E EGT)!'U)$E+ )?E!T)F)CT)-! !? UE

E!3 tandard Extinguishers =ll%red Container>Extinguishant (and Colour Ty,es of Fire

8ater=8aterA'as>

+ed olids only@ 9ut !-T Electrical !-+Fla//a9le i;uids

;ueous Fil/%For/ing Foa/=FFF>

Crea/ -il@ Fats@ &aint@ &etrol@ and olids@9ut !-T safe on Electrical fires

Car9on ?ioxide=C-2>

(lac7 'ases@ Electrical@ Fla//a9le i;uidsand olids 9ut !-T (urning Metals

?ry &o6der (lue (urning Metals@ Fla//a9le i;uids@and Electrical =H1 fires



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Fro/ Ta9le 2 it can 9e seen that 8ater or 8aterA'as extinguishers are -! to9e used on fires inoling 9urning solids =Class fires>. 8ater could also cause

li;uid fires to s,read and@ o9iously@ using 6ater on electrical e;ui,/ent couldhae lethal results@ so these extinguishers /ust !-T 9e used on Class ( !-+on Class C fires. 8ater should@ also@ !-T 9e used on 9urning /etal =Class ?>fires@ as the oxygen@ in the 6ater@ 6ill cause the fires to 9urn /ore fiercely and itsuse could lead to iolent ex,losions.;ueous Fil/%For/ing Foa/ =FFF> is 9est suited for Class ( fires@ due to itss/othering and cooling action and to the fact that its finer ,articles 6ill not causethe fire to s,read. FFF extinguishers can also 9e used on Class fires =thoughits cooling action is not as effectie as the 6ater extinguishers>@ 9ut@ 9ecauseFoa/ does contain 6ater@ FFF extinguishers are considered to 9e !-T safe on

electrical fires 6here high oltages are encountered.

Car9on ?ioxide =C-2> is the uniersal fire extinguisher and@ 9eing non%corrosie@non%conductie@ and leaing no residue@ it is suita9le for al/ost all ty,es of fire.C-2extinguishers /ust !-T@ ho6eer@ 9e used on Class ? fires@ as theextinguishant reduces the te/,erature ery ;uic7ly@ 6hich =in a si/ilar 6ay to theuse of 6ater extinguishers> could cause serious ex,losions.

?ue to the fact that C-2gas tends to dissi,ate ;uic7ly@ the extinguisher is,roided 6ith a horn deice@ 6hich hel,s to concentrate the C-2at the site of thefire. This horn /ust !-T 9e held 6ith 9are hands@ as the intense cold of thereleased C-26ill free4e the s7in to the horn@ resulting in seere inBury to thehands. ru99er@ insulated coating is ,roided on the discharge tu9e and the C-2/ust 9e directed to6ards the fire 9y gras,ing and /ani,ulating the insulatedtu9e.

?ry &o6der is another extinguishant 6hich is suita9le for /ost classes of fire@and@ in ,articular@ those inoling 9urning /etals =aircraft 6heel 9ra7e fires>. )t is@ho6eer@ li/ited in its use on electrical fires@ as the ,o6der ,articles are ca,a9leof conducting high oltages =in excess of 1 and@ ,ossi9ly@ lesser oltages ifthey are used at distances of less than 1 /etre fro/ electrical fires. ?ry &o6der

=in a si/ilar 6ay to Foa/>@ leaes a /essy residue after its use@ 6hich could,resent a ,ro9le/ to electrical contacts and circuitry.

!ote )t is ,ossi9le that the older tandard $alon fire extinguishants =in green%coloured containers> /ay 9e found at /any indoor locations. Unfortunately@ 6hile$alons =$alogenated $ydrocar9ons> are extre/ely effectie as extinguishants ofirtually eery class of fire@ it is felt that they contri9ute to the de,letion of theo4one layer surrounding Earth and@ so@ they are 9eing ,hased out of use.

(uc7ets of dry sand /ay also 9e ,laced at the F)+E &-)!T in 6or7sho,s =andes,ecially in hangars> as an additional aid to fire fighting.



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$#$ %i&' Ai)

)t has 9een ,reiously discussed that@ 6hen 6or7ing indoors@ 6hether it is in anoffice@ a 6or7sho, or a hangar@ there 6ill 9e fixed ,oints 6here fire%fightinge;ui,/ent is aaila9le. i/ilarly@ there 6ill 9e First id ,oints 6here e/ergency7its@ eye 6ashing e;ui,/ent and call 9ells are installed and there 6ill 9e trainedFirst id ,ersonnel to assist in the treat/ent of inBuries. )t is the res,onsi9ility ofeery ,erson at 6or7 to 7no6

The location of the First id &oints The /ethods of calling for hel, The locations of alar/ 9ells@ and the siting of a,,ro,riate tele,hones 6hich

/ay 9e used to su//on hel, in an e/ergency The identity of the trained First id ,ersonnel in their icinity

)n the eent of an inBury =ho6eer slight>@ it is i/,ortant that the inBured ,erson@ orthe attending First ider@ should co/,lete an entry in the ccident (oo7@ 6hich isusually 7e,t near the First id &oint.

$#+ ,-&"'h-. an) /an0a& Sae2

8hen 6or7ing in a 6or7sho, or in any hangar@ there are a nu/9er of safety,recautions that /ust 9e follo6ed@ if inBury =or death> is to 9e aoided.

2.3.1Machinery

/achine can 9e defined as an a,,aratus for a,,lying ,o6er@ haing fixed and/oing ,arts@ each haing a definite function. )n ,articular@ /achines e/9race

-,erational &arts % ,erfor/ing the ,rinci,al out,ut function =Chuc7s or (its> !on%-,erational &arts % coneying ,o6er or /otion =Motor ?ries>.

The 6ide range of /achinery@ aaila9le in 6or7sho,s and hangars@ ,recludesgiing s,ecific rules and regulations for each /achine. The 9asic drilling@ grinding

and /illing ty,es of /achine@ all re;uire the use of eye ,rotection@ attach/ent ofguards@ secure holding of 6or7 and@ /ost i/,ortantly@ correct training 9efore9eing o,erated.

&ossi9le accidents fro/ /achinery@ in general@ include ,ersonnel

Co/ing into contact 6ith the /achinery (eing tra,,ed 9et6een /achinery and /aterial (eing struc7 9y /achinery or 9eing entangled in its /otion (eing struc7 9y eBected ,arts or /aterial +eceiing electric shoc7s fro/ the /achinery



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2.3.2Electricity

The hu/an 9ody conducts electricity. Further/ore@ electrical current@ ,assingthrough the 9ody@ disru,ts the nerous syste/ and causes 9urns at the entry andexit ,oints. The current@ used in do/estic 22%2# olt@ 5$4 ac electricity@ is,articularly dangerous 9ecause it affects neres in such a 6ay that a ,erson@holding a current%carrying conductor@ is una9le to release it. Ta9le 2 sho6s so/ety,ical har/ful alues and effects of 9oth ac and dc electricity su,,lies.

Ta9le 2$+MFU


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hout for hel, and ensure there is no danger of also 9eco/ing a icti/

6itch off the electrical current or re/oe the icti/ fro/ the su,,ly 9y /eans

of insulated /aterial )f the icti/ has ceased 9reathing@ initiate resuscitation

Call for ,rofessional /edical hel,

)f the icti/ is suffering fro/ 9urns@ exclude air fro/ 6ounds

Treat for shoc7 9y 7ee,ing the icti/ 6ar/

The a,,roed /ethods of artificial resuscitation /ust@ 9y la6@ 9e dis,layed on6all charts in 6or7,laces.

2.3.3!oise

8or7sho,s@ hangars and flight lines can 9e ery noisy ,laces of 6or7@ so it isessential that ear defenders@ or so/e other ,rotection such as ear ,lugs@ areused at all ti/es that noise is ,erceied to 9e a ris7. oss of hearing@ leading todeafness@ can 9e the result of o,erating in a noisy eniron/ent 6ithout ade;uateear ,rotection. Ear ,rotection is o,tional 6here noise leels are less than *5 d(@9ut is /andatory 6hen greater than 0 d(.

2.3.#$igh%&ressure 'ases

Co/,ressed gases are fre;uently used in the /aintenance and sericing of

aircraft. The use of co/,ressed gases re;uires a s,ecial set of safety /easures.The follo6ing rules a,,ly for the use of co/,ressed gases

Cylinders of co/,ressed gas /ust 9e handled in the sa/e 6ay as any high%energy =and therefore ,otentially ex,losie> sources

Eye ,rotection /ust al6ays 9e 6orn 6hen handling co/,ressed gases

!eer use a cylinder that cannot 9e ,ositiely identified

8hen storing or /oing a cylinder@ hae the ca, securely in ,lace to ,rotectthe ale ste/

8hen large cylinders are /oed@ ensure that they are securely attached to

the correct trolley or ehicle Use the a,,ro,riate regulator on each gas cylinder

!eer direct high%,ressure gases at a ,erson

?o not use co/,ressed gas or co/,ressed air to 9lo6 a6ay dust and dirt@ asthe resulting flying ,articles are dangerous

+elease co/,ressed gas slo6ly. The ra,id release of a co/,ressed gas 6illcause an unsecured gas hose to 6hi, a9out and een 9uild u, a staticcharge@ 6hich could ignite a co/9usti9le gas

:ee, gas cylinders clean. -il or grease on an oxygen cylinder can causes,ontaneous co/9ustion and ex,losions

"1*111"5.doc )ssued ?ece/9er 22 &age "


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2.3.5'as (ottle )dentification

$igh%,ressure gas cylinders contain arious ty,es of gas@ the /ost co//on usedon co//ercial aircraft 9eing nitrogen and oxygen. To ensure correct identificationof these containers@ they are colour coded and the na/e of the gas is stencilledon the side.

)n the U:@ gas containers use ( 3*1C as the standard to deter/ine the correctcolour and shade for each gas ty,e. !itrogen 9ottles are ,ainted grey on the9ody 6ith a 9lac7 nec7@ 6hilst oxygen 9ottles are 9lac7 6ith a 6hite nec7. (ea6are that 9ottles of U /anufacture use an alternatie syste/@ the /aindifference 9eing oxygen 9ottles are ,ainted green all oer.

2.3.$igh%&ressure 'as +e,lenishing

8hen re,lenishing aircraft serices such as tyres and hydraulic accu/ulators6ith high%,ressure gas@ care /ust 9e ta7en to ensure that only the re;uired,ressure enters the container. 8hen full@ a gas storage 9ottle can hold as /uchas 2 9ar =3 ,si> 6hilst an aircraft tyre ,ressure /ay only re;uire " 9ar =1,si>.

To safely control the gas@ t6o ,ressure regulating ales are used@ one at thestorage 9ottle end and one at the deliery end of the syste/. )f one ale fails theother 6ill ,reent the receiing essel fro/ ta7ing the full 9ottle ,ressure 6ith theconse;uence of an ex,losion.

For added safety the gas 9ottle ale o,ening 7ey should 9e left in the ale6hilst decanting o,erations are co/,leted. )f ,ro9le/s occur then the high%,ressure 9ottle can 9e ;uic7ly isolated 9efore the situation 9eco/es dangerous.

The transfer of high%,ressure gases fro/ a large storage 9ottle to the aircraftco/,onent is often called decanting and /ust 9e done at a ery slo6 rate. )f thegas is decanted ra,idly the te/,erature of the receiing co/,onent 6ill increasein accordance 6ith the gas la6s.

gain using the sa/e gas la6s the te/,erature of the gas in the container 6illdro, to a/9ient@ and the ,ressure in that essel 6ill reduce. The co/,onent,ressure 6ill no6 9e incorrect and re;uire the decanting ,rocess to 9e re,eated.

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8hen Bac7ing an aircraft asy//etrically@ there is usually so/e /oe/ent 9y theother legs. Care /ust 9e sho6n@ 6hen Bac7ing a single leg@ that the aircraft is

raised strictly in accordance 6ith the /aintenance /anual.

-ther ,laces 6here a larger Bac7 /ay 9e connected to the airfra/e /ight 9e

Under the 6ings@ at the /ain s,ar ,osition Under the nose Under the tail asse/9ly -n the side of the front fuselage =in ,lace of the nose Bac7>

The location and o,eration of Bac7s /ust 9e carried out 9oth 6ith great careand 6ith the correct nu/9er of ,ersonnel@ 6ho /ust 9e 6ell 9riefed.

Most of the larger Bac7s hae a scre6%ty,e@ safety loc7ing collar@ to ,reent theBac7 colla,sing in the eent of a sudden lea7. The Bac7 o,erator /ust ensure thatthese safety collars are gradually scre6ed do6n@ as the aircraft is 9eing raised@so that they are ery close to the Bac7 9ody at all ti/es.

s an additional ,recaution@ es,ecially if the aircraft is to 9e 6or7ed on for anextended ,eriod@ trestles or steadies can 9e installed under the 6ings andfuselage to aug/ent the Bac7s and also to ,roide an additional /eans of shoring=su,,orting> the aircraft.

2.3.11 linging

)t can 9e necessary@ on occasions@ to lift either the /aBor co/,onents of anaircraft@ such as 6ing or tail asse/9lies or the co/,lete aircraft =refer to Fig. 2>.For exa/,le@ 6hen recoering an aircraft fro/ an oerrun@ it /ay 9e easier@ andsafer@ to lift the entire aircraft and ,lace it onto a hard standing@ than to try and,ull it out of soft ground@ using a tug or si/ilar ehicle.

8hen lifting either /aBor co/,onents or an entire aircraft@ the slings /ust 9e,roduced or a,,roed 9y the /anufacturer of the aircraft. The /anufacturers

slings ensure that the centre of graity of the co/,onent@ is al6ays directly9eneath the lifting hoo7 of the sling.



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$#3 %li0h4Line Sae2

Many sources of accidents on the flight line are inoled 6ith ,ro,ellers and rotor9lades. They are difficult to see 6hen they are turning@ and ,ersonnel =des,ite9eing fa/iliar 6ith the ha4ards of ,ro,ellers and rotors>@ so/eti/es 9eco/edistracted and forget a9out the danger. The /ain difference 9et6een these@ andother flight%line accidents@ is that they are al/ost al6ays fatal.

Most 9lades hae high%isi9ility /ar7ings@ to ensure that they can 9e seen 6henthey are turning. These /ar7ings ary fro/ a yello6 9lade ti, /ar7ing@ to 9lac7and 6hite alternate stri,es along the full 9lade length.

To reduce the ris7 of ,ro,eller and rotor 9lade stri7es@ it is 9est to follo6 strictrules as to the correct 6ay to a,,roach and leae the icinity of an aircraft or

helico,ter 6hilst it is under ,o6er. For exa/,le =and allo6ing for the fact thatthere are s,ecific rules laid do6n for each aircraft>@ installing and re/oingchoc7s should nor/ally 9e done fro/ the 6ing%ti, direction. (oarding and leainga helico,ter should al6ays 9e done fro/ the side.

8hen dealing 6ith running Bet engines there are si/ilar dangers. These co/e notonly fro/ the noise ris7@ 6hich can result in deafness@ 9ut also fro/ the ris7 ofinta7e suction@ 6hich has resulted in ra/, ,ersonnel 9eing suc7ed into theengine and 9eing 7illed. t the rear of the aircraft@ there is the ris7 of Bet 9last@6hich@ at /axi/u/ thrust is ;uite ca,a9le of oerturning a ehicle if it ,asses tooclose 9ehind the aircraft. =refer to Fig. 3>. &iston%,o6ered aircraft =de,ending on

their si4e> 6ill hae si/ilar danger areas.


ifting an ircraft 6ith lingsFig. 2


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2.#.2&ar7ing

8hen an aircraft has to 9e ,ar7ed for a ,eriod of ti/e@ es,ecially oernight and inincle/ent 6eather conditions@ there are a nu/9er of ,recautions that /ust 9eo9sered

choc7 /ust 9e ,laced at the front and rear of a nu/9er of 6heels@

de,ending on the aircraft ty,e The engine inta7es and exhausts /ay need to 9e coered 6ith s,ecial 9lan7s

The control surfaces /ay hae to 9e loc7ed in ,lace 6ith integral control orgust loc7s or@ if these are not installed@ external loc7s /ay 9e attached to all ofthe surfaces that could 9e da/aged in high 6inds

-ther deices re;uired could include 9lan7s for the ,itot tu9es and staticents.


8ing Ti, 6ee, reaTail 6ee, rea

&ath of 8ing Ti, &ath of Tail

ircraftTurningTo eft

6e,t 8ing 'ro6thFig. #


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2.#.3Marshalling

8hen /arshalling an aircraft@ it is essential that ,ersonnel are fully conersant6ith all the /arshalling signals =refer to Fig. 5>. )t is also useful to 7no6 extradetails such as

The need for additional@ loo7out /en on the 6ing ti,s or tail The correct ,lace to stand to ena9le the aircrafts cre6 to hae sight of the

/arshaller The ,oint at 6hich the aircraft is re;uired to sto,.


o/e (asic Marshalling ignals for Fixed%8ing ircraftFig. 5

Co/e head to, E/ergency to,

+ight Turn ll Clear =-:>eft Turn

+e/oe Choc7s lo6 ?o6n)nsert Choc7s


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2.#.#Fuelling

8hile the to,ic of fuelling is coered /ore fully in Module 11 and in the releantCha,ter =2*> of the Maintenance Manual@ 9rief consideration of so/e of thegeneral safety ,recautions is gien here.

The first@ o9ious ,recaution@ is the identification of the ty,e of fuel in the fueltan7er =or 9o6ser>@ ensuring it is of the ty,e and grade re;uired for the aircraft.There hae 9een /any ti/es 6hen ,etrol%,o6ered aircraft hae 9een filled 6ithtur9ine fuel and@ on occasions@ the reerse has occurred.

The ty,e and grade of fuel should al6ays 9e stencilled or ,ainted@ adBacent to thefuelling ,oint@ 9ut it is 6ise if a res,onsi9le ,erson is consulted 9efore starting

fuelling. This is 9ecause there /ay 9e a re;uire/ent for so/e s,ecial fuel@ orsi/,ly that the aircraft is only to 9e ,art%filled@ due to a 6eight li/itation.

The fuel tan7er /ust 9e ,ar7ed as far as ,ossi9le fro/ the aircraft@ li/ited 9y thehose length@ and ,arallel or facing a6ay fro/ it. This reduces the ris7 of fire,assing fro/ the aircraft to the tan7er or ice ersa@ and also allo6s a clear ,athfor the tan7er to acate the area ;uic7ly@ should the need arise.

The fuel tan7er@ the fuelling hose@ the aircraft and the ground /ust all 9eelectrically 9onded together@ to allo6 the static electricity =generated during thefuel flo6> to run to earth.

safety 4one of / =2 ft> should 9e esta9lished fro/ the filling and enting,oints of the aircraft and attendant fuelling e;ui,/ent. This area should 9e freefro/ na7ed lights@ s/o7ing and the o,eration of electrical s6itches of any 7ind.

There can also 9e a ris7 fro/ the o,eration of radio and radar e;ui,/ent@ sothese should also 9e s6itched off 9efore fuelling co//ences.

lso@ during the fuelling of aircraft@ uxiliary &o6er Units =&U> and 'round&o6er Units@ ='&U>@ /ust 9e /ade safe@ 9y chec7ing that their exhausts and

inta7es are clear of any fuel a,ours@ and that '&Us@ are located as far as,ractical fro/ the fuelling ,oint=s>.

!- s6itching of ,o6er fro/ &Us or '&Us 6ill 9e /ade during fuelling,rocedures.

There are /any ,recautions inoled 6hen defuelling@ due to the tan7s 9eing lefte/,ty of fuel@ leaing ,otentially ex,losie a,ours in its ,lace.

necessary safety ,recautions /ust 9e follo6ed during aircraft fuelling,rocedures.

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2.#.58eather +adar

The heating and radiation effects of 6eather radar can 9e ha4ardous to life.&ersonnel should re/ain a safe distance fro/ the radar if it is in o,eration. Thereare ,u9lished figures and charts in the /aintenance /anual of each aircraft@sho6ing the safe distances for ,ersonnel@ de,ending on the ,o6er of the radar inuse.

s an exa/,le@ the aerial in the nose of the aircraft should hae an uno9structedie6 of so/ething li7e 3 /etres@ 6ith the aerial tilted u,6ards. There shouldalso 9e a 9arrier erected a9out 3 /etres or so fro/ the nose of the aircraft@ to,reent ,ersonnel getting too close.

Finally@ there should 9e no fuelling o,erations in ,rogress during the testing of6eather radar.

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+ ,OR5S/OP PRACTICES

?es,ite the enor/ous adances in the /echanisation and co/,uterisation of theengineering industry in general@ there re/ains the re;uire/ent for a high degreeof hand s7ills on the ,art of technicians 6ho are engaged in the day%to%day/aintenance of aircraft and their associated co/,onents.

8hile the /aBority of aeros,ace co/,onents are /anufactured under stringentstandards@ in factory =and la9oratory> conditions@ it is necessary to re/oe /anyite/s of e;ui,/ent for cleaning@ ins,ection@ oerhaul and@ if needed@ re,air9efore they are@ su9se;uently@ re%installed in their a,,ointed locations.

These actions /ay entail the use of /any s,ecialist tools and /aterials@ 6hichare used 6hile follo6ing 6ritten ,rocedures@ 6hile it is ;uite ,ossi9le that so/e@co/,aratiely si/,le@ re,airs /ay call u,on such 9asic hand s7ills as the cutting@filing@ drilling@ rieting and ,ainting of /etals or other /aterials.

!o /atter 6hether there are s,ecialist or 9asic s7ills re;uired@ all 6ill de/and acertain ;uality of the 6or7 ,ractices =and of the 6or7%force> inoled.

+#1 Ca&e - T--l'

Engineers are res,onsi9le for the /aintenance of their ,ersonal tools@ 6hilst

other ,ersonnel@ in designated Tool tores@ /ust care for all the different@s,ecialist tools for 6hich they hae the res,onsi9ility. )t is also the res,onsi9ilityof engineers to ensure that any tools@ or other ite/s of e;ui,/ent they use@ arenot left in an aircraft or associated co/,onents.

The care re;uired for different tools can ary. -rdinary hand tools /ay /erelyre;uire rac7ing or locating 6ithin sturdy tool 9oxes@ 6ith careful@ daily@/aintenance restricted to little /ore than a isual chec7.

&recision instru/ents ho6eer@ re;uire great care 9oth in storage and in use.They /ay need to 9e 7e,t in s,ecial@ soft%lined@ 9oxes 6ithin other storage

facilities. &rior to use they should hae a 4ero chec7 or cali9ration. o/e toolsre;uire that they hae a light coating of /achine oil@ to ,reent the onset ofcorrosion.

Each tool =6hether it 9e a ha//er or a /icro/eter>@ 6ill re;uire so/e s,ecialcare@ to ensure its o,ti/u/ ,erfor/ance for@ 6ithout this care@ een the /ostex,ensie tools ery ;uic7ly 9eco/e second rate and useless.



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+#$ C-n&-l - T--l'

Control of tools is i/,ortant to good engineering ,ractices and is also ital toflight safety. ariety of syste/s can 9e used to control tools 9ut@ 6hicheersyste/ is used@ it /ust allo6 a 1J chec7 of the tools in use 9efore it can 9econsidered as acce,ta9le.

-ne for/ of control is the shado6 9oard and tool tag syste/@ =refer to Fig. >.Each tool is ,ositioned oer its silhouette@ on the tool 9oard. Technicians areissued 6ith identification to7ens =nu/9ered tags> 6hich are exchanged for thetool and@ usually@ a tag is hung a9oe the silhouette@ to 9e reclai/ed@ in exchangefor the tool@ 6hen it is returned to the 9oard. The shado6 9oardAtool tag syste/6or7s e;ually 6ell 6hen the tools are held 6ithin a designated Tool tore

arrange/ent.

)n 6or7sho,s and 9ays it is nor/al for a tool7it to 9e held 9y the de,art/ent inaddition to its engineers holding ,ersonal sets of tools. The tools held 9y the

de,art/ent are often referred to as s,ecial tools@ /eaning that they are only for/aintenance 6or7 on the ite/s 9eing sericed in that 6or7sho,.

6heel 9ay@ for exa/,le@ /ay hae sets of s,ecial s,anners@ leers@ seala,,licators and ,re%set tor;ue 6renches@ 6hich are used ,ri/arily for thesericing of ,articular ty,es of aircraft 6heels. This dedicated tool 7it /a7es toolcontrol /uch si/,ler and safer@ 6ith the tools all 9eing clearly /ar7ed as9elonging to that s,ecific 9ay.


hado6 (oard and Tool TagFig. 1


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!o /atter 6here tools are 9eing used@ it is the res,onsi9ility of each technician to7ee, trac7 of of the tools used during a ,articular tas7. The /ost i/,ortant

chec7 of all is the final@ End of 8or7 tool chec7@ 6hen all tools /ust 9e collectedand chec7ed off against ,ersonal inentories@ ensuring all 9orro6ed tools =fro/the Tool tore for exa/,le>@ are returned and any ,ersonal tool tags collected.

+#+ Cali&ai-n - T--l' an) E!i.men

+e;uire/ents 6ithin the releant air6orthiness codes@ a,,lica9le to the United:ingdo/ Ciil iation )ndustry@ such as the (ritish Ciil iation +e;uire/ents=(C+s>@ oint iation +e;uire/ents =+s>@ and ir -,erators Certificates@,rescri9e that@ 6here necessary@ tools@ e;ui,/ent and@ in ,articular@ teste;ui,/ent are all cali9rated to acce,ta9le standards.

This to,ic ,roides an oerall ,icture of the ty,es of re;uire/ents and testsre;uired in esta9lishing and /aintaining an effectie cali9ration syste/. )t ta7esinto account factors such as the degree of accuracy re;uired@ fre;uency of useand the relia9ility of the e;ui,/ent.

The 7ey factor is the need to esta9lish confidence in the accuracy of thee;ui,/ent 6hen it is re;uired for use. The re;uired cali9ration fre;uency for any,articular ,iece of test e;ui,/ent is that 6hich 6ill ensure it is in co/,liance 6iththe standards a,,lica9le to its intended use. )n all cases@ standards used areattri9uted u,on the need for ulti/ate tracea9ility to one of the follo6ing

The standard s,ecified 9y the e;ui,/ent /anufacturerAdesign organisation The a,,ro,riate !ationalA)nternational tandards.

3.3.1'eneral !otes on Cali9ration

The a,,ro,riate standards are used to achiee consistency 9et6een/easure/ents /ade in different locations@ ,ossi9ly using alternate /easuringtechni;ues. The cali9ration of test e;ui,/ent is 9est achieed 9y the o,eration ofa /ethodical syste/ of control.

This syste/ should 9e tracea9le 9y an un9ro7en chain of co/,arisons@ through/easure/ent standards of successiely 9etter accuracy u, to the a,,ro,riatestandard. 8here reco//endations for cali9ration standards are not ,u9lished@ or6here they are not s,ecified@ cali9ration should 9e carried out@ in the U:@ inaccordance 6ith (ritish tandard E! 312%1 Kuality ssurance +e;uire/entsfor Measuring E;ui,/ent.

s an alternatie to o,erating an internal Measure/ent and Cali9ration yste/@an ,,roed -rganisation or an ,,roedAicensed Engineer /ay enter into asu9%contracting arrange/ent to use an ,,liance Cali9ration erice. This

arrange/ent does not a9sole the contractors of the serice fro/ /aintainingstandards as if they 6ere carrying out the 6or7 the/seles.



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)n all instances@ it is the res,onsi9ility of the user to 9e satisfied that the un9ro7entracea9ility chain is in ,lace. External organisations@ 6hich su,,ly an external

Cali9ration erice@ should 9e those holding accreditation of the !ationalccreditation of Measure/ent and a/,ling@ =!M>.

3.3.2&rocedures

The definition of a,,liances re;uiring cali9ration are those ite/s 6hich arenecessary to ,erfor/ /easure/ents or tests of an aircraft@ a syste/ or aco/,onent@ to defined li/its@ as s,ecified in the technical docu/entation of theTy,e Certificate holder.

&rocedures@ controlling regular ins,ection@ sericing and@ 6here a,,ro,riate@

cali9ration of such ite/s@ are to indicate to the users that the ite/ is 6ithin anyins,ection ti/e li/it. These !ext )ns,ection la9els /ust clearly state 6hen@ and@if necessary@ 6here the next cali9ration is due.

There should 9e a ,rogra//e that ,lans the ,eriodic ins,ection@ serice orcali9ration 6ithin the defined ti/e li/it@ 6hich ensures that the ite/ re/ains incali9ration. )t is co//on sense to stagger the cali9ration of ite/s@ so that thelargest nu/9er are aaila9le for use at all ti/es. )t is also i/,ortant@ that aregister of all ite/s re;uiring cali9ration is held@ so that cross%chec7ing can 9esi/,ly carried out. 8here a s/all nu/9er of ,articular ite/s are held@ thencontract loan of e;ui,/ent is ,er/itted.

The interals at 6hich cali9ration is re;uired@ can ary 6ith the nature of thee;ui,/ent@ the conditions under 6hich it is used and the conse;uences ofincorrect results. The fre;uency 6ill 9e in accordance 6ith the /anufacturer orsu,,liers instructions@ unless the organisation can sho6 that a different interal is6arranted in a ,articular case. This 6ould nor/ally re;uire a syste/ ofcontinuous analysis of cali9ration results to 9e esta9lished@ to su,,ort theariation to the reco//ended cali9ration interals.

ny a,,liance@ the sericea9ility of 6hich is in dou9t@ should 9e re/oed fro/

serice and clearly la9elled accordingly. The a,,liance /ust not 9e returned toserice unless the reason for its unsericea9ility has 9een eli/inated and itscontinued cali9ration re%alidated. ction /ust 9e ta7en@ if an ite/ of e;ui,/entis found@ during re%cali9ration@ to hae a significant error. This /ust include re%chec7ing of /easure/ents /ade ,rior to finding the fault.

The sco,e of the records /aintained@ are de,endent u,on the standards re;uiredand the nature of the e;ui,/ent. The record syste/ can also ,roide a alua9lereference in case of dis,ute or 6arranty clai/s. These records can also indicatedrift and can hel, in reassessing cali9ration interals.



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Cali9ration records or certificates should@ as a /ini/u/@ contain the follo6inginfor/ation for each a,,liance cali9rated

)dentification of e;ui,/ent

i/its of ,er/issi9le error

tandard used

uthority under 6hich the docu/ent 6as issued

+esults o9tained

ny li/itation of use of e;ui,/ent

Uncertainty of /easure/ent

?ate 6hen each cali9ration 6as conducted

ssigned cali9ration interal.

8here cali9ration serices are ,roided 9y outside organisations@ it is acce,ta9lethat the accuracy of the e;ui,/ent is attested 9y a release docu/ent in the na/eof the Cali9ration Co/,any.

ny /easure/ent is affected@ to so/e degree@ 9y the eniron/ent in 6hich it is/ade. The e;ui,/ent 6ill need to 9e cali9rated@ trans,orted and stored underconditions co/,ati9le 6ith the ty,e of e;ui,/ent@ to ensure its accuracy is noti/,aired.

To ,roide alid and re,eata9le test results@ the facilities used for cali9ration /ust

hae a controlled eniron/ent. )t is necessary to control the te/,erature@hu/idity@ i9ration@ dust@ cleanliness@ electro/agnetic interference@ lighting andother factors that /ay affect the standard of the results. )f any of thesere;uire/ents cannot 9e /et@ then co/,ensation corrections /ust 9e a,,lied tothe cali9ration standard to ensure continued accuracy.

/easure/ent Chec7ing tandard can 9e a,,lied@ at the 6or7 ,lace@ to chec7the accuracy of an a,,liance and to ensure its continued correct functioning. TheChec7ing tandard 6ill 9e ro9ust and its accuracy 6ill not /atch that of a fullcali9ration chec7@ 9ut it 6ill gie confidence 9et6een chec7s that the e;ui,/ent isfunctioning correctly.

The co/,any Kuality yste/ has the res,onsi9ility of ensuring the continuedaccuracy@ not only of the ite/s of e;ui,/ent@ 9ut also of the actual testingfacilities.



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+#3 U'e - ,-&"'h-. Mae&ial'

Many of the 6ide ariety of /aterials@ used in 6or7sho,s@ re;uire so/e for/ ofcontrol in their handling. This control can inole

afety relating to such to,ics as the toxicity@ corrosieness or other healthris7s associated 6ith the use of certain /aterials

Manage/ent referring to the storage@ use and correct handling of all/aterials 6hether they are solid@ li;uid@ or@ in so/e instances@ gaseous

Econo/y inoling such /atters as to the using of the correct dosage or,ro,ortions 6hen /ixing co/,ounds@ using only as /uch /aterial as re;uiredfor a s,ecific tas7 and to the 7ee,ing in stoc7 of only sufficient /aterials andthus aoiding lifed ite/s reaching their ex,iry dates 9efore 9eing used.

9rasie ,a,ers@ solder and 9ra4ing /aterials@ 6ire 6ool@ tyre ,o6der@ oil s,ill,o6der and so on@ all re;uire control of issue and use@ though they /ay not@nor/ally@ re;uire stringent safety ,recautions.

huge range of li;uids can 9e used in the 6or7sho, situation@ so/e of 6hich arehar/less and so/e of 6hich are extre/ely toxic. )t is ital that the 6or7%force/a7e the/seles a6are of the ris7s inoled 6hen dealing 6ith ! /aterials@

and es,ecially 6hen 6or7ing 6ithin enclosed areas.

o/e /aterials are fla//a9le and /ust@ therefore@ 9e stored outdoors. Theseinclude oils@ greases@ so/e adhesies@ sealing and gla4ing co/,ounds inaddition to /any ,aints@ ena/els and e,oxy surface finishes@ 6hich are stored in/etal ca9inets and@ usually@ located =in the !orthern he/is,here> on the !orthside of a 6or7sho, or hangar. This ensures that the ca9inet re/ains in the shadeof the 9uilding and does not get ex,osed to the suns hot rays during the day. )t isalso i/,ortant that only the /ini/u/ a/ount of these /aterials is ta7en indoorsfor the 6or7 6hich is 9eing done.

8hen handling /aterials that gie off fu/es@ it /ay 9e necessary to hae thearea 6ell entilated andAor hae the o,erator 6earing a /as7 or so/e for/ ofre/ote 9reathing a,,aratus. The finished 6or7 /ay also gie off fu/es for so/eti/e after6ards@ so care /ust 9e ta7en to 7ee, it entilated if necessary.

-9iously all li;uids /ust only 9e used for the ,ur,ose for 6hich they aredesigned and neer /ixed together@ unless the t6o /aterials are designed to 9e/ixed@ such as 6ith t6o ,art e,oxy adhesies and sealants.Many li;uids used in 6or7sho,s and in the hangar hae =as /entioned earlier> afixed life. This date is ,rinted on the container and /ust 9e chec7ed 9efore use@9ecause /any /aterials are unsafe if used 9eyond their ex,iry date.



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The dis,osal of li;uids is a critical o,eration@ and /ust only 9e carried out inaccordance 6ith co/,any =and@ often@ national or international> regulations.

i;uids /ust neer 9e dis,osed of 9y ,ouring the/ into s,are or unidentifiedcontainers and they /ust not 9e allo6ed to enter the do/estic drains syste/s.

The 6or7ing 6ith@ and the use of@ high ,ressure gas containers and oxygensyste/s@ 6as ade;uately discussed in the afety &recautions to,ic.

+#* San)a&)' - ,-&"man'hi.

8hilst the standards of 6or7/anshi,@ during the hand%6or7ing of /etals andother /aterials@ is controlled 9y the crafts,erson@ once /achinery is used in the

/anufacturing ,rocess@ then the standards of finish and 6or7/anshi, de,endu,on the allo6ances set 9y the designer and on the ty,e of /achinery 9eingused.

8ith hand tools@ there are standards of finish@ 9ut these de,end u,on the s7ill ofthe crafts,erson and@ again@ on the tools 9eing used. For exa/,le@ 6hen filing/etal@ different grades of files are used@ to o9tain a co/,aratiely s/ooth surfacefinish 6hile other /ethods@ such as a9rasie ,a,ers@ ,astes and ,olishes@ arethen used@ to ,roide the final finish.

8hen sa6ing@ the sa/e ,rocedures a,,ly in that 9lades 6ith finer teeth 6ill giea 9etter finish to the sa6n edges@ 6hich /ay then 9e further s/oothed@ using ana,,ro,riate selection of files.

8hen drilling a hole@ the conentional t6ist drill 6ill only ,roduce a finish of acertain standard. )f a finer finish@ to the inside of the hole@ is re;uired@ then area/er 6ould 9e used@ to s/ooth the /aterial inside the hole@ so that@ if a tightfitting ,in is to 9e fitted through the hole@ there 6ill 9e 9etter surface contact.

There are a ariety of /achines that can generate a s/ooth surface on a ,iece of/etal@ the selection 9et6een the/ 9eing decided 9y the ;uality of finish. lathe

can ,roduce an exce,tionally s/ooth surface on a 9ar or so/e other rotatedsha,e. )f a large area is re;uired to hae a s/ooth finish@ then ,erha,s@ afterinitial casting or forging@ the choice /ay 9e of e/,loying either a grinding/achine or a /illing /achine@ to .,roide the desired result.

)n su//ary@ the ;uality of the finished article is de,endent 9oth on the s7ill of thecrafts,erson and the e;ui,/ent aaila9le to co/,lete the tas7. )t does not /atter6hether the tools in use are files and e/ery cloth or an ex,ensie /illing/achineL the standard of 6or7/anshi, of the crafts,erson can /a7e a great dealof difference to the finished article.



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&'E

)!TE!T)-!(!:.



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#.1.2cri9er

scri9er =refer to Fig. 2> is used for /ar7ing lines on the surface of /etals.cri9ers are /ade fro/ high%car9on steel and are classified 9y their length. -neend of the scri9er is usually 9ent at right angles to ena9le lines to 9e scri9ed indifficult ,laces such as through a hole.

ll scri9ed lines@ on soft /aterials@ /ust only 9e cutting =9oundary> lines@ andnone /ust 9e left on the surface of the /etal on co/,letion@ as they can causecrac7s. -ther lines@ including 9end lines and lines for the ,osition of riets /ust9e /ar7ed 6ith a shar, ,encil.

cri9er ,oints /ust 9e 7e,t shar, and fine 9y careful stoning@ 6ith an oil stone@

rather than an a9rasie 6heel =grindstone>. Using a 6heel is li7ely to generate too/uch heat@ 6hich 6ill result in the te/,er 9eing dra6n fro/ the steel and the,oint of the scri9er 9eco/ing soft and useless.

8hen not in use =and as 6ith other tools 6ith shar, ,oints>@ ,lacing ,ieces ofcor7@ ,lastic or si/ilar /aterial oer their ,oints 6ill ,rotect the/.

#.1.3:ey%eat +ule

:ey%seat rules are used for /ar7ing%off lines@ ,arallel to the axis@ on the surfaceof tu9es or round 9ars =refer to Fig. 2>. o/eti/es referred to as (ox ;uares@7ey%seat rules are usually graduated and are classified 9y their length.


cri9er and :ey eat +ule

Fig. 2

+ound (ar

:ey eat+ule

cri9er


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#.1.#Fitters ;uare

The fitters s;uare is used for setting out lines at right angles to an edge orsurface@ and for chec7ing right angular 6or7 for truth. ;uares are /ade@ to eryfine li/its@ of high%car9on steel and are classified 9y the length of the 9lade.

The 9lade and the stoc7 hae their o,,osing edges ground truly ,arallel 6ith the

t6o li/9s set at exactly 0to each other.

To ,resere its accuracy it is essential that it is handled carefully at all ti/es and@6hen not in use@ 7e,t in a ,rotectie case or 9ox.

8hen testing a s;uare for accuracy@ it /ay 9e chec7ed for truth against an

accurately /achined right angular test ,iece such as a as follo6s

&lace the stoc7 against the true edge of a flat surface and scri9ing a line onthe surface@ using the outside edge of the 9lade

Turn the s;uare oer and chec7 the outside edge of the 9lade against the,reiously scri9ed line.

)f the s;uare is accurate@ the 9lade edge and the scri9ed line 6ill 9e in line. )n asi/ilar /anner@ the inside edge of the 9lade can 9e tested.


Error

True Edge

Testing a ;uareFig. 3


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#.1.5Co/9ination et

The Co/9ination et =refer to Fig. #>@ consists of a graduated steel rule@ 6hichhas a /achined grooe running along the centre of its entire length. The rule can9e slid into three different heads and secured@ 9y a loc7ing scre6 deice@ so thatthe co/9ination of rule and head 6ill ena9le certain tas7s to 9e acco/,lished.

The Centre $ead is used@ 6ith the rule@ to locate the centre line of 9ars or roundtu9es.

The ;uare $ead has one 6or7ing surface at 0 and another at #5 to theloc7ed rule. This allo6s the tool to 9e used@ either in a si/ilar /anner to theFitters ;uare =to chec7 the s;uareness of 6or7>@ or it /ay 9e used for the

/ar7ing out of /itre Boints and 9eels.

s,irit leel and scri9er are@ so/eti/es@ acco//odated in the 9ase of the;uare $ead@ to ,er/it a chec7 to 9e done on the hori4ontal or ertical accuracyof 6or7,ieces.

The &rotractor $ead also has a s,irit leel@ 6hich rotates 6ith the head@ andallo6s the head to 9e used@ singly@ as a clino/eter or@ in conBunction 6ith the rule@it /ay 9e used to /ar7 out and chec7 angles on 6or7,ieces.


Co/9ination et

Fig. #

Centre $ead;uare $ead

cri9er

,irit eel

'rooe

&rotractor $ead


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#.1.urface &lates and Ta9les

urface ,lates =and surface ta9les 6hich are larger>@ 6hile not actually 9eingclassed as /ar7ing out or /easuring tools@ are si/,ly 9loc7s of grey cast iron6ith finely /achined faces 6hich can 9e used as a standard of flatness. They/ay also 9e used to ,roide a true surface@ fro/ 6hich /ar7ing out@ /easuringand testing can 9e done.

urface ,lates are usually /ounted on a 9ench and@ nor/ally@ only hae threesu,,orts@ or feet@ to ensure steadiness@ if the surface of the 9ench 6ere to 9eslightly uneen.

urface ta9les are free standing@ on the 6or7sho, floor@ and their sheer 6eight

,roides the re;uired steadiness.

The standard of the surface finish aries. The 9etter grades are scra,ed and thechea,er ones are /erely ,laned. The accuracy of a ,laned ta9le de,ends u,onthe accuracy of the /achine ,roducing it.

urfaces of grade standard 6ould only 9e used in tandards +oo/s@ grade (surfaces are for ins,ection 6or7 6hile grade C surface ,lates and ta9les 6ould9e found in ty,ical 6or7sho,s.

urface ,lates and ta9les can 9e used to test for flatness@ ,roiding the standardsre;uired are not too high. The surface of the ,late is lightly s/eared 6ith a/ixture of engineers 9lue and a fe6 dro,s of oil. The ,iece to 9e tested has to 9eru99ed lightly on to the surface ,late and any high s,ots 6ill sho6 u, as 9lues,ots on the test ,iece. These s,ots 6ill 9e filed or scra,ed until the 6holesurface sho6s 9lue.

fter use@ a light fil/ of oil should 9e a,,lied to the 6or7ing surface of the surface,lates and ta9les. They should@ then@ 9e ,rotected 6ith a 6ooden coer@ to,reent the onset of corrosion.

#.1."< (loc7s

< (loc7s are accurately /achined@ six%sided@ rectangular 9loc7s =generally /adeof cast iron>@ 6hich /ay 9e used@ on surface ,lates and ta9les@ to hold a round9ar@ 6hich can then 9e /ar7ed in a ariety of 6ays@ to gie centres and lines,arallel to its side. < 9loc7s are classified 9y the /axi/u/ dia/eter of the 6or7@6hich they can hold.

ll o,,osite sides of the 9loc7s are ,arallel and all adBacent faces are s;uare toeach other. 0 grooe =in the sha,e of a is /achined in t6o =longer>o,,osite faces@ 9ut the grooes are cut at different de,ths@ to cater for 9ars of

different dia/eters.



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The @ is another /ar7ing out tool@used@ on a surface ,late or ta9le@ in conBunction 6ith a scri9er =and@ occasionally@6ith < 9loc7s>@ for the /ar7ing of lines@ 6hich are ,arallel to a true surface.

The scri9er is cla/,ed to a s,indle@ 6hich can 9e accurately ,ioted@ 9y /eansof a fine adBust/ent scre6@ on the heay 9ase. The 9ase@ 6hich is generally/ade fro/ cast iron =or hardened steel> is /achined to 9e as flat as the surface,late on 6hich it slides@ 9ut it is also grooed =in a si/ilar /anner to the < 9loc7>so that it can 9e used on round stoc7 6hen re;uired.

T6o friction%fit ,ins@ in the 9ase@ /ay 9e ,ushed do6n@ to assist in dra6ing lines,arallel to a true edge.


cri9ing (loc7 6ith < (loc7s and urface &late

Fig. 5

cri9ing (loc7

< (loc7s

urface &late


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#.1.0?iiders

?iiders are used to set out distances and to scri9e arcs and circles. The legs are/ade of high%car9on steel@ the s,ring /ade of s,ring steel and the adBusting/echanis/ of /ild steel.

?iiders are classified 9y the length of their legs. The ,oints should 9e 7e,t shar,and of e;ual length 9y stoning only the outside of the legs. )f grinding is used toshar,en the ,oints@ it /ust 9e done ery carefully@ as the te/,er of the ,oints can9e dra6n@ leaing the/ soft.

The ,oints of diiders should 9e ,rotected@ 6hen not in use@ in a si/ilar /annerto those of scri9ers and such tools.

#.1.1 Calli,ers

Calli,ers =refer to Fig. > are a ty,e of /easuring deice@ ty,ically used to/easure dia/eters and distances or for co/,aring si4es. The three 9asic ty,esof calli,er are

-utside Calli,ers Used to /easure the outside dia/eter of an o9Bect andhae legs that ,oint in6ards

)nside Calli,ers Used to /easure the inside of a hole and hae legs that ,oint

out6ards -dd%eg Calli,ers =$er/a,hrodite or enny Calli,ers> This tool is really halfcalli,ers and half diiders. )t /ay 9e used for scri9ing arcs on /etal surfacesfro/ an edge@ for scri9ing lines ,arallel to an edge or surface@ =,roidedaccuracy is not of great i/,ortance>@ and for finding the centre of a round 9ar.


-utside )nside -ddleg

Calli,ersFig.


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#.1.11 $a//ers

$a//ers =refer to Fig. "> are classified 9y their 6eight and ty,e of head. teelheads are forged and /anufactured fro/ high%car9on steel. Most shafts are/ade fro/ straight%grained sh or $ic7ory and are secured to the head 9y6edging.

s can 9e seen fro/ Fig. "@ the /ain ty,es of engineering ha//ers are the

(all &ein The flat surface is used for /ost general%,ur,ose 6or7 6hilst the9all ,ein is used ,ri/arily for rieting%ty,e o,erations

traight &ein Used for general 6or7@ the narro6@ straight ,ein 9eing,articularly suita9le for use 6here access to the 6or7 is li/ited


Ty,es of $a//ersFig. "

(all &ein traight &ein Cross &ein

$ideACo,,erFace

&lastic Face

$ide Face+u99er $ead


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Cross &ein s for the straight ,ein@ 9ut the axis of the ,ein is at 0 to that ofthe shaft

$ideACo,,er Face The ra6hide facing ena9les heay 9lo6s to 9e deliered6ithout da/aging the surface of the 6or7@ 6hile the co,,er face /ay 9e usedfor heaier ty,es of 6or7 than hide faced ha//ers

+u99er $ead and &lastic Face More /odern ersions of the $ide Faceha//er. Can often hae one of each ty,e of face on each end of the head

Cla6 $a//er =not sho6n> More co//only used for 6ood6or7ing. The faceis used for ha//ering nails 6hilst the cla6 is used for re/oing nails

(ody $a//er =not sho6n> ittle used in aircraft 6or7@ as they are ,ri/arilyused to re/oe dents and 9le/ishes fro/ sheet /etal. They are also 7no6nas ,lanishing ha//ers.

The 6eight of ha//er re;uired can 9e found 6ith ex,erience. (efore use@ it /ust9e ensured that the head is secure on the shaft. The shaft should 9e gri,,edclose to the end o,,osite the head@ as ,ro,er control is not ,ossi9le if it is heldclose to the head.

#.1.12 &unches

lthough ,unches are not ,ounding tools@ they do allo6 the force fro/ aha//er 9lo6 to 9e concentrated in the i//ediate area of the ,unch ti,. This inturn /eans that the ,ressure at the end of the ,unch is increased co/,ared to a

ha//er 9lo6 6ithout a ,unch.

-er a ,eriod of ti/e@ the ha//ered shan7 end of a ,unch@ tends to defor/ intothe sha,e of a /ushroo/. To reduce the chance of a /etal chi, flying off andcausing inBury@ during ,unching o,erations@ the defor/ation should 9e re/oedand the shan7 end returned to its original sha,e 9y the use of a 9ench grinder.

Eye or face ,rotection should al6ays 9e used 6hen using ,unches of any ty,e.

The ty,es of ,unches@ /ore co//only found in an engineers tool7it@ include

Centre &unches &in &unches

$ollo6 &unches

?rifts

The first three ,unches are@ usually@ constructed fro/ hexagonal =or 7nurled@round> rods of te/,ered@ cast steel 6ith a length of a,,roxi/ately 12" // =5 in>@a gri,,ing dia/eter of a,,roxi/ately 3.1"5 // =.125 in> and a s/aller@ driingend of the a,,ro,riate si4e.



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Centre &unches are relatiely shar,%,ointed tools@ used to /a7e an indentation in/etal. The indentation aids in locating the centre of a hole and for starting a drill

9it 6hen drilling the hole. The ,oints /ay 9e ground at angles 9et6een to 0@de,ending on the hardness of the /etal on 6hich the ,unch is 9eing used. Thesofter the /etal@ then the larger 6ill 9e the angle of the ,unchs ,oint.

8hen using a centre ,unch@ it /ust 9e struc7 hard enough to gie an indentationlarge enough for a drill 9it to start@ 9ut not so hard as to distort the /etal.

nother for/ of Centre &unch is the ?ot or &ric7 &unch =also &ric7er>@ 6hichhas a finer ,oint and is used to /a7e indentations along a dra6n line 6hen theline is@ other6ise@ difficult to see. The indentations /ay also 9e used@ 6hensa6ing do6n to a line@ as 6itness ,oints@ to sho6 that the cutting is accurate.

Centre ,unches should not 9e used to drie out ,ins or riets fro/ their holes.

&in &unches@ as their na/e i/,lies@ are the tools to 9e used for the re/oal of,ins and riets fro/ their res,ectie holes. The driing end of a &in &unch is cutflat@ and its dia/eter ground to /atch that of the ,in or riet 6hich is 9eing drienfro/ its hole. &in &unches /ay 9e found 6ith ,arallel or ta,ered driing ends.

$ollo6 &unches are used to ,unch out 9olt =or stud> holes in soft@ thin sheets@such as shi//ing or gas7et /aterials@ 6hich are difficult to cut 6ith drills. The

/aterial 9eing cut@ should 9e su,,orted 9y a 6ooden 9loc7@ to aoid da/agingthe cutting end of the $ollo6 &unch.

?rifts /ay 9e fashioned fro/ alu/iniu/ alloy@ co,,er or steel 9ars =or tu9es>@ andare used for driing out 9earings@ 9ushes or shafts fro/ their res,ectie cages orhousings.

-nly steel drifts should 9e used on 9earings@ due to the ,ossi9ility of s/all /etalchi,s@ fro/ the softer /etals@ 9rea7ing off and fouling the 9earing asse/9lies.

#.1.13 Metal%Cutting Chisels

Metal%cutting chisels =also called Cold Chisels> are used in conBunction 6ith steelha//ers. Chisels are forged@ usually using short lengths of hexagonal%sectioned@high%car9on steel 9ars@ 6ith the cutting edge hardened and te/,ered.

To ,reent flying ,articles 6hen ha//ering@ the stri7ing end is not hardened andis@ therefore@ co/,aratiely softer. &eriodically@ the 9urr@ that for/s at the stri7ingend of the chisel@ should =in a si/ilar /anner to ,unches>@ 9e re/oed 9y filing orgrinding.

lternatiely@ the chisels /ay 9e /ade of nic7el%alloy steel@ s,ecially heat%treated@

to ,roduce a long%lasting cutting edge.



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Chisels are classified 9y their sha,e@ oerall length@ cross%section of shan7 and6idth of cut. There are four ,rinci,al sha,es of chisels =refer to Fig. *>@ in general

use. They are the

Flat

Cross%Cut

?ia/ond%&oint

$alf%+ound.

Flat chisels are used for general chi,,ing 6or7@ such as ,arting sheet /etal orcutting flat surfaces@ ,re,aratory to filing. The cutting edge is for/ed slightlyconex.

Cross%Cut =or Ca,e> chisels are used to cut narro6@ flat%9otto/ed@ grooes@ suchas 7ey6ays in shafts or 6here it is not ,ractical to use a flat chisel. These chiselsare also used to re/oe the heads of round%headed riets during re,airs.

?ia/ond%&oint chisels are ,articularly useful for cutting in corners@ cutting s/alloil grooes and for rectifying an incorrect start 6hen drilling.

$alf%+ound =and /ay@ also@ 9e called +ound> chisels are general%,ur,ose@grooing chisels@ 6hich are suita9le for cutting half%round@ 9otto/ed@ grooes.They are also suita9le for rectifying an incorrect start 6hen drilling.

8hen selecting a chisel for a s,ecific tas7@ consideration /ust 9e gien 9oth tothe nature of the 6or7 and to the /aterial that is to 9e cut. The nature of the 6or7goerns the choice of sha,e@ 6hilst the angle for/ed 9y the cutting edge isinfluenced 9y the hardness of the /etal.


$alf%+ound?ia/ond%&ointCross%CutFlat

Chisel Ty,esFig. *


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)n general@ it /ay 9e assu/ed that the softer the /etal the /ore acute should 9ethe cutting angle. Ta9le 5 sho6s so/e suggested cutting angles for use on

ty,ical /etals@ found in aircraft engineering 6or7sho,s.

Ta9le 1U''ETE? C$)E CUTT)!' !'E

$ard teels "

Mild teels

oft Metals #

$igh%car9on@ steel chisels@ should 9e shar,ened 9y grinding on an a9rasie6heel@ 9ut nic7el%alloy@ steel chisels are shar,ened 9y filing. The cutting edge of

the chisel /ust 9e 7e,t cool@ during grinding@ 9y fre;uent i//ersion in 6ater@6hich 6ill ,reent the te/,er 9eing dra6n fro/ the /etal.

#.1.1# (ench is used to fir/ly gri, the /aterial or ite/ u,on6hich 6or7 is 9eing done in a 6or7sho,. The 9ody of the ice is ,roided 6ithdetacha9le steel Ba6s. The scre6 is /ade 6ith a s;uare or 6ith a 9uttress thread.

Most ty,es of 9ench ice hae a ;uic7%release /echanis/@ o,erated 9y a s/allleer. The Ba6s can then 9e slid either o,en or closed until the correct ,osition is

reached. The leer disengages the half nut fro/ the thread to ,er/it the slidingaction and it is drien 9ac7 into engage/ent 9y a strong s,ring. (ench ices areclassified 9y the length of their Ba6s.

The height of the to, of the ice a9oe the ground is i/,ortant@ and shouldideally@ 9e leel 6ith the technicians el9o6 6hen standing adBacent to the ice.8ith the ice at the correct height@ 6or7 6ill 9e less tiring and correct control ofthe tools@ such as files and sa6s@ 6ill 9e achieed.

The ice /ust 9e secured fir/ly to the 9ench =6ith occasional chec7s of theholding%do6n nuts>@ and the scre6 should 9e 7e,t clean and lu9ricated. The Ba6s

/ust not 9e oer%tightened as the /echanis/ /ay 9e da/aged or the 6or7,iece9eco/e distorted.

To ,rotect soft /aterials fro/ the hardened@ serrated@ ice Ba6s@ alu/iniu/ icecla/,s =or cla/s> can 9e ,ositioned oer the Ba6s. -ther@ s,ecial holdingdeices@ such as can 9e/anufactured locally.



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#.1.15 $and is classified 9y its oerall length and can 9e used6hen s,licing ca9les or holding s/all o9Bects that are to 9e sha,ed or drilled. The9ody and scre6 are /ade of /ild steel@ 6ith a 6ing nut ,roided for the o,erationof the hand ice. /all ice cla/,s can also 9e used 6ith these ices 6hen6or7ing 6ith soft /aterial.


(ench


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#.1.1 $ac7sa6s

The hac7sa6@ is the /ost 6idely%used@ /etal%cutting@ hand sa6. $ac7sa6s areused for ,arting off@ or for cutting /aterials a,,roxi/ately to si4e. They aredesigned ,ri/arily for cutting /etal@ 9ut /ay 9e used on other /aterials. The sa6consists of a /ild steel fra/e@ 6ith a suita9le handle and a re,lacea9le@ serrated9lade@ 6hich is /ade fro/ high%car9on or alloy steel.

Fine%toothed 9lades hae 2# or 32 teeth ,er inch and are used for cutting thin/aterial. Coarser 9lades@ 6ith 1# or 1* teeth ,er inch are for thic7er /aterial. rule of thu/9 is that at least t6o teeth /ust 9e in contact@ 6ith the 6or7 9eingcut@ at all ti/es =refer to Fig. 11>.

The 9lade /ountings /ust 9e set in the /ost conenient ,osition 6ith the teethfacing a6ay fro/ the handle. This allo6s the 9lade to cut on the /ore efficient@for6ard stro7e.

$and ,ressure should 9e a,,lied on this for6ard stro7e and relieed on thereturn stro7e. The full length of the 9lade should 9e used for each stro7e@ if at all,ossi9le. This action ,rolongs the life of the 9lade@ lessens the chance of teeth9rea7ing a6ay fro/ the 9lade and reduces the chance of the sa6 Ba//ing during

use.

&age 1# "1*111"5.doc )ssued ?ece/9er 22

$ac7sa6 Teeth in Contact 6ith 8or7,ieceFig. 11

Thinner ections % More Teeth ,er )nch

Thic7er ections % ess Teeth ,er )nch


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JAR 66 CATEGORY B1

MODULE 7


!"engineering

a6 9lades are gien an alternate set@ during /anufacture@ 6hich results in thecutting slot =the 7erf> 9eing 6ider than the 9lade thic7ness =refer to Fig. 12>. This

,reents the 9lade fro/ Ba//ing@ 6hich /ay result in a 9ent or 9ro7en 9lade.

#.1.1" heet Metal hears and ni,s

hears are another ty,e of cutting tool used on aircraft sheet /etal. ong@straight cuts@ across a ,iece of sheet /etal@ are /ade on a guillotine@ 6hich /ayalso 9e referred to as s;uaring shears.

The fa9rication of s/aller ,arts re;uires hand cutting@ follo6ed 6ith furthertri//ing to the final di/ensions. This can 9e achieed 6ith diffe

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68831900 Module 07 B1 Mechanical Book 1

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