TOOLS

Aircraft engineers deals with very specified and calibrated tools in their day to day life for the  serving of aircraft. For  Dismantling, examination, reassembly of the aircraft parts and components in accordance with the  maintenance time period these tools should be calibrated and must be available at work place . A reasonable degree of skill,in the use of hand tools is, therefore, to be expected from all trades-persons.                   
COMMON HAND TOOLS:
1. ENGINEER'S RULE: It is made from high carbon steel and is classified by length and width of their graduated portion. It has a length  of 300 mm or 1 fit and can be found at 1800 mm or 6 fit.
2. SCRIBER:  It is used for making lines on the surface of metals. It is made up of high carbon steel and classified by their lengths.

3. KEY-SET RULE : It is used for making off parallel lines to the axis on the surface of tubes. These are classified by their length.

4. FITTER SQUARE: It is used for setting out lines at right angle to an edges or surface. It is made up of high carbon steel and classified by the length of the blade.

5. COMBINATION SET:  It consists of grooved scale. The center  head is used with the rule to locate the center line on the bar. The square head has one working surface at 90 degree another at 45 degree to the locked rule. It has a sprite level to permit a check to be done horizontal or vertical accuracy. The protector head also have a sprite level.

6. SURFACE PLATES AND TABLES: These are used to make the surface smooth and flat.

7. V-BLOCKS:  These are accurately machined , rectangular blocks. It holds a round bar to give central lines parallel to its sides.

8. SURFACE GAUGE: It is also called scribing  blocks. It uses v blocks  for making lines which are parallel to a true surface.

9. DIVIDERS: It is used to set out distances and to scribe arc  and circles. The legs are made up of high carbon steel, the spring made of spring steel and the adjusting materials of mild steel.

10. CALIPERS: It is used to measure the diameter and distances. The basic types of calipers are:
I. Outside caliper : Used to measure the outside diameters and legs are pointed inwards.
II. Inside caliper: Used to measure inside diameter and legs are pointed outwards.
III. Odd leg caliper also called hermaphrodite or Jenny caliper. It is half caliper and half divider. It is used for scribing arc on metal surface.

11. HAMMER: It is classified by its weight and head type.  Steel head are made up of high carbon steel. There are different types of hammer and are:
I. BALL PEIN: Flat surface is used for general work whilst the ball pein is used for riveting type operation
II. STRAIGHT PEIN: Used where access to the work is limited.
III. CROSS PEIN: The axis of pein is 90 degree to that of the shaft.
IV. HIDE/COPPER FACE: Copper face may be used for heavier types of work than hide faced hammers.
V. RUBBER HEAD AND PLASTICS: More modern version of hide face hammer .
VI. CLAW HAMMER: More commonly used for woodworking. The face is used for hammering nails and the claws are used for removing nails.
VII. BODY HAMMER: These are used to remove dents and blemishes from sheet metal.
VIII. DEAD BLOW HAMMER: Used when the inertia  of the hammer impact need to be absorb to prevent the hammer bouncing.

12.  PUNCHES:= These are used to put lining on the metal sheet for cutting or drilling. These are mostly found it in engineer toolkit . The type of punches are:
i. Center punches : Used to make indentation on the metal to drill. It should not be used to drive out pins or rivets.
ii. Pin punches: These are used to remove the pins and rivets.
iii. Hollow punches: These are used to punch out bolts holes in soft thin sheet.
iv. Drifts: It may be fashioned from aluminium alloy, copper or steel brass and used for driving out bearings bushes or shaft.

13. METAL CUTTING CHISELS:  These are also called cold chisel, and are used in conjunction with steel hammer. It is made up of high carbon steel with cutting edge hardened and tempered. These are classified by their length, shape, cross section of shank and width of cut. Four principal shapes of chisels are:
i. FLAT:  Used for general chopping work, cutting flat surfaces.
ii. CROSS CUT: Used to cut narrow , flat bottomed. Grooves such as key ways  in shaft and also used to remove head of the round headed rivet.
iii. DIAMOND POINT: Used for cutting corners , cutting small oil grooves.
iv. HALF ROUND : Used for general purpose such as for grooving.
 => Chisel has a cutting angle depending upon the materials.
a. Hard steel : It has point angle 70 degree and inclination angle 40 degree.
b. Mild : It has point angle of 60 degree and inclination angle of 35 degree.
c. Soft steel: It has a point angle of 40 degree and inclination angle of 30 degree.

14.  BENCH VICE:  It is used to firmly grip the material or item upon which work is being done.

15  .HAND VICE: A hand vice is classified by its overall length and can be used when splicing or holding small objects that are to be shaped or drilled.

16.  HACKSAWS: It is metal cutting tools , used for parting off or for cutting materials.
A fine toothed blade have 24 to 32 teeth per inch and are used for cutting thin materials where as the coarser blade has 14 to 18 teeth per inch and are for thicker materials. At least  two teeth must be in contact with the work being cut at all times.
=> the pressure should be applied on the forward stroke and relived on the return stroke.  The teeth should must be facing forward.

 17. SHEET METAL SHEAR AND SNIPS: It is used to cut long straight cuts across a piece of metal sheet. Left cutting shears are colored red while right cutting shears are colored green
.
18.  FILES:  It is cutting tools used for removing metal from a surface and are made of high carbon steel.  These are classified by their: i)  length, ii) shape iii) cross section iv)cut and  v) grade.
=> the length of the files are measures 150 mm, 200 mm, 250 mm, 300 mm..
=> files are found in verity of shapes :
   i) Parallel
ii) Tapered
iii) Bellied
=> The various shapes and cross section files are:
i) Hand : Blade is usually parallel in shape and used for general filing.
ii) Round: It is used in association with bellied parallel and tapered blade shape.
iii) Half round: It is associated with bellied shape and used for filing small radii.
iv) Square: It may be bellied , tapered or parallel in shape. They are used for internal work.
v) Three square : These are bellied in shape and used for filing internal corner.
=>The cut of files refers to the arrangement of the cutting teeth. The  common cuts are: 
i) Single cut: It has its teeth cut  parallel in single direction at an angle of 60 degree to the main axes of the blade. 
ii) Double cut:  It has one set of teeth cut an angle of 60 degree and the another one crossing set  cut an angle of 75 degree.
iii) Dreadnought cut:  It is used for heaving cutting on board soft metal surfaces.
iv) Rasp  : The raps are cut with punch while the metal is hot at the time of manufacture.
=> Grade of files refers to the depth  and spacing of the cutting teeth.
i) Bastard : Bastard is coarse grade of the file and has 30 teeth per inch.
ii) Second cut:  This files are finer file and has 40 teeth per inch.
iii) Smooth: It has 50 to 60 teeth per inch and gives off good finishing.

19. HAND BRASS ( HAND DRILL):  It is used to cut accurate circular holes in materials. And used to drill holes up to 6.5 mm or 1/4 inch.

20. TWIST DRILLS: It is used to drill holes in metals and other materials.  On drill up to 12.5 mm diameter the sank is parallel and placed into the jaws of a self connecting chuck. On drill above 12.5 mm the sank is usually tapered of 1:20 . The helical flute formed in the drill body, provides a rake angle for the cutting edge of the drill.  In order that drill will cut properly, the point must be ground to the correct shape. The cutting angle of 59 degree a clearance angle of 12 degree and a web angle of 130 degree.
=>there  are typical for normal metal cutting such as aluminium alloy, cast iron and copper.
=> There are many different grades of metals used:
1. Carbon steel drill : The letter CS may be found on the shanks of the drill. It contain carbon iron with silicon ,phosphorous.
2. High speed steel drill : HSS contain high percentage of tungsten( 8%--12%) with a lesser % of chromium (5%) and smaller amount of vanadium.
3. Cobalt steel : Cobalt steel drill contain up to 12% cobalt with much as 20% tungsten, 4% chromium, 1%--2% vanadium and 0.8% carbon is used. It is very hard  and brittle.
=> The most common methods of identifying the diameter of twist drills are:
1. Metric
2. Fraction of an inch
3. The number/ letter range.
RECOMMENDED LUBRICANTS FOR METALS:
MILD STEEL:  soluble oil
HIGH CARBON AND ALLOY STEEL:  kerosene and turpentine.
ALUMINIUM ALLOYS: kerosene
CAST IRON AND BRASS : Usually no lubricant required.

21. STOP AND PRESS(DIMPLING), COUNTERSINKING:  Two are used during riveting process are stop countersinking bit and the press countersinking or the dimpling tool' these are used for flush skin on high performance aircraft.

22. REAMERS: These are precision ground tools which are used to enlarge drilled holes to accurate dimension and provide smooth internal finished. These are made up of high carbon steel or alloy steel. The three most common types of reamers are:
1. Hand parallel reamer : These are fixed size parallel bodies possessing either straight or spiral flutes.
2. Hand expanding reamer:  These are used where standard parallel reamers of the required dimension are not available.
3. Hand taper reamer :  This  reamer are used to produce a tapered hole for insertion. The two types of taper pin are metric and imperial.
i. Metric:  Its corresponding taper pin have taper of 1:50.
ii. Imperial:   The reamer and the taper pin have a taper of 1:48. 

23. INTERNAL SCREW THREAD CUTTING TAPS : Taps are used for the internal cutting screw thread up to maximum diameter approx. 25.4 mm.  A tap set which all have the same maximum diameter , normally consists of:
i) Taper tap: Used for start the thread cutting process.
ii) Second tap: Used to following the taper tap to depend the thread,
iii) Plug tap : The plug has no taper and its purpose is to finished the thread in deep.
=> To  this end the taper after each full turn is rotated backward approximately 1/2 to 3/4 turn to break the cutting off and keep on forward.

24. EXTERNAL SCREW THREAD, CUTTING DIES : Dies are used for the external (male)cutting of the screw thread. These die are within the stroke. A circular disk called shoulder and adjusting screw are installed in it.

25. SCREW DRIVER:  Screw driver may be divided into two types:
1. BLADE SCREW :  It consists of a high carbon steel or an alloy steel blade. If the blade is high carbon steel. It will be hardened and tempered. These are classified by type and length of the blade which can be approx. 35 mm.
2. CROSS POINT SCREW : This designed by different manufacturer of different
head types, these head types allow greater torque to be applied.
=> there are so many types of screw driver with its selection :
i. Offset screw driver:  Which can reach screw with little clearance above their head .
ii. Reversible Tip screw driver: It allow the sank of screw driver to be reversed  in the handle to provide a different tip, with a blade at one end and across point at the other end of the head.
iii. Interchangeable Tip Screw driver:  Which have a selection of a socket like tips, that can be interchange.

 26. PLIERS:   These are classified by their types and overall length and made up of alloy steel.  These are used for gripping, bending, or moving small items that can not be easily handle by hand.  There are so many types of pliers . some of them are :
i. Side cutting pliers: Used for installation and removal of split pin.
ii. Round nose pliers: Used for putting small radius bend into wire .
iii. Flat nose pliers: Used for many small holding and bending  tasks.
iv. Needle - nose pliers: Which have finely pointed jaws can be used in electrical and electronic work and can be used for holding small wire and electronic components.
v. Wire locking pliers: Used for gripping wire during the wire locking components.
vi. Cir-clips pliers: Which may be found in two external and internal. Used for install and remove cir-clips.

26. WIRE SNIPS ( Nipper) :  It used to cut and stripe wire and to remove split pin.

27. SPANNERS, SOCKETS AND WRENCHES :  The commonest spanner are used on standard hexagonal heads of bolts, nuts,  screw similar shaped fastening device.   Most spanner are manufacture from case hardened mild steel, hardened and tempered high carbon steel, alloy steel though some are made from copper alloy where spark resistance tools are required.
=> Two main sizing system are used :
           I).BRITISH STANDARD AND BRITISH ASSOCIATION: 
=>  BS  system uses imperial units( fraction of an inch). The sizing on BS spanner relates to the nominal diameter nuts, bolts or studs upon which spanner is to be used.  But BA system used imperial unit and although they are in decimal  fraction of inch and are represented by whole number like ( 2 BA, 3 BA etc.)
II).AMERICAN AND METRIC SYSTEM :   The American fine and unified threaded system also used imperial measurement. The sizes stamped on the spanner, refers to the dimensions across the spanner jaws .
=>  Some most common spanners and wrenches are :
i. Set or open jaw spanner : The open jaw are sets an angle of 15 degree. 
ii. Ring spanner: They give full enclosure of the hexagonal head.
iii. Flare nut spanner : Designed with the gap in the ring which allow the spanner to be placed over a pipeline or electrical loom.
iv. Sockets : These are available both in metric and imperial form. 1/4'' square drive and the 3/8'' square drive  are most popular.
=> The main accessories, supplied with socket set are:
a. Richet handle : It allow to continue the turning even if the space does not allow full rotation of the normal 'T' bar driver.
b. Drive bar : It has long handle so used for nuts tightening purpose.
c. Speed braces : They are used turn down  nuts or screw  which have many thread before they tighten up.
d. Extension bar : Used where access for a standard drive handle is restricted found in length 50 mm to 1 m.
e. Universal joints : They are used to tight nuts, screw, bolts etc where it is not possible to obtained access in straight line.
f. Converter or adapters : It allows sockets from one type of drive to be used with another type.
v. Allen key :   Made from hexagonal section, steel bar suitably hardened and tempered and are cranked at 90 degree.
vi. Torque wrenches: It is a precision tool that governs the amount of force applied to a fastener and allows accurate torque values to be applied consistently.
AMOUNT OF TORQUE= FORCE APPLIED x DISTANCE FROM CENTER OF THE FASTENER AND FORCE APPLIED.
=> There are many design for the torque wrenches . The three basic types are :
1. DEFLECTING BEAM : It has a square drive on the one end of an accurately ground beam with a handle mounted on a pivot at the other end.
2. TORSION BAR : It uses the principle of that a bar accurately deflect in torsion as well as bending when force is applied.  When bar is twisted the racks moves across a pinion gear in a dial indicator, which shows the amount of bar deflection.
3. TOGGLE TYPE : It is preset to the desire torque before it is put on a fastener.  An audible click heard when it is reached.
=>TORQUE WRENCH EXTENSION : During maintenance an adapter must be attached to the end of the torque wrench, this will change the overall effective length of the liver mechanism. Hence
 SCALE READING = specified torque x L/ L+A   where L = torque length, A= adapter length.
=> before using torque wrench calibration must be check.

. COMMON POWER TOOLS:

1. ELECTRICALLY POWERED PILLAR MACHINE :  It is used for heavy duty drilling tasks where large drill sizes and rigid. We can change speed of rotation of the chuck to suit the material being drilled and the size of the drill being used.

2. ELECTRICALLY POWERED HAND DRILLS : The smaller electric drill have a 6.5 mm (1/4'') chuck whilst other larger can be found with chuck up to 13 mm(1/2'') and larger.

3.  PNEUMATICALLY POWERED HAND DRILLS:  This is used for a specific tasks depends very much on the access available.   The common  types and uses of pneumatic drill are:
a. Straight drill : Can be used for conventional drilling and uses twist drill with diameter 8 mm.
b. Angled drill :  Available for drilling holes where access is not possible with straight type. Examples offset head drill. Uses twist drill having diameter 4.8 mm.
c. PISTOL GRIP DRILLS : It have standard chuck and key arrangements accept  twisted drill of diameter 8 mm.

4. PNEUMATICALLY POWERED RIVETING HAMMER :  The two  basic types of these hammer may be divided as:
I. SHORT STROKE :  Fast hitting hammer which produce light blows.
II. LONG STROKE HAMMER: Slower hitting hammer which produce light blows.

5. PNEUMATIC MILER ( Micro shaver) :  It is used to flush leaved mandrel of rivet during installation. It has adjustable stop to prevent the cutting tool from damaging the skin.

6. NIBBERS : It is used for rough cutting small to medium sized holes in skin , radio chassis, instrument panel and other light alloys sheets.
7. ABRASIVE WHEELS ( GRINDING WHEELS) :  It is doubled wheel, benched mounted machine. Coarse grinding wheel used for rapid metal removal and a finer  wheel is for smoother work. 
=> The two main types of abrasive  used for grinding wheel are :
1. ALUMINIUM OXIDE OR CADMIUM  :  Used for steel and other ferrous metals of high tensile strength.
2. SILICON CARBIDE:  Its trade name is ' CARBORUNDUM'.  Used for hard and brittle metals such as cast iron  and also used for grinding aluminium, brass, bronze or copper.
=> only authorized personnel  are allow to use abrasive wheel.