This document provides information about aircraft drawings, including: 1. It describes different types of drawings like detail drawings, assembly drawings, and installation drawings that provide information about individual parts, assembled objects, and part locations. 2. It discusses drafting techniques used in drawings like orthographic projections, sectional views, title blocks, dimensions, tolerances, and pictorial views. 3. It explains various drawing annotations used to identify parts, revisions, materials, and locations on aircraft like reference numbers, zone numbers, station numbers, and butt lines.

1. AIRCRAFT DRAWINGS
BY
MANI RATHINAM RAJAMANI

2. DRAWINGS
• Drawing :
– A method of conveying ideas concerning the construction / assembly of
objects.
– Link b/w Designer and Assembler
– Described by lines, notes, abbreviations, symbols ,..ETC.
• Modern Drawings:
– Computer Aided Design Drafting (CADD)
– Computer Aided Design (CAD) : Product Design.
– Computer Aided Manufacturing (CAM) : Product Manufacturing.
– Computer Aided Engineering (CAE) : Product Engineering / Analysis /
Simulation & PLC.

3. Do’s & Dont’s
• Care and Use of Drawings :
– Drawings are both expensive and valuable.
– Handle with Care.
– Do smooth out the fold lines instead of bending back.
– lay them on a flat surface.
– Hands free of oil, grease, etc. that soil / smudge prints.
– Never make notes or marks on a print to avoid confusions.
– Authorized personnel changes Only permitted with sign and date any
changes they make.

4. DRAWING TYPES
• Information as size and shape of the object and all of its parts,
• Specifications for material to be used,
• how the material is to be finished,
• how the parts are to be assembled,
• Types of Drawings:
– (1) Detail,
– (2) Assembly,
– (3) Installation.

5. DRAWING TYPES
• DETAIL DRAWING:
– A description of a single part,
– described by lines, notes, and symbols the
specifications for size, shape, material, and
methods of manufacture.
– several detail drawings may be shown on the
same sheet or print.
• ASSEMBLY DRAWING:
– A description of an object made up of two or
more parts.
– to show the relationship of the various parts
assembled.
– An assembly drawing is usually more complex
than detail drawing and accompanied by detail
drawings.

6. DRAWING TYPES
• INSTALLATION DRAWING :
– all necessary info for a part or an
assembly in the final installed
position in the aircraft.
– shows dimensions necessary for
location of parts with relation to
the other parts
– reference dimensions that are
helpful in later work in the shop.

7. SECTIONAL VIEW DRAWINGS
• Section / Sectional view is obtained by cutting away part of an object to
show the shape and construction at the cutting plane.
• Parts cut away are shown by use of section (crosshatching) lines.
• Types of sections are.
– Full Section
– Half Section
– Revolved Section
– Removed Section

8. SECTIONAL VIEW TYPES
• FULL SECTION :
– used when interior construction or hidden
features of an object cannot be shown
clearly by exterior views.
• HALF SECTION :
– the cutting plane extends only halfway
across the object,
– leaving the other half of the object as an
exterior view.
– used to advantage with symmetrical objects
to show both the interior and exterior.

9. SECTIONAL VIEW TYPES
• REVOLVED SECTION
– drawn directly on exterior view
– shows the shape of the cross
section of a part.
• REMOVED SECTION
– Illustrates particular parts of an
object.
– drawn like revolved sections,
– placed at one side.
– to bring out pertinent details.
– often drawn to a larger scale than
view indicated.

10. TITLE BLOCK
• TITLE BLOCKS:
– means of identification.
– consists of data concerning the
drawing
1. A drawing number.
2. The name of Part or Assembly.
3. Scale.
4. Date of Release.
5. Name of firm.
6. Name of draftsmen, checker, and
the approver.
– Position: lower right-hand corner.

11. DRAWING NUMBER
• Drawing or Print Numbers:
• All prints are identified by a number
• appears in a number block in lower right-hand corner of title block.
• may be also shown in other places
– near the top border line,
– in the upper right-hand corner,
– on the reverse side of the print at both ends.
• Purpose : quick identification of a print.
• sheet number and number of sheets in series.

12. REFERENCE AND DASH NUMBERS
• Ref No’s appear in title blocks
• refers to numbers of other prints.
• When more than one detail is shown, Dash numbers are used.
• Both parts would have same drawing number with an individual dash
number.
• Also appear on face of drawing near parts they identify.
• Also used to identify right-hand and left-hand parts which are mirror
images.
• Thumb rule : odd numbers for left-hand parts and even numbers for right-
hand parts.

13. BILL OF MATERIAL (BOM)
• A list of materials and parts necessary for fabrication / assembly of a
component / system.
• usually in ruled columns in which are listed
– Part number,
– name of the part,
– material from which part is to be made,
– quantity required,
– Source of part or material.
• On assembly drawings, each item is identified by a number in a circle or
square.
• An arrow connecting number with item assists in locating it in bill of
material.

14. OTHER DRAWING DATA
• REVISION BLOCK:
• Revisions are necessitated by changes in
dimensions, design, or materials.
• changes are listed in ruled columns
– either adjacent to the title block
– or at one corner of the drawing.
• All changes must be carefully noted on
all existing prints of drawing.
• When drawings contain such corrections,
attention is directed to changes by
lettering or numbering them.
• Changes are listed against a symbol in a
revision block.
REVISION BLOCK contains:
• identification symbol,
• Revised dates
• nature of revision
• Authority Name for
change
• Name of draftsman who
made change.

15. OTHER DRAWING DATA
• NOTES:
• refer to methods / alternate applicable methods of attachment or
construction.
• used only when information cannot be conveyed in conventional manner
• Used to avoid crowding the drawing.
• When the note refers to a specific part, a light line with an arrowhead leads
from the note to the part.
• If it applies to more than one part, note is worded to eliminate ambiguity as
to the parts to which it pertains.
• If there are several notes, they are generally grouped together and
numbered consecutively.

16. OTHER DRAWING DATA
• ZONE NUMBERS:
– are similar to numbers and letters printed on borders of a map.
– Help to locate a particular point.
– To find a point, mentally draw horizontal and vertical lines from the
letters and numerals specified;
– point where these lines intersect is the area sought.
– Used to locate parts, sections, and views on large drawings, particularly
assembly drawings.
– Parts numbered can be located on drawings by finding numbers in
squares along the lower border.
– Zone numbers read from right to left.

17. OTHER DRAWING DATA
• Finish Marks :
– used to indicate surface finish required
– better appearance and allow a closer fit with adjoining parts.
– Standard limits and tolerances must be observed.
– Do not confuse machined finishes with paint, enamel, chromium
plating.
• Scale :
• exactly same size as drawn part; a scale of 1:1.
• Application:
• When shown near title block, application may refer to aircraft, assembly,
sub-assembly or next installation on which part would be used.

18. LOCATION IDENTIFICATION
• STATION NUMBERS :
– A numbering system is used on large assemblies for aircraft to locate stations
such as fuselage stations.
– Fuselage station value indicates a location value of inches from the datum of
the aircraft.
– Measurement is taken from nose or zero station or A point chosen by
manufacturer.
– Fuselage stations (FS), Wing stations (WS), Stabilizer Stations (SS).
• Measurement taken from centerline / zero station / ground level of aircraft.

19. LOCATION IDENTIFICATION
• WATERLINE :
– Vertical locations on an airplane are made in reference to the waterline.

20. LOCATION IDENTIFICATION
• BUTT LINES:
– locations left and right of
aircraft’s longitudinal axis
– Locations made by reference to
buttock line / butt stations.
– Left Buttock Line (LBL) and
Right Butt Line (RBL).

21. TOLERANCES & ALLOWANCES
• TOLERANCE:
– a given dimension with an allowable variation,
– plus (+) indicates maximum, and minus (−) minimum allowable variation.
– sum of plus and minus allowance figures is called tolerance.
– If the plus and minus allowances are the same, presented as value ± tolerance.
• ALLOWANCE:
– indicated in either fractional or decimal form.
– Used for very accurate dimensions,
– decimal allowances are used.
– Fractional allowances are sufficient when precise tolerances are not required.
– Standard tolerances may be given in title block to apply throughout drawing.

22. METHODS OF ILLUSTRATION
• DRAWINGS:
– Orthographic Projection Drawings
– Detail View
– Pictorial Drawings
– Perspective Drawings..
– Isometric Drawings
– Oblique Drawings
– Exploded View Drawings

23. ORTHOGRAPHIC PROJECTION
DRAWINGS
• six possible views of an object.
• front, top, bottom, rear, right side, and left
side.
• One-, two-, and three-view drawings.
• ONE VIEW DRAWINGS:
– One-view drawings : commonly used for
objects of uniform thickness such as
gaskets, shims, and plates.
– used for cylindrical, spherical, or square
parts if all dimensions shown in one
view.
• TWO VIEW DRAWINGS:
– When space is limited and two views
must be shown,
– symmetrical objects are often
represented by half views.

24. DETAIL VIEW
• shows only a part of object but in greater
detail.
• shows to a larger scale than the principal
view.
• parts shown in detail on drawing is
encircled by a heavy line on principal view.

25. PICTORIAL DRAWINGS
• is similar to a photograph.
• shows an object as it appears to the eye.
• useful in showing general appearance of an object
• used extensively with orthographic projection drawings.
• used in maintenance, overhaul, and part numbers.
• Three types of pictorial drawings are used
1. Perspective,
2. Isometric,
3. Oblique,
4. Exploded View drawings.

26. PICTORIAL DRAWINGS
• Perspective Drawings:
– shows an object as it appears to an observer.
– Resembles an object as in a photograph.
– lines of an object are not parallel
– actual angles and dimensions are not accurate.
• Isometric Drawings:
– uses a combination of views of an orthographic
projection
– Tilts the object forward so that portions of all three views
can be seen in one view.
– provides the observer with a three-dimensional view of
the object.
– lines in an isometric drawing are parallel
– dimensioned as they are in an orthographic projection.

27. PICTORIAL DRAWINGS
• Oblique Drawings
– similar to an isometric view.
– except for one distinct difference.
– Two of three drawing axes are always at
right angles to each other.
• Exploded View Drawings
– a pictorial drawing of two or more parts that
fit together as an assembly.
– View shows individual parts and their
relative position to other parts before they
are assembled.

28. DIAGRAMS
• a graphic representation of an assembly /
system
• indicates various parts and expresses
methods or principles of operation.
• Four Types of diagrams
1. installation,
2. schematic,
3. block,
4. wiring diagrams.

29. INSTALLATION DRAWINGS
• a diagram of installation of the flight
components of an aircraft.
• Identifies each of the components in the
systems and shows their location in the
aircraft.
• used extensively in aircraft maintenance
and repair manuals,
• Are invaluable in identifying and locating
components and understanding the
operation of various systems.

30. SCHEMATIC DIAGRAMS
• do not indicate the location of
individual components in the aircraft,
• Used to locate components with respect
to each other within the system.
• used mainly in troubleshooting.
• each line is coded for ease of reading
and tracing the flow.
• Each component is identified by name,
and its location within the system
• Line notes indicate in and out flow of
the unit.
• used extensively in aircraft manuals.

31. BLOCK DIAGRAMS
• used to show a simplified relationship of a
more complex system of components.
• Individual components are drawn as a
rectangle (block) with lines connecting it to
other components (blocks) that it interfaces
with during operation.

32. WIRING DIAGRAMS
• shows electrical wiring and circuitry,
• coded for identification, of all the electrical
appliances and devices used on aircraft.
• Complicated structure.
• Thorough knowledge of wiring and electrical
schematics is essential.

33. FLOWCHARTS
• used to illustrate a particular sequence, or flow of events.
• Types are
– Troubleshooting Flowchart:
• used for detection of faulty components.
• consist of a series of yes or no questions.
• If yes, one course of action is followed.
• If no, a different course of action is followed.
• a logical solution to a particular problem may be achieved.
– Logic Flowchart
• analysis of digitally controlled components and systems.
• uses standardized symbols to indicate specific types of logic gates
• relationship to other digital devices in a system.
• consist of individual components that take an input
• and provide an output.
• By analyzing inputs, it is possible to determine digital output.

34. LINES AND THEIR MEANINGS
• Lines mark boundaries, edges, and
intersection of surfaces.
• used to show dimensions and hidden
surfaces and to indicate centers.
• Types:
– Centerlines
– Dimension Line.
– Extension Lines.
– Sectioning Lines.
– Phantom Lines.
– Break Lines.
– Leader Lines.
– Hidden Lines.
– Outline / Visible Lines
– Stitch Lines.
– Cutting Plane and Viewing
Plane Lines.

35. LINES AND THEIR MEANINGS

36. DRAWING SYMBOLS
• represent shape and material.
• short hands of drawing.
• graphically portray characteristics
of a component with a minimal
amount of drawing space.
• Types:
– Material Symbols
– Shape Symbols
– Electrical Symbols

37. INTERPRETING DRAWINGS
• read drawing number and description.
• check model affected, latest change
letter, the next assembly listed.
• read illustrations.
• For multi-view drawing,
• get a general idea of shape of object
• select one view for a more careful
study.
• referring back and forth to adjacent
view.

38. GRAPHS & CHARTS
• Frequently used to convey
information graphically.
• Projection of values on x-y axes.
• all notes and legends be carefully
understood in order.
• Types of Graphs used:
– Nomograms:
• a graph of three sets of data.
• Input of any two sets of data
enables interpreter to obtain
value for third unknown.

39. QUESTIONS>?

40. THANK YOU