Drawings must give such 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, and any other information essential to making and assembling the particular object.
Drawings may be divided into three classes: (1) detail, (2) assembly, and (3) installation. [Figure 2-3]
A detail drawing is a description of a single part, describing by lines, notes, and symbols the specifications for size, shape, material, and methods of manufacture to be used in making the part. Detail drawings are usually rather simple; and, when single parts are small, several detail drawings may be shown on the same sheet or print. (See detail drawing at the top of Figure 2-3.)
An assembly drawing is a description of an object made up of two or more parts. Examine the assembly drawing in the center of Figure 2-3. It describes the object by stating, in a general way, size and shape. Its primary purpose is to show the relationship of the various parts. An assembly drawing is usually more complex than a detail drawing, and is often accompanied by detail drawings of various parts.
An installation drawing is one which includes all necessary information for a part or an assembly in the final installed position in the aircraft. It shows the dimensions necessary for the location of specific parts with relation to the other parts and reference dimensions that are helpful in later work in the shop. (See installation drawing at the bottom of Figure 2-3.)
Sectional View Drawings
A section or sectional view is obtained by cutting away part of an object to show the shape and construction at the cutting plane. The part or parts cut away are shown by the use of section (crosshatching) lines. Types of sections are described in the following paragraphs.
A full section view is used when the interior construction or hidden features of an object cannot be shown clearly by exterior views. For example, Figure 2-4, a sectional view of a coaxial cable connector, shows the internal construction of the connector.
In a half section, the cutting plane extends only halfway across the object, leaving the other half of the object as an exterior view.
Half sections are used to advantage with symmetrical objects to show both the interior and exterior.
Figure 2-5 is a half sectional view of a quick disconnect used in aircraft fluid systems.
A revolved section drawn directly on the exterior view shows the shape of the cross section of a part, such as the spoke of a wheel. An example of a revolved section is shown in Figure 2-6.
A removed section illustrates particular parts of an object. It is drawn like revolved sections, except it is placed at one side and, to bring out pertinent details, often drawn to a larger scale than the view on which it is indicated.
Figure 2-7 is an illustration of removed sections. Section A-A shows the cross-sectional shape of the object at cutting plane line A-A. Section B-B shows the cross-sectional shape at cutting plane line B-B.
These sectional views are drawn to the same scale as the principal view. Note that they are often drawn to a larger scale to bring out pertinent details.