Types of Drawing

There are four main types of drawings recommended by the BSI, although there are many other types and sub-types are used at different times.

The main drawing types are the:

• Single-part: unique parts or assemblies
• Collective: parts or assemblies of similar shape, but of different dimensions
• Combined: complete assemblies including all individual parts on a single drawing
• Constructional: assembly drawing with sufficient dimensional and other information to describe the component parts of a construction.

A complete set of drawings for an aircraft and any documents or specifications referenced on the drawings, represents a complete record of the information required to manufacture and assemble that aircraft. The manner in which a set of aircraft drawings is arranged, enables any particular component, material, dimension, procedure or operation to be traced.

Drawings of individual parts contain all the necessary information to enable the parts to be manufactured to design requirements. The material specification, dimensions and tolerances, machining details and surface finish and other requirement treatment would all be specified on the drawings.

Sub-assembly drawings are issued to convey specific information on the assembly of component parts. When the method of assembly involves welding or a similar process, the drawing will include details of any heat treatment or anticorrosive treatment that may be necessary. Sub-assembly drawings are sometimes issued in connection with spares provisioning and also in instances where assembly would be difficult without special tools, jigs or techniques.

Installation drawings are issued to clarify the details of external dimensions and attitudes of components, locations, adjustments, clearances, settings, connections, adapters and locking methods between components and assemblies.

A main General Arrangement (GA) drawing of the aircraft and GA drawings of main assemblies are also provided. These drawings usually contain overall profile particulars only, with locations and references of the associated main assembly and installation drawings. They also provide a guide to the identification of drawing groups used by the particular design organisation.

Main assembly drawings may also contain profile particulars only, but will include the information required for the assembly of individual parts of sub-assemblies. The sequence of assembly is given where appropriate, but the information contained in single-part or sub-assembly drawings is not repeated. In case of sub-assemblies, only the sub-assembly will be referenced and not its individual parts.

There are a number of other drawings, which are used to display alternative views of a component or to show where that component appears in a system, while pictorial diagrams or charts are used to show complete or part representations of functional systems such as hydraulic and electrical systems.