Drawing Changes

Change to a design drawing, with the exception of minor clerical corrections, is usually accompanied by a new issue number and date. New parts added to the drawing or ‘drawn on’ parts affected by the change, take a new issue number, and parts which are not affected retain the original issue number. In all cases where interchangeability is affected, a new drawing number and part number are allocated.

Details of the drawing changes are recorded in the appropriate column on the drawing or recorded separately on an ‘Alteration Sheet’, which is referenced on the drawing.

The issue number may be represented by a letter. Some organisations use alphabetical issues for prototype aircraft drawings and numerical issues for production aircraft drawings. Thus all drawings of a prototype aircraft become ‘Issue 1’, when production commences.

An alteration to a single part drawing may also result in changes to associated drawings and may be necessary to halt manufacture or assembly of the product. The Drawing Office system usually makes provision for the proper recording of drawing changes, by publishing concurrently with the re-issued drawing, an instruction detailing the effects these will have on other drawings, work-in-progress and on existing stock.

As a further safeguard, some organisations publish ‘Drawing Master Reference Lists’, which give details of the current issues of all drawings which are associated with a particular component or assembly.