Inspection of Non‐Metallic Materials

THE main working documents for an inspector are specifications and drawings. Among criticisms made at the Natural Rubber Producers' Research Association symposium last year, was that there are too many specifications and I think most of us would agree. However, I think we could improve this situation considerably as far as materials are concerned, if we accepted and really worked in accordance with the fundamental principle laid down in Av.P.970 Chap. 400. This can be summarised as: ‘Specifications for critical materials need approval by D.Mat/Aviation — non‐critical materials do not need such approval’. A rider is added to the effect that non‐critical materials do not need to be inspected to such tightly drawn specifications as critical materials and in some instances commercial quality materials may be used. If one can decide therefore, which materials are critical and which are not, and this is by no means easy, we can simplify inspection procedures and possibly reduce the number of specifications. Obviously critical applications will always call for special quality specifications but it is wasteful to use such materials where they are not necessary. One docs, however, notice a tendency among specification writers to over specify and to classify specifications too highly, i.e. to seek special approval when it is not necessary. It is our view that A.I.D. supervision should be concentrated on critical materials and components and that comparatively little effort should be devoted to non‐critical items, this being left to the purchaser who would probably order standard engineering materials or even commercial quality.