Quality assurance

Quality Assurance By Brian Whitehead March 1999 Brian Whitehead is chief, policy development for the Aircraft Maintenance & Manufacturing branch in Ottawa. E-mail questions or comments to whitehb@tc.gc.ca. Procedures to ensure that...


Quality Assurance

By Brian Whitehead

March 1999

Brian Whitehead

Procedures to ensure that maintenance tasks are completed correctly, have been an integral part of organized maintenance activities for many years.

When civil aviation activity recommenced following WWII, the larger maintenance operations typically assigned selected members of their technical staff to inspect and release the work performed by the production team. Variations of this technique are still with us today, the most common example being the Required Inspection Items (RII) of FAR 121. This process of examining a finished product for compliance is generally referred to as Quality Control (QC).

In recent years, with the growing complexity of aircraft systems and enhanced insight into the psychological and physiological aspects of maintenance (the "human factors"), it has become clear that quality control alone is not enough. For one thing, many processes are susceptible to errors that are difficult, if not impossible, to find by direct inspection. Computer programming, composite repair, and welding are good examples of this. Also, the very knowledge that an inspection will be done, and that the inspector will assume responsibility for the work, can in some cases lead to a sense of complacency that defeats the object.

Even without these problems, the rejection of work in its final stages is an inefficient and expensive way to ensure quality. All these factors have lead to the increasing use of a more comprehensive approach, generally referred to as Quality Assurance (QA). The Continuing Analysis and Surveillance system required by FAR 121 is one example of a QA application.

For the purposes of this article, QA can be considered to be the sum of all actions taken to provide assurance that the desired outputs will be attained. Instead of concentrating on the finished product, QA takes into account all aspects of a process, from planning to completion, and identifies weak points that could be prone to the introduction of errors. While inspection of the final product remains an essential part of the QA process, there are three significant differences between this and a QC final inspection.

First, the primary purpose is not to find defects per se (although, of course, if faulty items are found, they will be rejected). Rather, the finished product is inspected as one means of confirming the satisfactory operation of the system as a whole. Secondly, the QA inspector does not sign the release for the work. I will return to this point later. Finally, QA inspections are generally done by sampling, rather than looking at 100 percent of the items involved.

Unlike the U.S. FARs, the Canadian Aviation Regulations (CARs) do not require Air Operators or Approved Maintenance Organizations (AMOs) to have a QC system. There are several reasons for this, the primary one being that, under the Canadian system, every maintenance task can be considered an RII, as each is subject to a maintenance release, and the person signing that release assumes full responsibility. The fact that only a representative sample of each task is subject to QA inspection further underlines the AMEs' responsibilities, as they will be aware that, most of the time, theirs is the final inspection.

Both Air Operators and AMOs however, must have a QA system. In the case of the Air Operator, the system is required by 706.07 Evaluation Program. For an AMO, the system is required by 573.09 Quality Assurance Program. It is the latter system that I refer to here.

An AMO's QA system must be independent of all aspects of production. That is, the persons involved in QA must have no involvement in the planning, performance, recording, or certifying of the work inspected. Isolating QA personnel from responsibility for the items they inspect avoids any potential conflict of interest, and emphasizes the fact that the inspection is centered upon the performance of the system as a whole, not merely on its results. QA inspectors are simply critics, who identify existing or potential defects, and bring them to the attention of the parties responsible.

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