Critical Item

Items are critical if they have a major impact on the realization
and use of the product. Items are critical if they have a significant
effect on the safety, performance, form, fit, function, producibility,
or service life of the product. Critical items require specific actions
to ensure that they are adequately managed.

Examples of critical items include key characteristics, parts,
functions, processes, and software. They include mission
critical items, safety critical items, and fracture critical items.

Key Characteristic

A key characteristic is a feature or attribute that has a significant
impact when it varies. Whenever a key characteristic varies, it has an
important effect on the performance, form, fit, function, producibility,
or service life of the product. Therefore, key characteristic variations
must be controlled.

Risk

A risk is an undesirable situation or circumstance that has
two characteristics: it is both likely to occur and likely to cause
negative consequences.

The concept of risk is always future oriented. It worries about
the impact that undesirable circumstances or situations could
have in the future.

Special Requirement

A special requirement is a requirement that may be especially difficult
to achieve. Special requirements may be difficult to achieve because
they force you to operate at the limit of your organization’s technical
or process capability or at the limit of your industry’s capability.

Either you or your customer may decide that a requirement is special.
In order to figure out whether or not a requirement is special, consider
the complexity and maturity of your product or process and your
organization’s past experience.

Since there is a risk that your organization may not be  able to
meet a special requirement, you’re expected to include it in your
risk management process.

NOTE: Critical items, special requirements, and key characteristics are new
interrelated concepts. Special requirements force you to operate at or near
the limit of your organization’s capability. Therefore, they tend to be difficult
to achieve. In order to meet these difficult requirements you may need to
carefully manage critical items. And if such items tend to vary, you may
also need to treat them as key characteristics in order to control them.

Additional Quality Management Definitions

Introduction to AS9100C Standard

Overview of Quality Management Standard

AS9100C Standard Translated into Plain English

How to Upgrade to the new AS9100C:2009 Standard

Aerospace Quality Management Gap Analysis Tool

Aerospace Quality Management Audit Program