The task of designing test equipment can be as complicated as the system it is to test and should begin early and be coordinated closely with the work of the system/subsystem design.
Instrumentation shall be built into the test installation, be highly reliable, reproduce results, be at least an order of magnitude (X10) more accurate than the system and comprising equipment tolerances.
This high order of accuracy is necessary to ensure precise working of the system equipment.
Test tolerance analysis shall be performed to verify compliance; using the system, Test Equipment Calibration, and Acceptance Test tolerances.
In-process inspections and testing
Inspection and testing of the technical system and
its comprising configuration items shall be performed during development,
production, and maintenance phases of the system life cycle.
Control of inspection, measuring, and test
equipment.
Inspection and test equipment shall be designed to meet the test requirements of the system and its component items. Any measurement capability needed and not identified shall be identified.
Calibration of inspection and test equipment shall not adversely affect confidence in the accuracy of the equipment.
During design the cumulative effect of errors in each successive component of a calibration chain shall be taken into account for each piece of test equipment (tolerance tiering).
A record of the tolerance analysis for each inspection and test equipment shall be prepared and maintained with the calibration record. The basis for the calibration shall be recorded.
Calibration intervals shall be established on the
basis of stability, purpose, and usage. Intervals of calibration
may vary dependent on the results of previous calibrations.
Tolerance tiering.
The Performance specifications (requirements) shall contain requirements in absolute terms with the require accuracy.
Other components or items shall be specified in requirements
specifications (development and product). Qualification of these
requirements shall be stated in indicated values which must be
absolute minus the (measurement) test/inspection equipment uncertainty.
e.g.,
Indicated Value <= Absolute - Measurement Uncertainty
A record for each requirements qualification shall be kept.
Measurement Uncertainty shall be obtained from the
Calibration values and equipment instabilities (environmental,
etc.)
To be continued.
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