The means by which verification is accomplished will
depend on the maintainability characteristic or data element to be verified.
For qualitative elements, such as accessibility, clearances for use of tools,
available work space, or safety concerns, ease of maintenance studies can be
planned and executed. This may include the use of mock-ups, or in the future,
the use of virtual mock-ups using virtual reality techniques as discussed in
4 of this handbook. Other verification methods include design reviews, other special studies (e.g., maintenance task analysis or simulation studies), or review of historical information on like systems. The verification process should be continuous throughout the system
life cycle, and therefore data obtained from maintainability demonstration testing (see Section 3 of this appendix) and operational test and evaluation should also be used to verify both quantitative and qualitative features.
The process of executing a verification program should follow the general procedural elements outlined below:
- Identify possible data sources and develop data collection and analysis plan
- Evaluate both qualitative and quantitative data
- Compare results with requirements
Quantitative data analysis typically relates to collecting information on maintenance task times, such as removal and replacement times, and developing an approach to statistically compare actual data to predicted values1.
1See Downs, W.R., "System Maintainability Verification -The Paired Time Comparison (PTC)
Method," Proceedings, 1979 Annual Reliability and Maintainability Symposium for an example of a method used for verification.