Israni, Mohan G. (1992, ASQC) New York City Transit Authority, New York, NY
Preventative maintenance does not always create 100% operability. In cases where it doesn't, a quality improvement plan must address the repair process to ensure an improvement in equipment reliability, improvement in maintainer productivity, and reduction in cost of quality.
In this scenario, reliability is measured by mean time between failures (MTBF) and productivity by mean time of repair (MTTR). The applicable parameters to be measured include equipment, maintainer, shop, and defect. This defines Parametrical Quality Control.
The process requires Characteristical Quality Control which examines defect identification (based on the defect itself cross-correlated with the failure mode -- vendor supply, repair workmanship, or equipment design/manufacturing quality). CQC also assesses quality costs as they deviate from the plan. CQC follows the Pareto principle in identifying the vital few.The plan sets quality criteria: parametric criteria are set at one sigma better than population mean, CQC are based on fixed standards set by the equipment manufacturer. It also includes corrective action via process correction and vendor/product correction.Since quality is the reason for being of quality control, plans should be in place both to prevent failures and to correct them in an efficient and quality-oriented way.
Quality control (QC),Reliability,Cost of quality (COQ),Preventive maintenance,Parameters,Parametric models,Productivity