CVM™ Product Overview
CVM™ technology uses the principle that a vacuum maintained within a small volume is extremely sensitive to leakage. Essentially the CVM™ technology provides a measure of the differential pressure between alternating channels containing air at a partial vacuum pressure and channels containing air at atmospheric channels in a simple manifold.
These channels are on the under surface of a sensor that is applied to a surface on a critical structure that requires monitoring. If a crack begins to develop underneath the sensor, air will flow from the channels at atmospheric pressure, through the passage created by the crack, to the vacuum channels. A transducer is used to measure the air flow between the channels and provide feedback to the software management system, which in turn reports on the development of the crack. The sensitivity of the sensor is governed by the gallery spacing and the rate of air flow gives an indication of the size of the developing flaw.
SMS has conducted extensive research to prove the principle of the technology and has developed a number of sensor types and associated testing systems. To date the current CVM™ system consists of the following four main components:
A sensor that is applied to the area requiring testing or inspection
A vacuum source to control and apply a partial vacuum to the sensor
A differential pressure flow meter device with output options that interface with the control systems and
Software management systems that process the data
The existing generation of the technology is suitable for static or periodic monitoring (for grounded aircraft). To create an in-flight continuous monitoring system SMS will need to create a host of new sensor technologies and in-flight instrumentation.