Cockpit Voice Recorder CVR Configuration z Unused channel
- Slides: 11
Cockpit Voice Recorder (CVR) Configuration z. Unused channel acts as vibration transducer
The Triboelectric Effect Outer Shield + ++ ++ -- -- + - Insulator Inner Conductor Outer Jacket Frictional forces generated at the boundary between the inner conductor and outer shield due to cable vibration strips off free electrons, creating time dependent current that can be measured.
Demonstration of Triboelectric Effect Twisted pair wire forming an open-circuit with one end connected to an oscilloscope - Wire vibration excited by running thumb-nail over twisted-wire outer insulation.
Jet Turbine Signals from CVR Silent Track Generated by Triboelectric Effect
Example of Health Monitoring Signature Red spikes indicator of engine-truss damage
Laboratory Test Subject: Star. Lite Aircraft
Current Testing z. Mount twisted pair wires on Star. Lite fuselage z. Use signal analyzer to obtain data z. Take data while tapping aircraft with instrumented hammer z. Take data while shaking aircraft to impose background noise level
Impulse Hammer Tests by Impacting Engine-Truss Joint Impulse Hammer Test Wire
Impact Hammer Response of Twisted Pair Wire Undisturbed Aircraft Impact Signature Wire Response
Impact Hammer Response of Twisted Pair Wire Aircraft Undergoing Random Vibrations Impact Signature Wire Response
Conclusions z Impacts induce significant voltages in twisted pair wire z Impact output is visible above background noise y. Electrical noise y. Aircraft vibration z Wire amplitude and phase responses are very flat over frequency bandwidth from 600 Hz to 6 k. Hz
