Downloaded from https://www.everyspec.com ADS-79D-HDBK (Copies of these documents are available from sources as noted.) E.3 TECHNICAL GUIDANCE The sensor specifications should be appropriate for the amplitude and frequency domain of the component being monitored. These specifications include its bandwidth, dynamic range, and sensitivity. With regard to signal processing, the system‘s sampling rate should be high enough to avoid aliasing which causes a distortion that can mask or alter a feature signature. If these parameters are not carefully matched to the component of interest, the algorithms which detect and identify the fault will not perform to the required specifications.
The detection and identification algorithms themselves should be inexpensive to implement, explainable in physical terms, and be insensitive to extraneous inputs. E.3.1 Sensor guidance. The characteristics of analog sensors include sensitivity, dynamic range, linearity, drift, and bandwidth (or useful frequency range). The following guidance is provided for sensors in a Vibration Monitoring System (VMS). E.3.1.1 Sensitivity. Vibration sensors (accelerometers and velocimeters) should be sensitive enough to measure the smallest amplitude signal generated by an incipient fault at the threshold of detection by the diagnostic algorithm.
The sensor should be able to detect this signal at the specified 101 OTHER Bracewell, R.M. The Fourier Transform and its Applications. McGraw-Hill, 1965. CAP 753 ―Helicopter Vibration Health Monitoring‖ UK Civil Aviation Authority, Safety Regulation Group. August 2012. http://www.caa.co.uk deSilva, Clarence Control Sensors and Actuators, Prentice Hall, NJ, 1989. Keller, J.A., R. Branhof, D. Dunaway, and P. Grabill. Examples of Condition Based Maintenance with the Vibration Management Enhancement Program. Presented at the American Helicopter Society 61st Annual Forum, Grapevine, TX. 1-3 June 2005. McFadden, P.D.
Analysis of the Vibration of the Input Bevel Pinion in RAN Wessex Helicopter Main Rotor Gearbox WAK143 Prior to Failure. Aero Propulsion Report 169, Department of Defense, Defense Science and Technology Organization, Aeronautical Research Laboratories. September 1985. http://oai.dtic.mil/oai/oai?verb=get Record&metadataPrefix= html&identifier=ADA173851 Ogata, K. Discrete-Time Control Systems. Prentice Hall: Englewood Cliffs, NJ, 1987. Roemer, M., J. Dzakowic, R. Orsagh, C. ―Validation and Verification of Prognostic and Health Byington, and G. Vachtsevanos. Management Technologies.‖ IEEEAC paper #1344. 27 October 2004.
http://standards.ieee.org/findstds/standard/1344-1995.html http://standards.ieee.org/findstds/standard/C37.118-2005.html Zakrajsek, J.; P. Dempsey, E. Huff, H. Decker, M. Augustin, R. Safa-Bakhsh, A. Duke, and P. Grabill. Rotorcraft Health Management Issues and Challenges. NASA/TM- 2006-214022. February 2006. http://ntrs.nasa.gov/archive/nasa/casi.ntrs. nasa.gov/20060008910 2006008033.pdf _