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The Main Rotor Bifilar Absorber and Its Effect on Helicopter Reliability/Maintainability
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English
Abstract
The requirements of higher aircraft availability, lower maintenance costs, and a more comfortable passenger/crew environment demand low vibration in helicopters. To meet this objective, Sikorsky Aircraft has developed and reduced to practice the main rotor head bifilar absorber. The bifilar absorber reduces vibration directly at the source-the main rotor. It cancels the rotor system exciting forces before they are transmitted into the airframe, and thus effectively controls vibration throughout the helicopter. Reduced vibration levels translate directly into improved reliability and maintainability.
The principle of the bifilar absorber and the vibration reductions achieved in production installations are described. The quantitative improvement in reliability and reduction in maintenance resulting from the reduction in vibration are presented. The field data were collected from 15 aircraft without the bifilar absorber and from 15 aircraft with the bifilar absorber. The data show a 40% reduction in maintenance resulting from a 55% average vibration reduction.
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Citation
Wachs, M., "The Main Rotor Bifilar Absorber and Its Effect on Helicopter Reliability/Maintainability," SAE Technical Paper 730894, 1973, https://doi.org/10.4271/730894.Also In
References
- Veca A. “Vibration Effects on Helicopter Reliability and Maintainability.” USAAMRDL Technical Report 73-11 1973
- Den Hartog J. P. “Mechanical Vibrations.” New York McGraw-Hill Book Co., Inc. Fourth 1959 219 222
- Paul W. F. “Development and Evaluation of the Main Rotor Bifilar Absorber.” Proceedings of 25th Annual AHS Forum May 1969
- Yamakawa G. M. et al. “Attack Helicopter Evaluation, Blackhawk S-67 Helicopter.” Final Report U. S. Army Aviation Systems Test Activity Edwards Air Force Base, Calif. 93523 July 1972
- Department of the Air Force “Maintenance Management Manual AFM 66-1.” Headquarters, USAF, Washington, D.C. February 10 1970
- Blanchard Lowery “Maintainability Principles and Practices.” New York McGraw-Hill Book Co., Inc. 1969