N112-118 TITLE: Innovative Method for Real-Time Damage Alleviation

TECHNOLOGY AREAS: Air Platform, Sensors

ACQUISITION PROGRAM: PMA-261, H-53 Heavy Lift Helicopters

OBJECTIVE: Develop a tool to adjust rotorcraft flight characteristics to mitigate damage levels on dynamic rotorcraft components.

DESCRIPTION: State-of-the-art structural health and usage monitoring systems (HUMS) provide the diagnostic and prognostic information used in scheduling maintenance actions. The ultimate advantage of this technology is the ability to reduce the cost and efforts associated with that effort. For example, parts are replaced only as needed based on the outputs from that tool. Additionally, potentially unsafe loadings on components are immediately identified. Using this information to make the proper adjustments to flight characteristics could alleviate or even prevent damage to vital aircraft components. However, no means currently exists to provide HUMS information to the control system or for it to make the necessary adjustments in flight control laws. Having this capability would have a significantly positive impact on mission readiness and substantially reduce repair and replacement costs.

Techniques have been devised that accurately model the dynamics of the rotorcraft under various flight conditions. As such, these tools can provide estimates of the loading sustained by dynamic components for use in fatigue analyses. In addition, algorithms have been generated that estimate loads in the rotating frame by using fixed frame measurements. This information is then used to make a real-time estimate regarding the remaining life expectancy of structural components for maintenance planning.

Advancements in fly-by-wire systems afford an excellent opportunity to integrate cutting-edge HUMS, modeling, algorithm, and sensor technology to enable the control system both to perceive when damage is occurring and to make the necessary adjustments to alleviate the severity in real time. The objective of this SBIR effort is to develop a means to achieve that functionality, which also must work in the background without direct involvement of the flight crew. The solution must not negatively affect the maneuverability, flight quality, handling characteristics, or structural integrity of the rotorcraft. Developing such an innovative and beyond-the-state-of-the-art concept entails enhancing all of the aforementioned techniques and seamlessly merging them to accurately interpret often complex interactions.

PHASE I: Develop a model/sensor-based concept for real-time and autonomous fatigue damage alleviation that can be incorporated directly into a fly-by-wire flight control system. Demonstrate the feasibility of the approach through simulations.

PHASE II: Fully develop the concept into a prototype system that can be implemented and demonstrated in a rotorcraft simulator.

PHASE III: Transition the technology to applicable rotorcraft platforms.

PRIVATE SECTOR COMMERCIAL POTENTIAL/DUAL-USE APPLICATIONS: This technology is applicable to civilian rotary-wing platforms, as well as fixed-wing aircraft.

REFERENCES:
1. Datta, A., & Chopra, I. (2008). Prediction of the UH-60A main rotor structural loads using computational fluid dynamics/comprehensive analysis coupling. Journal of the American Helicopter Society, 53(4), 351-365.

2. Gunsallus, C. T. (1989). "Rotor System Load Monitoring Using Minimum Fixed System Instrumentation, Proceedings of the National Technical Specialists' Meeting on Rotorcraft Structures, AHA, Alexandria, Virginia.

3. Haas, D. J., Flitter, L., & Milano, J. (1996). Helicopter flight data feature extraction or component load monitoring. Journal of Aircraft, 33(1), 37-45.

4. Ho, J. C., Yeo, H., & Ormiston, R. A. (2008). Investigation of rotor blade structural dynamics and modeling based on measured airloads. Journal of Aircraft, 45(5), 1631-1642.

5. Johnson, W. (1998). "Rotorcraft aerodynamics models for a comprehensive analysis," Proceedings of the 54th Annual Forum of the American Helicopter Society, AHA, Alexandria, Virginia.

6. Potsdam, M., Yeo, H., & Johnson, W. (2006). Rotor airloads prediction using loose aerodynamic/structural coupling. Journal of Aircraft, 43(2), 732-742.

KEYWORDS: Structural Health; Usage Monitoring; Diagnostics; Prognostics; Fly-by-Wire System; Damage Alleviation

** TOPIC AUTHOR (TPOC) **

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