The Federal Aviation Administration (FAA) Aviation Research Grants Program has awarded the Helicopter Association International (HAI) a cooperative agreement to support research titled “Validation of FAA AC-29-MG for Usage Credits”. “HAI is pleased to be working with the FAA on this important project” says Matthew Zuccaro, HAI President. “The ability of the Health and Usage Systems (HUMS) to detect mechanical degradation significantly reduces unscheduled maintenance of the power train, enhancing aircraft availability and avoiding mechanical failures in flight. In addition, this technology measures the intensity of operational usage in a way that promises to extend the safe lives of components that are subject to less demanding operational use.”

Unlike fixed-wing aircraft, helicopters perform a variety of missions from heavy lift to transportation, and the useful life of dynamic components varies from mission to mission. But until the advent of HUMS little consideration has been given to the life of a part based on actual usage. When fully implemented the collective impact of these and other features of the HUMS will be an increase in safety and operational efficiency throughout the rotorcraft industry.”

The safety contribution of HUMS equipment was verified by the International Helicopter Safety Team (IHST), formed in 2005 to reduce the helicopter accident rate by 80 percent in ten years. The group chartered the Joint Helicopter Safety Analysis Team (JHSAT) to perform a data driven analysis of all accidents on an annual basis by statistically analyzing the root causes for every accident in the data set. This methodology was successfully used by the Commercial Aviation Safety Team (CAST) for the air carrier fleet. The JHSAT reported “The development, installation and use of HUMS on aircraft to monitor the status of the aircraft systems and their level of use, or equivalent Engine Monitor Systems (EMS) is a predominant system failure intervention. The JHSAT has identified 24 (47 percent) of the part/system failure accidents that may have potential for mitigation by monitoring systems.” The full report can be found at www.ihst.org. In short, HUMS and Conditioned Based Maintenance (CBM) have the potential to increase operational efficiency, improve safety, and aircraft availability.

HUMS equipment is starting to be deployed in the civilian helicopter industry. These systems typically consist of a variety of sensors and data acquisition systems.  The three basic aspects of HUMS are installation, credit validation, and Instructions for Continued Airworthiness (ICA). Although installed on a number of aircraft, to date there has not been a successful application for a “maintenance credit.”

HAI has put together a team of industry experts and is joining the effort to support the FAA and the industry as a whole to document the steps needed to validate the processes needed to provide flight time extensions for components subject to the least severe operational loads. If you have had experience operating helicopters with HUMS functionality, especially if you now operate HUMS equipped aircraft, we would like to hear from you. Please contact ed.dicampli@rotor.com with a summary of your experience.