Jeff Demo

Development of a wireless miniaturized smart sensor network for aircraft corrosion monitoring

Corrosion of aircraft and rotorcraft costs the US military billions of dollars annually, and is by far the largest single maintenance cost driver for Navy and Marine Corps airframes. The various forms of localized corrosion, such as pitting corrosion, crevice corrosion, exfoliation, and environment assisted cracking, are particularly destructive and frequently occur without any outward signs of damage. To maintain acceptable risk levels, costly schedule based inspection and maintenance practices are used. In order to move away from schedule based maintenance and enable condition based maintenance techniques, a miniature corrosion monitoring smart sensor network to support diagnostics and prognostics for aircraft health management is being developed. The development of an ultra-low power, wireless, embedded corrosion monitoring system based on the IEEE 1451.X open architecture for smart transducers will be discussed in this paper. This system, funded through a NAVAIR Phase II SBIR, is capable of monitoring, recording, and analyzing data from environmental and corrosivity sensors for the purpose of aircraft health management. This paper will present the use of a standard network architecture consisting of transducer interface modules (TIMs) and network capable application processors (NCAPs), allowing for ease of system integration and plug-and-play simplicity. The hardware and software designs, relying on ultra-low power components and embedded energy conservation algorithms, will be presented. This low-power approach to aircraft corrosion and health monitoring is ideal for integration with energy harvesting techniques, giving rise to a self-contained, self-sustaining sensor network. Finally, corrosion modeling and embedded algorithm development based on data fusion from both commercial off the shelf (COTS) and novel, developmental sensors will be discussed and shown to be powerful diagnostic and prognostic tools. 1 2

Diagnostics and prognostics for aircraft structures using a wireless corrosion monitoring network

Corrosion of aircraft and rotorcraft is one of the primary maintenance cost drivers for the US Military, costing billions of dollars annually, and is by far the largest single maintenance cost for Navy and Marine Corps airframes. Various forms of localized corrosion, such as pitting corrosion, crevice corrosion, exfoliation, and environment assisted cracking, are particularly destructive and can lead to significant structural integrity problems for aircraft. Widespread current practice employs costly schedule based inspection and maintenance to retain acceptable risk levels. To enable condition based maintenance techniques, Luna is developing a diagnostic and prognostic system based on an intelligent wireless corrosion monitoring network.

Wireless corrosion monitoring for evaluation of aircraft structural health

The military spends billions of dollars annually on inspection, identification, and repair of damage resulting from aircraft corrosion. The currently available methods for identifying aircraft corrosion damage involve expensive, labor intensive scheduled inspections, resulting in longer periods in depot, and reduction in aircraft availability. In order to increase aircraft safety, availability, and operational efficiency, an on-platform monitoring system capable of fusing data streams from an array of environmental and corrosivity sensors is needed to provide inspection-free indicators of the existence of corrosion as well as the level of corrosive severity in difficult to access aircraft locations. This paper will discuss the design, test, and validation of such a system utilizing a wireless, ultra-low power network of sensors.1 2

Deployment of a wireless corrosion monitoring system for aircraft applications

With its extremely negative effects on critical military assets, corrosion continues to be one of the top maintenance cost drivers for the Department of Defense. As of 2010, an estimated

Identification of material damage precursors using nonlinear ultrasonics

22.9B was required to cover the costs associated with corrosion in the DoD annually. Proper management of corrosion on high value military assets such as aircraft can significantly reduce costs associated with maintenance, component removal, and aircraft availability. This paper will discuss the design, validation, and deployment of a wireless, flight qualified corrosion monitoring system as well as analysis of data collected during field trials.

Aircraft contaminant and leak detection sensor system for condition based maintenance

The primary goal of this research effort is to develop nondestructive evaluation techniques capable of detecting material damage precursors mainly for turbine engine materials under low and high-cycle fatigue testing. The experimental results presented in this paper show a significant increase of the relative acoustic nonlinearity, βr, in aluminum and Ni-based superalloy fatigued specimens. While in agreement with the prior research, the main advantage of the current technique over the previous methods is that the ultrasonic beam may be focused to inspect the presence of damage precursors at localized stress concentrator site. For example, when the ultrasonic beam travelled through the root of the round-notched specimens, the acoustic nonlinearity exhibited an increase of approximately 450% as compared to the pristine specimens. This procedure will be further developed to detect damage precursors in propulsion components undergoing thermo-mechanically fatigue to quantify their remaining useful life.

Aircraft corrosion monitoring and data visualization techniques for condition based maintenance

Environmental and chemical contamination has been a serious concern among military and commercial aircraft maintainers. Ingress of contaminants into the structure, occluded areas, and crevices can breakdown protective coatings, initiate localized corrosion, and eventually compromises the functionality or structural integrity of the system, component, or airframe. Leaking or weeping fluid lines or storage tanks within an aircraft can cause standard fluids such as aircraft fuels, hydraulic fluids, or component lubricants to come into contact with sensitive systems or structures. These liquids may cause issues ranging from degradation of polymers and coatings, leaching of corrosion inhibitors from coatings, supporting corrosion, or damaging sensitive electrical and mechanical equipment due to their presence or composition. This paper will discuss an approach for monitoring and evaluating contaminants and leaks that occur within aircraft, in order to address the issue of corrosion related maintenance. A monitoring system is being developed to detect contaminants that may degrade aircraft systems. The contaminant detection system can be mounted within the airframe at low positions, collection points, near critical systems, or sources of concern to detect both the presence and type of contaminants. The monitoring system measures and records environmental parameters such as relative humidity, temperature, surface contaminants, and corrosion rate. The contaminant detection system also measures concentrations of target gases such as SO2, NO2, and hydrocarbons (JP-8 fuel) indicative of the presence of leaks or corrosion inducing conditions within the airframe. The monitoring system has the capability of wirelessly transmitting data to a point maintenance corrosion tool (ICARR-3D) that maps findings and conditions onto three dimensional models of the aircraft. The ICARR-3D maintenance tool was created by Mercer Engineering Research Center (MERC). Sensor node data for a given location within the airframe is sent to the ICARR-3D system along with contaminant severity classification for aircraft maintainers to use in determining the need for inspection or maintenance actions. The ability to identify contaminant exposure within airframes and inform maintenance personnel of leaks, corrosive environments, and chemical contaminants in difficult to access areas will enable condition based maintenance to optimize costs, maintenance man hours, and aircraft availability.

Evaluation of Environmental Exposure and Corrosive Conditions within Rotorcraft Airframes

To provide in situ measurements of environmental severity, the LS2A corrosion monitoring sensor suite has been developed and deployed. This system, a wired or wireless sensor node, measures, records, and analyzes environmental and corrosivity parameters. To support maintenance exposure tracking, autonomous data analysis techniques are being developed to track and visualize environmental severity within airframes for clear, intuitive, and informative presentation of long-term environmental exposure.