An Innovative Health Monitoring System for Aircraft Landing Gears

The health monitoring of structures has been receiving increased emphasis especially in the design phase of modern aircraft and any transportation system, where dynamic loads can produce high amplitudes of vibration leading to undesirable effects, or new materials susceptible to hidden damages are used, leading to frequent and costly maintenance operations. The main goal of the project is to study and develop a Health Monitoring & Management System (HMMS) capable to give information about the health status of a landing gear of a military trainer aircraft. The HMMS is a distributed system able to prevent and diagnose possible defects or failure occurrences, to analyze its effects and evolution, and to trigger the maintenance workflow in order to safely maintain of the aircraft at reduced costs, requiring minimum human intervention only when needed. This is done by gathering data from a network of sensors, and using specific algorithms to perform a data signal processing and a health status estimation. Then an appropriate DSS (Decision Support System) has been developed to calculate, on the basis of the actual load history, the remaining life according to the standard procedure adopted and accepted by the certification authorities but taking into account the actual scenarios experienced by the aircraft. The SHM system is based on a multiple sensor approach: • ultrasonic waves, activated and sensed by piezoelectric patches bonded to the most critical structural component; • MEMS accelerometers, measuring in differential system parameters evolution at crucial locations of the landing gear • optical fibers (FBG) bonded to the most stressed locations of the landing gear. This integration allows to reduce non-routine maintenance because of its effect on schedule reliability and airplane downtime. Over the aforementioned sensors the HMM system integrates also the traditional ones adopted in landing gears. All the HMM system featured have been widely investigated using numerical tools and subcomponent testing. Finally fatigue and drop tests have been executed for the final assessment of the HMM system capabilities