Early Warning System for Detecting Fatigue Cracks in Aircraft

Today's aircraft must operate reliably and safely at all times. An active sensor/actuator system helps to detect concealed fatigue cracks in aircraft bodies, thus reducing maintenance times considerably.
If a tiny crack in the hull of an aircraft remains undetected for a long time, it can easily spread and put passengers’ lives at risk. Each component is therefore subject to international maintenance regulations: Aircraft bodies must be thoroughly inspected every 15 to 18 months, depending on the type of plane. This often requires the technicians to dismantle an aircraft’s interior lining – an expensive and time-consuming process involving several days of downtime in the hangar.
If a component is defective, it oscillates at a different frequency from one that is intact when stimulated by the actuator– just as a cracked glass sounds different from an undamaged one when you tap it with your fingernail. In this way, the researchers can accurately track down faults and monitor their development – be it fatigue cracks in the hull and wings, or rivets and other joining parts coming loose. This form of observation is referred to as ‘structural health monitoring’ (SHM).
With the help of this system, any damage behind the lining or in difficult-to-reach places can be identified quickly and easily, thus reducing maintenance times and inspection costs. The system will then also be suitable for use in vehicle manufacture or engine and plant construction.