Remember the accident on the Boeing 737 in Hawaii where the top of the aircraft came off, sucking a stewardess with it? The cause? Skin cracks that let go at cruising altitude. Wouldn't it have been great if those cracks had been discovered BEFORE that accident? Well, there are some new sensors being developed that will do just that! Pretty cool, huh? They are called energy-autonomous sensors and they can detect dents or cracks in an aircraft's skin and send a radio signal to the maintenance department advising them of the imperfection. The sensors are light – they don’t need any cables or batteries. They draw their energy from the temperature difference between the outside air (about minus 20 to minus 50 degrees Celsius) and the passenger cabin (about 20 degrees Celsius). Because there are no batteries to change, the sensors can be located at inaccessible places on the aircraft. As the technology improves these sensors will be built into the aircraft and provide an additional layer of safety and help to the mechanics tasked with maintaining them. Until then we will have to continue to rely on our aviation maintenance technicians to detect these imperfections and cracks. Until next time keep your wings straight and level Hersch! JetAviator7 I have long been on record that I believe our probable cause findings are primarily a vehicle for affecting positive changes, and not for placing blame. In accident investigation and prevention efforts, I don't believe that we are constrained to a narrow construct of causality. — John K. Lauber, NTSB, in a board report of an April 2, 1992, CFIT accident in Hawaii, published in 1993.