The monitoring of safety-relevant load-bearing structures of glass facades, steel pipes, and fiber composite components in vehicles and aircrafts, wind turbines requires long-term stable sensors with high error and spatial resolution. With the help of integrable piezoelectric ultrasonic transducers, ultrasonic pulses in the frequency range 20 - 200 kHz are coupled into the component. A comparison with the original reference image results in deviations of the ultrasonic pulses at the beginning of cracking. Thus, cracks of a few mm in length can be detected with a spatial resolution of about 2 cm.