Special probes were developed to test rotor blades for fatigue cracks. These probes utilize ultrasonic surface waves which are highly sensitive to fatigue cracks. The dimensions of the probes were kept small to make possible the testing of blades without the necessity of dismounting. The probes are built up from conventional commercial probes by attaching some small auxiliary equipment to them, which is very easy to manufacture. Searching blades with these probes is more reliable and less time‐consuming than with previously available methods.