This paper presents an application of resistive ladder sensors for health monitoring of an aircraft structure. Cracks forming can affect significantly the integrity thus the use of methods which enable damage detection as early as possible is an important issue. The article presents novelty in approach to detect fatigue cracks in the early stage with use of Resistive Ladder Sensors. Additionally, measurement results for customized sensor are delivered, which is design and manufactured on site with conductive paint in DW (direct-write) technique. Moreover the article will present on-line diagnostics capability for the real aircraft elements (including shape complicated) as well as results of the damage detection from full scale fatigue test of turbo-prop military trainer.