Advances in Bonded Repair of CFRP Aircraft Structures by Surface Inspection

Due to the increasing amount of CFRP materials in aircraft structures it is necessary to have a reliable repair process. Bonded repair has several advantages in comparison to bolted repair regarding aerodynamic effects or stress concentration in the structure. In case of a damage of CFRP structure contaminants like hydraulic oil or de-icing fluids often appear on adherent surfaces. Due to the fact that these contaminants have a huge influence on the bond strength it is necessary to have a reliable measuring device to monitor the adherent surface before bonding. There are no implemented measuring techniques to monitor the adhesive surface in field of bonded repair available up to now. The two measuring techniques X-ray fluorescence analyses as well as the FTIR-spectroscopy have been tested regarding the detection of contamination on CFRP adherent surfaces in field of bonded repair.