DOT/FAA/CT-83/77 (DOT-VNTSC-FAA-83-7), FINAL REPORT: ANALYSIS CONCERNING THE INSPECTION THRESHOLD FOR MULTI-SITE DAMAGE (DEC-1993)

DOT/FAA/CT-83/77 (DOT-VNTSC-FAA-83-7), FINAL REPORT: ANALYSIS CONCERNING THE INSPECTION THRESHOLD FOR MULTI-SITE DAMAGE (DEC-1993)., Periodic inspections, at a prescribed interval, for Mult-Site Damage (MSD) in longitudinal fuselage lap-joints start when the aircraft has accumulated a certain number of flights, the inspection threshold. The work reported here was an attempt to obtain justification for the threshold. It is based upon an analysis of fatigue data for lap-joints (riveted as well as riveted plus bonded) of a configuration closely resembling those in several types of aircraft. Depending upon the definition of threshold, the results show that it will be around 30,000 flights. Graphs are supplied upon the basis of which airworthiness authorities can determine a threshold in accordance with their preferred definition, and for different service conditions.