Survey of Structural Repairs and Alterations in Transport Category Airplanes

The work presented here details a survey of structural repairs, alterations, and modifications (RAM) on transport airplanes that was conducted over the past year and a half as part of a two-year project. The goal of this effort is to provide data to better understand the risks that RAMs may pose for developing widespread fatigue damage (WFD). Surveys were conducted on retired airplanes at aircraft salvage locations and on in-service airplanes at the operator' heavy maintenance locations and will be compared to a similar survey conducted by the Airworthiness Assurance Working Group in the 1990s. Additionally, specimens from retired airplanes were acquired and in-depth teardown inspections were performed to look for the presence of damage indicative of WFD. A database was developed to analyze the data for WFD risk assessments. Once completely populated, recorded data will be examined for trends to quantify the risks that RAMs may pose for developing WFD.