Compilation of damage findings from multiple recent teardown analysis programs

Abstract

Fleet managers depend upon various tools to assure the safe operation of their aircraft. Performing a structural teardown analysis program of one or more aircraft with known service history provides precise damage data resulting from a given usage. These data can then be used to validate NDI methods, update damage models and reduce uncertainty in the damage condition assessment of the remaining fleet. In the past six years the USAF Academy Center for Aircraft Structural Life Extension (CAStLE) has been involved, at various levels, in multiple teardown analysis programs. CAStLE's level of involvement has ranged from consultant through failure analysis support to planning and executing all elements of an entire program. In each program large regions of selected aircraft were disassembled by precision means, cleaned of all coatings and inspected by a variety of NDI techniques. These NDI indications were then evaluated by failure analysis methods to determine the root cause of failure-the type of damage which resulted in the NDI indication. Failure analysis findings which were a result of aircraft operations were further analyzed to obtain detailed damage characteristics. This work presents a summary of findings from teardown programs conducted on eight aircraft ranging from small military trainers to large transports. Comparisons are presented for damage types and categories of aircraft. Damage type and scale is also presented categorized by the type of damaged component (skin, stiffener, fitting, etc.). Data are also provided with regard to measurable features within regions of damage initiation. © Us government 2009.