Identification, Evaluation, and Causal Factor Determination of Maintenance Errors Common to Major U.S. Certificated Air Carriers

Abstract

A mixed methods study was conducted to identify common errors, causal factors and corrective actions related to maintenance errors that have occurred on aircraft operated by major U.S. air carriers.  Initial review of FAA compliance action letters obtained via FOIA for American Airlines, Southwest Airlines, and United Airlines identified errors and causal elements for categorization and further study.  Study participants were randomly selected from FAA listings of certificated mechanics and asked to complete a survey.  Quantitative data was acquired from participants who completed the survey and qualitative data was acquired by interviewing a selection of those who completed the initial survey.  The study found common errors with the completion of maintenance entries, handling of maintenance documents, content of maintenance instructions, installation of parts, deviations from maintenance procedures, and maintenance steps or tasks that were overlooked or not performed.  Dominant causal factors were identified as failure to follow instructions or procedural requirements, and maintenance instructions that contain inaccurate information or lacked sufficient detail.  Dominant human factors identified in the study were complacency and lack of attention.  Repetitive or simple tasks were identified as a contributor to complacency and the failure to follow instructions.  Demands on mechanics to quickly return aircraft to service also contributed to the performance of maintenance without the use of instructions.  Corrective actions included rectification of the initial errors, counseling of employees, and correction of instructions and documentation.