Identification, evaluation, and causal factor determination of maintenance errors common to major U.S. certificated air carriers

Abstract

The purpose of this mixed methods study was the identification of common errors, causal factors and corrective actions related to maintenance errors affecting aircraft with more than 70 seats and operated by major U.S. air carriers. FAA compliance action letters obtained by FOIA for American Airlines, Southwest Airlines, and United Airlines were examined to identify errors and causal elements for categorization and further study. Delta Air Lines letters were requested but not provided by the FAA. Participants were randomly selected from FAA listings of certificated mechanics and asked to complete a survey. Quantitative data was acquired from 48 participants that met selection criteria and completed the survey. Qualitative data was acquired from interviews conducted with nine of the survey participants. Using the categories developed from the FAA data, 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 and process instructions that contain inaccurate information or lacked sufficient detail. The dominate human factors identified in the study were complacency and lack of attention. Study participants noted that complacency was primarily responsible for failure to follow instructions. Performance of repetitive or simple tasks was a causal factor that drove complacency. Direct or indirect demands on mechanics to quickly return aircraft to service also contributed to the performance of maintenance without the use of instructions. Significant corrective actions taken by air carriers included the imposition of controls to prevent the release of flight plans for aircraft that have overdue inspection items, improvements to allow for greater access to maintenance manuals, and a program for the review of instructions by maintenance personnel prior to publication. Suggested corrective actions include automation of manual processes used to track recurring inspections, improved drafting of instructions with mechanic involvement, improved training of new mechanics to instill good habits and providing maintenance instructions through the use of personal electronic devices.