Causes and Trends in Maintenance-Related Accidents in FAA-Certified Single Engine Piston Aircraft

Journal of Aviation Technology and Engineering, Sep 2015

The accident rate for general aviation remains high. While most general aviation accident studies have been pilot-focused, there is little research on the involvement of aircraft maintenance errors. We undertook a study to answer this question. The Microsoft Access database was queried for accidents occurring between 1989 and 2013 involving single engine piston airplanes operating under 14CFR Part 91. Pearson Chi-Square, Fisher’s Exact Test, and Poisson probability were used in statistical analyses. The rate of maintenance-related general aviation accidents was 4.3 per million flight hours for the 1989–1993 period and remained unchanged for the most recent period (2009–2013). Maintenance errors were no more likely to cause a fatal accident than accidents unrelated to a maintenance deficiency. Inadequate/improper maintenance (e.g., undertorquing/non-safetied nuts) represented the largest category causal for, or a factor in, accidents. Maintenance errors involving the powerplant caused, or contributed to, most accidents, but did not carry a disproportionate fraction of fatal accidents. Noncertified airframe and powerplant (A&P) aircraft maintenance technicians (AMTs) performed maintenance on 13 out of 280 aircraft involved in maintenance-related accidents.While there is current concern as to the safety of the aging general aviation fleet, the fraction of fatal accidents for aircraft manufactured prior to 1950 was not higher than those manufactured more recently. We conclude that the general aviation accident rate related to maintenance deficiency, while low, is static. Increased emphasis should be placed on tasks involving torquing and improper rigging as well as maintenance related to installation/assembly/reassembly. Whether a maintenance error decision aid plan, shown to reduce maintenance errors at airline facilities, would benefit general aviation deserves consideration.

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Causes and Trends in Maintenance-Related Accidents in FAA-Certified Single Engine Piston Aircraft

Journal of Aviation Technology and Engineering Causes and Trends in Maintenance-Related Accidents in FAA-Certified Single Engine Piston Aircraft Douglas Boyd 0 Embry-Riddle Aeronautical University 0 University of Texas Graduate School of Biomedical Sciences at Houston , USA The accident rate for general aviation remains high. While most general aviation accident studies have been pilot-focused, there is little research on the involvement of aircraft maintenance errors. We undertook a study to answer this question. The Microsoft Access database was queried for accidents occurring between 1989 and 2013 involving single engine piston airplanes operating under 14CFR Part 91. Pearson Chi-Square, Fisher's Exact Test, and Poisson probability were used in statistical analyses. The rate of maintenance-related general aviation accidents was 4.3 per million flight hours for the 1989-1993 period and remained unchanged for the most recent period (2009-2013). Maintenance errors were no more likely to cause a fatal accident than accidents unrelated to a maintenance deficiency. Inadequate/improper maintenance (e.g., undertorquing/non-safetied nuts) represented the largest category causal for, or a factor in, accidents. Maintenance errors involving the powerplant caused, or contributed to, most accidents, but did not carry a disproportionate fraction of fatal accidents. Noncertified airframe and powerplant (A&P) aircraft maintenance technicians (AMTs) performed maintenance on 13 out of 280 aircraft involved in maintenance-related accidents. While there is current concern as to the safety of the aging general aviation fleet, the fraction of fatal accidents for aircraft manufactured prior to 1950 was not higher than those manufactured more recently. We conclude that the general aviation accident rate related to maintenance deficiency, while low, is static. Increased emphasis should be placed on tasks involving torquing and improper rigging as well as maintenance related to installation/assembly/reassembly. Whether a maintenance error decision aid plan, shown to reduce maintenance errors at airline facilities, would benefit general aviation deserves consideration. general aviation accidents; aircraft maintenance; aging general aviation fleet - About the Authors Douglas Boyd, PhD Professor, University of Texas, is an active commercial pilot in single- and multiengine aircraft and is IFR-certified. His current projects/ interests focus on the causes of general aviation accidents. Correspondence concerning this article should be sent to . Alan Stolzer, PhD Professor, Embry Riddle Aeronautical University, holds a PhD in Quality Systems, an Airline Transport Pilot Certificate, and an A&P mechanic certificate. Dr. Stolzer’s research interests include Safety Management Systems (SMS) and aviation safety programs. We are grateful to Brad Wacker at the FAA for supplying general aviation flight hours for 1989. Introduction General aviation, governed by 14CFR Part 91 regulations, includes all civilian aviation with the exclusion of operations involving paid passenger transport—the latter covered under the comparable 14CFR Part 121 and 135 rules. Although accidents for the airlines (14CFR Part 121) have dramatically declined over recent decades (Aviation Safety Institute, 2012; Li & Baker, 2007) , such a decrease is not as evident for general aviation, although preliminary data (NTSB, 2014b) indicate a decline for the most recent year (2013). Still, general aviation accounts for the overwhelming majority (94%) of civil aviation fatalities in the United States (Li & Baker, 2007), and represents an unresolved safety challenge for aviation. Furthermore, general aviation accidents carry an associated annual cost of $1.6 to $4.6 billion to individuals and institutions affected (e.g., family and nonfamily incurring injury and/or loss of life, insurance companies, accident investigation costs) when taking into account hospital costs, loss of pay with a fatal accident, and loss of the aircraft (Sobieralski, 2013) . In all likelihood, these costs would be even higher if litigation costs were assessed as well. Most studies on general aviation accidents to date (Bazargan & Guzhva, 2011; Bennett & Schwirzke, 1992; Groff & Price, 2006; Li & Baker, 1999; Li, Baker, Grabowski, & Rebok, 2001; Rostykus, Cummings, & Mueller, 1998; Shao, Guindani, & Boyd, 2014) have focused on the pilot either in terms of pilot error, or corresponding risk factors such as pilot flight experience, certification, demographics, and flight conditions. This is not surprising since the airman has been faulted in 55–85% of general aviation accidents (Li et al., 2001; Shkrum, Hurlbut, & Young, 1996) . Therefore, the remaining general aviation accidents likely have pilot-independent causes, and it is hypothesized that maintenance errors represent such a subset. No peer-reviewed studies on the involvement of aircraft maintenance errors in general aviation accidents (...truncated)


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Douglas Boyd, Alan Stolzer. Causes and Trends in Maintenance-Related Accidents in FAA-Certified Single Engine Piston Aircraft, Journal of Aviation Technology and Engineering, 2015, pp. 17, Volume 5, Issue 1,