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Mechanical failure is the second leading cause of aircraft incidents and accidents (human error is the top). The FAA, after analyzing over 20 years of Part 91 and Part 135 operations, found that 26 percent of all incidents and accidents involved a me- chanical malfunction of an aircraft system. Granted, mechanical failures in aircraft are rare. However, nearly invariably, the aircraft presents signs that things are not normal well before a catastrophic failure takes place. Being attuned to those signs, especially when flying the same airplane regularly, can help uncover problems well before they develop into a catastrophic failures.
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Preflight Deserves More Respect
So why do pilots routinely miss signs of impending me- chanical failure? I find three core reasons:
First, many of us were never taught how to conduct a thorough aircraft preflight. While we all learned how to check fuel and oil levels and how to sump the fuel and check for contamination, most of us never learned what to look for in other areas of the aircraft. For example, how do we identify and spot areas subject to overstress, misassembled hardware or corrosion? What are general trouble areas for the specific aircraft model we are flying? The manufactur- ers’ preflight checklists use generic terms such as “CHECK” and generally do not help with the detailed nuances of a proper visual inspection.
Second, expectation bias presents a major challenge to conducting a thorough aircraft preflight inspection.
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Admittedly, most of the time the plane is in an airworthy state. As a result, we expect the aircraft would be airworthy for today’s flight as well. Flying the same aircraft consistently exacerbates this bias, especially if we own the airplane. It can lead us to skip areas or glance over areas during pre- flight and miss critical items.
Third, many flight instructors are somewhat derelict in teaching the importance of preflight. The “standard practice” is for the instructor to demonstrate a preflight in- spection and maybe observe the student conduct one. From that point on, the instructor will generally say something like, “Go ahead and preflight the airplane on your own.” The instructor arrives after the preflight is complete and off they go flying. In a way, the instructor is sending the message “Flying is important, so I will observe you when we fly together, but preflight is easy and simple, so I don’t need to observe you doing that.”
Fundamentals of a Thorough Preflight
While there is no need for pilots to have the same level of knowledge as an aviation inspector or an A&P IA, hav- ing some mechanical knowledge is very beneficial. It does not take a lot of effort to learn how to identify defects and abnormalities in a preflight. Investing time in acquiring this knowledge and then unfailingly putting that knowledge to use before every flight contributes immensely to flight