When it comes to airworthiness, there is a distinct connection to flight safety. When a defect is present in the aircraft, it significantly affects airworthiness and can cause the aircraft to fail to meet the required conditions for safe operation. Even relatively minor aircraft system faults can influence flight safety and increase aircraft downtime.
An article in the New York Times by William Langewiesche spoke about the safety implications of a declining level of aircraft systems knowledge among new pilots. The article said, in part, that airlines are meeting the growing demand for pilots by reducing the experience qualifications for employment, and that handling failed or partially failed systems is a secondary concern when it comes to selecting new hires. As a result, a deep understanding of aircraft systems operation is becoming a less common trait among pilots.
Before we get into the impacts of aircraft system failures on flight safety, it's important to understand the different types of maintenance. The image to the left is what we call “reactive maintenance” because we are reacting to the appearance of a fault. Ideally, we would like to prevent faults from ever being noticed in the cockpit. To do so, it is necessary to see the failure coming and take action before it occurs. This requires us to detect signs of deteriorating health and to correlate that to the responsible component. Luckily, some tools and methodologies can be applied to such a task.
Condition-Based Maintenance (CBM) strives to detect components that are in the process of failing. Those signs are, generally speaking, low-level error message patterns and conventional monitoring for adverse trends in temperatures, pressures, vibration characteristics, etc. – that indicate signs of failure are starting to appear. The fact that the aircraft is producing early signs of failure puts this into the category of Condition-Based Monitoring, even if the cockpit is not yet aware.
Predictive Maintenance (PdM), on the other hand, strives to go one step further. It attempts to predict the future failure of a component on a perfectly serviceable aircraft when there are no signs of failure present. PdM detects future failures by monitoring the stream of system parameters on normally operating equipment. It is looking for “leading indicators” that have been established beforehand, through rigorous analytics focused on given aircraft accidents due to system failure. The search for each leading indicator is a sizeable scientific endeavor
We all want to reduce the total time that faults are present on an aircraft for operational efficiency, but there is also an automatic benefit to flight safety. Essentially, faults that are fixed quickly or pre-empted through early detection are not able to distract pilots in the cockpit.
Note that faults that are significant enough to ground an aircraft are not the topic of this article, as grounded aircraft pose no flight safety risk. That said, when a grounding fault first appears during flight, it creates a distraction, so that remains a concern.
There are two broad categories of aircraft accidents due to system failure that do not ground the aircraft: Faults with which the aircraft can still fly, and recurrent faults that elude attempts to repair them.
Aircraft are permitted to fly with certain functions inoperative, if the conditions specified in a document called the Minimum Equipment List (MEL) are satisfied. The MEL is what may permit an aircraft to fly with an inoperative brake. An aircraft flying under MEL is flying with the failure on board along with any associated cockpit distraction. The faster the failure is fixed, the fewer hours the aircraft flies with that cockpit distraction. As such, fast remediation is called for and a first-time fix is an ideal outcome.
With recurrent aircraft system failures, a problem has been evaluated with the possibility of a positive action being taken, perhaps a part replacement, resulting in the aircraft being declared serviceable. Sometimes the “fix” is a reset, whereupon the symptom vanishes, and the aircraft is declared serviceable. However, the bottom line is that the repair attempts have been unsuccessful, and the fault returns on subsequent flights.
Intermittent faults are notorious because they cannot be reproduced on demand, making conventional aviation troubleshooting difficult. A well-experienced expert will be able to recognize the possible causes of an intermittent fault based on data captured during a flight and from behavior observed by the pilots when the fault occurs – in flight, notably.
This is when “global field experience” comes into play. Most faults that happen on a particular aircraft have been seen and solved before – by someone, somewhere. A guided troubleshooting tool like Veryon Guided Troubleshooting can pose insightful questions that lead to a solution that has been effective in the past. The comprehensive fault isolation solution provides interactive and collaborative troubleshooting while capturing new field experiences so you can grow and retain tribal knowledge and improve first-time fix rates resulting in:
Veryon Guided Troubleshooting incorporates validated field experience to provide consistent and accurate aviation troubleshooting procedures. Book your demo today to see how you can significantly improve first-time-fix rates and reduce overall equipment downtime and total repair costs.
Alternatively, some clues may be found in the recent maintenance history of the aircraft, or across the fleet, using a complete solution for automatic identification of chronic aircraft defects, chronic resolution management, and defect analysis to improve aircraft safety and reliability like Veryon Defect Analysis. The advanced web and mobile solution for aircraft recurring defection detection management results in:
Veryon Defect Analysis helps airlines prevent delays and cancellations, save time and money, and improve their bottom line. If you could eliminate or reduce delays or cancelations before they ever happened, would you do it? That’s what Veryon Defect Analysis is allowing companies to do. Want to see it in action? Book your demo today!
The goal with both CBM and PdM is to pre-emptively apply a repair before any effect is noticed in the cockpit. However, when aircraft system failures do occur, software tools like Veryon Guided Troubleshooting and Veryon Defect Analysis serve to minimize their impact in the cockpit by finding the cause in a short period. The less time that failures are affecting the cockpit, the lower the risk to flight safety, maximizing your aircraft uptime.