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The Art of Inspecting Aircraft

Aircraft AME’s and technicians spend a great deal of their time simply inspecting aircraft on a regular schedule which does not even include the maintenance and repairs but just coming up with a personal assessment of the aircraft condition based on specific regulatory and industry standards. The various inspection techniques used by the professionals in our industry are foundational to the continued airworthiness of the aircraft that we operate in everything from training, recreation or business to commercial air travel. For the purposes of this article, whenever we describe the process of inspecting aircraft, the person performing the task may be referred to interchangeably as either an AME, Technician, or Inspector. I also may use the terms “we or our” to acknowledge my own background and experience with aircraft inspections. The goal here is to simply bring certain nuances of the inspection process into the forefront of our collective maintenance functions.

Experience and ongoing training are constantly influencing aircraft maintenance professionals in not only what to look for, but also how to actually see what they are looking for. Visual inspection for condition is really one of the most critical stages of maintaining aircraft - known better as preventative maintenance. Technicians are well aware that their findings are the direct result of their performance during the investigative process. Developing good inspection habits effectively represents the difference between looking and seeing. These habits are difficult to teach as the diligence and desire to learn must come from within the individual actually performing the work amidst the many challenges of competing thoughts and biases that they may have. Not all inspectors of aircraft are the same nor will they always produce the same findings. Just like pilots, we are always learning! Therefore, the art of inspection is a key attribute that is often overlooked when determining the quality of the overall maintenance experience. Let’s explore some of the finer points of the inspection process.

Gaining the necessary experience through this progressive discipline also permits a better working knowledge of the aircraft structure and its systems. Maintenance personnel reference check sheets and service information as the accepted norm to guide them through the scope of their tasks. While the check sheets and technical references are essential to meeting specific standards, the experienced eyes of the technician are most valuable for determining where something doesn’t look right according to their familiarity with the aircraft. Things that don’t look right may stand out (beyond the normal wear and tear) as clues to substandard work practices, suspect parts or materials, or even a new understanding of the aircraft operating environment or time in service. The aircraft construction itself may demand specific experience in wood and fabric, steel tube, aluminum, or advanced composites.

Inspecting aircraft requires a certain measure of skillful and ethical consideration in order to determine the most effective results. Looking at aircraft but not expecting to see anything wrong is a dangerous form of expectancy that actually distorts our perception of any issues that may exist right under our nose. So, in essence, it may be beneficial for the inspector to be fully prepared and determined to find clues of non-conformance even in areas that don’t normally present any concerns. It is the attitude we have towards our inspection responsibilities that often determine our outcomes. We may have heard the old adage from “thrifty” owners that says “don’t look too hard, I don’t want you to find any problems that could cost me more money”. As funny as that sounds, in some cases they are serious! But that is not the way we are obliged to conduct ourselves. Dealing with the facts and the findings is the only safe way forward. Find and document the issues, assess the issues for serviceability and airworthiness, then make a plan to restore and release a safe product back into the sky.

The act of performing an Inspection on an aircraft structure or component is the vital process by which the inspector must first seek, identify, evaluate then determine the true condition of the aircraft. The inspection itself then, is the focused assessment of its condition by use of sight, feel, measurement, or any other means deemed appropriate to the type of work undertaken. It is the gathering of the information or data required to make a sound judgement in determining the type of maintenance that will be required. The quality of this information may also be influenced by various human factor and/or psychological elements. Complacency, for example, can be a very unsuspecting enemy. In order to sharpen our inspection skills, we must raise our consciousness and dutifully accept the fact that inspecting aircraft is not simply a passive activity. This is what we train for on a recurring basis and this is what we contribute to the documented work package. Once the inspection phase has been completed, maintenance then encompasses the actions necessary to sustain or restore the integrity and performance of the aircraft to an airworthy condition. Two very distinct yet essential phases of work in the form of a 100 hour or Annual inspection.

The primary means of inspection is visual – with our eyes – to look directly at the subject task with aided or unaided visual contact. Our visual inspection may be further improved through aided enhancements which include the use of magnifiers, borescopes, or specialized equipment. Another important and often underrated means of inspection is tactual – with our hands – to actually handle and feel the material to determine its condition. Sometimes it is more effective to actually touch the work in order to detect problems beyond what you may be limited to by sight alone. This could include sensing some “play” in a fastener attachment or “wear” on a control cable that could have only been discovered through tactile senses. We can also perform Non Destructive Testing (aka NDT) on parts which require a more in-depth inspection to determine the integrity of a material beyond mere detection by normal sight or feel. The use of NDT is sometimes mandated by an AD or Service Bulletin in order to ensure effective results on a specific part or structural area. This may even include a specific method of NDT be used to achieve the desired result in the best possible manner (such as magnetic or dye penetrant). Technicians are also required to use tools like calipers and micrometers to determine dimensional limits sometimes measured in increments of “thousandths of an inch” or as otherwise specified by the manufacturer. All of these supplementary aids are considered the standard tools of the trade but are only effective if used properly and in the right situations

.Performing an Independent Inspection is the accepted means by which we can double-check our work on engine and flight control systems. This is also known as a dual inspection because it requires confirmation from two individuals that the work affecting control systems was performed correctly. The inspection extends to functional checks of these systems to ensure proper direction and sense of operation. These types of inspections are mandated by a regulatory requirement but can always be used as an internal company procedure to simply “cover our behind” after any type of work was completed. This is a great example of internal quality control because the work is being reviewed and documented (as such) immediately after its completion. Quality Assurance is an internal company process used to review the effectiveness of a work process and may ultimately produce continuous improvement strategies in this area and/or other related functions.

Another significant aspect of personal preparation is the tools that we work with on a regular basis. When it comes to visual inspection, it is absolutely necessary to use a good flashlight to properly illuminate the area. A flashlight should be one of the primary tools for AME’s and technicians at all levels of experience. I have seen many types of light sources over the years and am convinced that the quality of inspection can be influenced either by a poor light source or a great one. Nowadays we have the luxury of LED products which are now far superior to some of the dim household models I have seen in the past. Even the basic cleaning of certain areas (such as undercarriage or powerplant) may be necessary prior to inspection in order to produce accurate conclusions from these inspection areas.

Inspecting any aircraft includes the “easy to access” areas as well as the more difficult areas regardless of the aircraft type. Areas which are difficult to access could also impact reliable findings and therefore require an appropriate light source and inspection mirror at minimum. Technicians are often challenged to do whatever it takes to gain suitable access to the inner structure and systems to be inspected. This may also require the use of work creepers, stools and step ladders as needed. Even climbing in and around the fuselage requires a certain level of dexterity and comfort to permit a thorough look. Adequate positioning and comfort still influence one's ability to inspect the area well even if it requires a little more preparation.

Our continuing airworthiness requirements, bulletins, alerts and procedures are essentially a work in progress as manufacturers and regulators alike are dependent upon feedback from the field on potential service difficulties. Our experiences also represent a term known as tribal knowledge where best practices, helpful hints and tools of the trade are shared amongst the maintenance community. The way that we work and seek to adopt these practices becomes integral to our mentoring programs and training curriculum. It’s not enough to simply do the job in this safety-sensitive industry but to do it well with all of these factors taken into consideration.

The ultimate goal of performing inspections is to always do the best job possible with adequate resources and training in order to ensure the airworthiness status after a scheduled check. Properly trained technicians are the backbone of the maintenance industry through their acceptance of this responsibility with integrity and confidence. Sure, performing inspections may not be as interesting as doing repairs or modifications, but it is nevertheless a critical part of the maintenance process.

The following passage has been quoted from the book, The Aviation Mechanic by Norcross and Quinn, copyright 1941. It is obviously dated in some respects but nevertheless carries a timeless message in addressing the role of the maintenance person;

“In no other kind of work, except medicine, does so much responsibility depend upon the individual man. Before a young physician is graduated from medical school he takes a solemn oath swearing he will live up to the great traditions of the medical profession. In aviation we have no formal pledges. But from the youngest mechanic in our shop right on up to the chief pilot of the airline, every man knows that he is being counted on for the best that is in him – the last full measure of devotion – if you want to call it that. That’s what we expect. That’s what we get.

So when we take on a new mechanic we are looking for a man with specific qualities. Perhaps we are searching for integrity, honesty, and dependability even before we look for technical skill. In this new-fashioned business of aviation, we have gone back to old-fashioned qualities. In aviation, honesty and integrity are basic.”

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