History of Human Faith in Material
Systems and technologies that verify the durability of materials in use were not always as in-depth and thorough as those used nowadays in services such as aircraft NDT. More primitive inspections may have been simple examinations done by the naked eye, and an early type of destructive testing that likely involved using the materials that did not break.
Over the span of centuries, mankind has placed great trust in the inventions we created and the hopefully reliable materials used to bring them to fruition. Including the wood used to secure populations, defend a warrior in battle (shields), and even take sailors across unpredictable oceans in early days. Under the scrutiny of today’s standards, this would pose extreme risks because we now understand that the durability of material diminishes through time and natural weathering, and need to be inspected regularly.
This understanding introduced the need for systems and technology to inspect the various elements presently used for cars to drive us at high speeds cross-country, large ships prepared for angry seas, and aircraft flying high overhead, sometimes with almost 100 passengers. Though our faith in materials employed seems tainted by inspections, they actually instill needed confidence in our constructs and ability to safely complete long journies. How comfortable would you be in an airplane that has never undergone an aircraft inspection?
Why Aircraft NDT?
Conceptualize an aircraft that does regular trips from New York to London, which is 3008.39 nautical miles according to Prokerala, and consider after how many trips without aircraft NDT would this be a flight that you would not board. Many structural material defects that could compromise the safety of an airplane are not able to be seen by a quick look over or even a “thorough” inspection by the naked eye, and you can’t just break the material down every time inspections roll around because replacement costs would be through the roof.
For this reason, service providers such as AMI Aero Marine Interior, Inc. offer aircraft NDT, making use of specialized equipment to inspect the durability of materials without destroying the actual pieces in commission. The various pieces of equipment used for Non-Destructive Testing can also be used without disassembling the aircraft, which blends perfectly into such a time-sensitive industry.
Society has come a long way from primitive forms of safety inspections, yet back then we did not have to worry about airplane components deteriorating. Presently, we have a variety of advanced equipment with aircraft NDT capabilities. Radiography, eddy current, phased array ultrasonics, infrared thermography, magnetic particle, ultrasonics, and liquid penetrant; all pieces of equipment used by AMI Aero Marine Interior, Inc. for Non-Destructive Testing and described on the website page linked as the following:
- Radiography – This type of inspection uses high-frequency penetrating radiation in the form of X-rays to locate discontinuities in a material, verify the integrity of internal components, and determine the quality of welds. There are many advantages to radiography including inspection of a wide variety of material types with varying density, ability to inspect assembled components, minimum surface preparation required, sensitivity to changes in thickness corrosion, voids, cracks, and material density changes, the ability to detect both surface and subsurface defects and the ability to provide a permanent record of the inspection.
- Eddy Current – The overall inspection process consists of applying the Eddy Current Test (ET) Method to detect surface or subsurface cracks in the item inspected. The material tested includes ferromagnetic and non-ferromagnetic materials such as steel, aluminum, copper, and titanium, to name a few. It detects surface and subsurface flaws using state-of-the-art equipment and allows the inspection of aircraft components and structures for cracks, corrosion, and conductivity caused by fatigue, stress, and extreme heat. Our techniques include surface and subsurface inspections, rotating bolt hole inspections, and conductivity measurements.
- Phased Array Ultrasonics – Phased array ultrasonics uses the general principles of ultrasonic testing and computer software to apply several UT beams to an article and manipulating them to an LCD screen. Inspecting parts with variable-angle beams maximize detection regardless of the defect orientation while optimizing the signal-to-noise ratio.
- Infared Thermography – This method is an advanced visual inspection that utilizes infrared technology (cameras) to view the heat profile of an object. The software used in the cameras is able to read temperatures and displays this parameter in a color format. IRT is used to find flaws such as delamination, voids, impact damage, cracks and water ingress in Thin Material, Honeycomb sections and composite material without removal of paint. It is also used in many non-aircraft applications such as building insulation inspection, electrical wiring, rotating machines and various heat sensitive equipment. Permanent records of inspections are stored electronically and can be review at any time to read temperature measurements.
- Magentic Particle – Magnetic particle examination (MPI) is usable only on materials having ferromagnetic properties, principally low alloy steels, and heat-treatable stainless steels. It is a sensitive non-destructive method for detecting surface and near-surface cracks and discontinuities. MPI is used in two general types and forms: Visible/fluorescent and dry/wet particle. Fluorescent wet particles offer sensitivities up to 1000 times that of the visible dry methods. However, they both have their use in industry as one method looks for gross discontinuities while the other seeks out minute defects.
- Ultrasonics – Ultrasonic inspection (UT) utilizes sound waves at frequencies between 2.5 to 20 MHz. UT is used mainly for thickness testing and flaw detection in solid materials that can support sound waves – all metals, plastics, glass, and carbon fiber. finding internal and external flaws and can inspect many different parts/sections of the aircraft structure without disassembly.
- Liquid Penetrant – Liquid penetrant (LPI) testing services are reliable for detecting surface-breaking flaws in just about any solid material with a non-porous surface. A dye is placed on the inspection surface and allowed to seep into crevices. The surface dye is then removed and creviced dye is drawn to the surface in a development process to identify discontinuities in the material. The two main types of LPI used are visible and fluorescent dyes, with the fluorescent version of the inspection having an increased sensitivity of as much as 1000 times that of the visible inspection. An advantage of this inspection method is that it is very portable and can be performed at remote locations. Permanent recording of results is possible with the aid of photography.
These trusted instruments are not only used for aircraft NDT but also for building structures where hundreds, even thousands, of people either work or live in. The wide range of use comes from reliable results and meticulous inspection capabilities that allow the public peace of mind in their condos 30 stories above the ground or on a flight soaring 30,000 feet in the air.
Confidence in Aircraft NDT
By understanding the exhaustive inspections done to an aircraft before flight, the public is more at ease flying than ever. It is not like the days when long-distance flights were dangerous and unchartered territory in an aircraft constructed by materials no longer used today. No, current airplanes are expertly and elegantly constructed from the beginning of fruition and inspected periodically for material deterioration. Allowing airliners the confidence to taxi passengers out onto the runway and send them off to spend long hours suspended in flight traversing the seemingly endless airways above mountain and sea.