NDT Certification

Dec. 20, 2006
How it works, how to get it

For the aircraft maintenance, repair, and overhaul (MRO) sector, few diagnostic tools are as valuable and wide-ranging as nondestructive testing (NDT). Whether it is through the use of magnetically induced eddy currents, low viscosity fluorescent penetrants, magnetic particles, X-rays, or ultrasonic waves, the goal of these NDT methods are the same; namely to discover problems in aircraft parts and assemblies before they become serious, without causing damage to the aircraft being inspected.

Not surprisingly, the right to conduct NDT procedures isn’t just given; it has to be earned. Still, for those technicians and engineers who attain this certification, the rewards can be substantial.

“NDT inspectors are the people who ultimately make the ‘Accept/Reject’ decision on which parts are good enough to be attached to an airframe,” explains Steve Gaylord, chairman of the Aerospace Industries Association (AIA) National Aerospace Nondestructive Test Work Group, and manager of supplier quality at Eaton Aerospace.

“They get to make some of the final product-quality decisions that matter most to everyone.” Add the levels of financial compensation possible in the upper echelons, plus the fact that “there’s a dire need for qualified NDT personnel” across the entire aerospace industry, and it’s clear that being NDT-certified can be a wise career choice.


In the aircraft MRO sector, there are a number of NDT standards or recommended practices that can be adhered to. However, the de facto aerospace industry standard is NAS 410. Short for “National Aerospace Standard 410, Certification & Qualification of Nondestructive Test Personnel,” NAS 410 is the civilian derivation of the MIL-STD-410 NDT standard. The AIA is responsible for maintaining NAS-410 and other NDT-related standards.

“NAS 410 is the contractual standard that binds MROs, as maintained by the AIA,” Gaylord says. “However, it is the task of each aerospace company to establish its own NDT programs compliant with NAS 410 and any requirements laid down by equipment manufacturers.

“The AIA doesn’t conduct NDT certification education and testing,” he adds, “that’s the employer’s job.” This said, only a toplevel NAS 410 expert — known as an NAS 410-compliant Level 3 — has the ultimate authority to devise and oversee a given company’s NDT programs.


Every level of NDT certification requires a successful blend of three elements: classroom education, on-the-job experience, and formal testing. However, this is where the similarities end, because the requirements for an NAS 410 Level 1 NDT are far less than a Level 3. Moreover, although a Level 1 can be certified for a narrow range of procedures directly relevant to their technician job descriptions, Level 2s and 3s are typically trained to use a broad range of NDT methods.

Let’s start at the beginning. An NAS 410 trainee is the entry-level NDT position, operating under the direct supervision of a Level 2 or Level 3. During this process, the trainee must take a minimum of 16 hours of classroom training (and pass tests) at his or her place of employment, plus gain 130 hours of practical, hands-on experience, and then be tested for knowledge and technique. In certain cases, an NDT technician can be certified as a “Level 1 Limited,” meaning that they can execute certain procedures themselves. In most cases, a general Level 1 has more authority than a Level 1 Limited, and when approved by a Level 3, their accept/reject assessments must be based solely on test results.

To move up to an NAS 410 Level 2 certification — meaning that the technician gains the general right to make accept/reject decisions — requires another 16 hours of classroom training and testing, plus an additional 270 hours of supervised on-the-job experience. This quantum leap in requirements is essential, given the expanded responsibility open to an NAS 410 Level 2. The reason: Level 2s must have the knowledge and experience to set up NDT equipment and calibrate it to the right specifications; conduct the actual NDT tests and supervise Level 1s who are assisting in the process; evaluate the NDT test results to decide whether a part should be accepted or rejected, and write up reports to record and justify these decisions.

“The Level 2 is the front line inspector,” says Robert Potter, member of the American Society for Nondestructive Testing (ASNT) management council, and vice president of Metal Finishing Company. (Potter is working on ASNT’s efforts to develop an aerospace-specific NDT standard.) “They’re the ones who daily make the big decisions.”

From a career standpoint, Level 2 is as far as many NDT inspectors go. The reason is that Level 3 certified personnel are usually either the people who devise the NDT procedures used at a specific company, or manage those already in place. In fact, “every company must have a Responsible Level 3 — known as an RL3 — on staff and in charge of their NDT programs,” says Gaylord. “A company wishing to set up an NDT program must contract a (NAS 410-compliant) Level 3 to create and administrate the program before turning it over to an RL3 for day-to-day management.”

As with the other levels, those aiming for Level 3 status must meet certain criteria. In this case, they have to pass formal tests, and meet a series of standards including the ability to train Level 1s and 2s; understand the full range of NDT testing methods available, and know how to determine which NDT methods are most appropriate for a given situation.

Besides the three levels, NAS 410 also specifies the qualifications required to become an NDT instructor, and an NDT auditor (someone who audits the NDT procedures of other companies).


Despite the high standards required for all levels of NAS 410 certified personnel, certifications attained at one company are not necessarily transferrable to another. The reason is twofold: First, certification is an employer-by-employer responsibility; there is no centralized NAS 410 testing body that maintains industrywide standards. Second, the NDT tasks required at one MRO may be different from those needed at another.

For those who can foresee switching companies during their career, “it is important to keep copies of your training and experience evidence, as well as past certifications,” says Gaylord. “A person should never rely on a company.”

Such limits aside, gaining NDT certification is a sure way to increase your value as an asset to your employer, and to yourself as a well-paid employee. Besides, being an NDT inspector lets you have a real say in how your clients’ aircraft are maintained. It makes the job more meaningful, on a day-to-day basis.

For more information on NDT certification,
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