Nondestructive testing (NDT) is widely used in aviation. It is a way to determine the airworthiness of an aircraft or component without having to destroy it in the process. Advisory Circular 65-31A, Training, Qualification and Certification of Nondestructive Inspection (NDI) Personnel states nondestructive testing is defined as "inspections, tests, or evaluations which may be applied to a structure or component to determine its integrity, composition, electrical or thermal properties, or dimensions without causing a change in any of these characteristics." When considering ways to advance in an aircraft maintenance career, one option that many A&Ps choose is to specialize in an NDT discipline. But what type of training is required? We will take a look at some of the issues regarding NDT training and certification.Implementing an NDT program
For someone wishing to develop an NDT certification program, what should they do? Well before setting up a training program, the best thing to do is to consult one of the many standards that are out there. (AC) 65-31A is a good guide for developing an NDT program. It lists numerous standards that are available regarding NDT programs including:
- AIA-NAS-410, Aerospace Industries Association, National Aerospace Standard, NAS Certification & Qualification of Nondestructive Test Personnel.
- ATA Specification 105, Air Transport Association, Guidelines for Training and Qualifying Personnel in Nondestructive Testing Methods.
- Canadian National Regulations contained in CAN/CGSB-48.9712-2000, Qualification and Certification of Nondestructive Testing Personnel.
- International Standards organization (ISO) document: ISO 9712, Nondestructive Testing ' Qualification and Certification of Personnel.
- MIL-STD-410E, Military Standard, Nondestructive Testing Personnel Qualification and Certification (acceptable, although now rescinded).
In addition, it says that individuals who meet the criteria established by the following certification programs may be deemed qualified after FAA review of the specific written practice establishing certification criteria:
- American Society for Nondestructive Testing Inc. (ASNT), Recommended Practice SNT-TC-1A, Personnel Qualification and Certification in Nondestructive Testing.
- Certain international NDI standards accepted by other approved regulatory agencies and national qualification programs have been, and may be considered to be, acceptable standards. In particular, European standard prEN 4179, Qualification and Approval of Personnel for Nondestructive Testing, is acceptable.
Also, other standards or alternative methods of qualification and certification may be satisfactory if found acceptable by the Administrator.
Is it necessary to be certified to a standard?
One of the biggest controversies that comes to light when talking about NDT is that of certification. Many A&Ps will say, "I am an A&P. I don't need any additional certification to use NDT equipment." Consider FAR 65.81(a). It states that a certificated mechanic "'may not supervise the maintenance, preventive maintenance, or alteration of, or approve and return to service, any aircraft or appliance, or part thereof, for which he is rated unless he has satisfactorily performed the work concerned at an earlier date. If he has not performed that work at an earlier date, he may show his ability to do it by performing it to the satisfaction of the Administrator or under the direct supervision of a certificated and appropriately rated mechanic, or a certificated repairman, who has had previous experience in the specific operation concerned." So clearly, an A&P may not perform a nondestructive test of a part unless he or she has performed that test before. But that is where it gets tricky. Some would say that performing it once under the supervision of another mechanic experienced in that particular NDT method would qualify somebody to perform that test. Don't assume this. Both the performance of nondestructive inspections and the interpretation of the results require skill, and must only be performed by properly trained personnel. Mechanics need to consider the training necessary in order to properly perform these tests.
What the standards do
The standards out there set the groundwork for the training necessary to become proficient at various NDT disciplines. Referring to them is a way to ensure you are a qualified inspector. It is a way for the industry to ensure they are all on a level playing field in terms of NDT certification. If you attend a training class, you can bet that you will be trained and certified in accordance with one of these standards.
There are five basic nondestructive testing methods. They are:
- Magnetic particle
- Liquid penetrant
- Eddy current
Training and testing must be accomplished in each specialty. For example, someone may be a Level III in liquid penetrant inspection, but only a Level I in eddy current. You need to pursue certification in every discipline that you want to use. The good news is that the total hour requirements for each level is usually lessened slightly when more than one certification is obtained.
Levels of certification
Whatever the organization that you follow to get NDT certified, the certification will usually fall into three levels ' Level I, Level II, and Level III. Here is how these levels are generally broken down.
Level I Special: This is the lowest level of qualification, and is sometimes used where task specific qualification is necessary. Personnel may be qualified to this level in order to perform a specific task on a component inspection. Instruction and OJT are normally limited to the specific requirements to perform the task.
Level I: This is the common introductory level for a specific inspection type. In order to qualify for Level I, individuals should have the skills and knowledge to perform specific tests, specific calibrations, specific interpretations and evaluations for acceptance or rejection, and document the results in accordance with specific procedures. The individual should be knowledgeable of necessary part preparation before and after inspection. He should be able to follow procedure pertinent to the techniques for which he or she is qualified, and receive guidance or supervision from a Level II or III inspector.
Level II: This level is for more advanced inspectors. In addition to meeting all the requirements for a Level I, the individual should have the skills and knowledge to set up and standardize equipment, conduct tests, and interpret, evaluate, and document results in accordance with applicable procedures. The inspector should be thoroughly familiar with the scope and limitations of the methods for which he or she is qualified and be able to provide on the job training (OJT) for trainees and other inspectors.
Level III: These are the top dogs in the NDT arena. Level III inspectors must meet all the requirements of a Level II. In addition, they should have the skills and knowledge to interpret codes, standards, and other regulatory documents that will affect the NDT methods used by the organization. They should be able to select inspection method and techniques necessary for specific inspections, select and/or design equipment and reference standards, verify the adequacy of procedures, and have a good general knowledge of all NDT methods used by their organization. They should also be capable of conducting or directing the training and testing of personnel for the methods that they are qualified.
If your company does not offer NDT training, don't worry. There are training opportunities available to get you on the road to certification. Some training companies specialize in NDT training. Also, check with the NDT equipment manufacturers. Many of them offer training and certification for the specialties that they offer.
Whether you get the training at your company or through an outside training provider, obtaining an NDT certification can help you on the way to maximizing your career choices.
Advisory Circular 65-31A Training, Qualification, and Certification of Nondestructive Inspection (NDI) Personnel
Aerospace Industries Association
Air Transport Association
American Society for Nondestructive Testing (ASNT)