Friday, October 1, 2004
Certification and Training of NDT Personnel
Certification and Training of NDT Personnel
The training, certification, and documentation of aviation maintenance personnel has been a longstanding concern of the industry. Airframe and Powerplant Mechanics, avionics technicians, and certificated repairman all have strict guidelines that must be adhered to regarding training, documentation, and experience. This is no less true for the nondestructive testing (NDT) specialist.
Nondestructive testing implies a method that will detect defective parts and assemblies while avoiding damage to serviceable items during the course of the inspection process.
Radiography, ultrasonic inspection, dye penetrant, eddy current examination, and magnetic particle testing are all commonly used disciplines in aviation and other industries. Other techniques, such as X-ray, are also used.
NDT has grown exponentially during the past 30 years in both application and innovation and has done a great deal to improve safety. Some experts say NDT has improved safety more than any other existing technology.
In the aviation industry, NDT specialists come under the regulation of the FAA, as do other aviation maintenance professionals. Contract NDT services must be performed by a certificated FAA repair station. Technicians performing NDT on aircraft, or flight-related hardware, must possess a repairman's certificate or an Airframe or Powerplant certificate.
When contracting for NDT field services, the organization must hold a repair station certificate. There are NDT organizations that specialize in unrelated industries such as petrochemical. They will cheerfully send a pipeline inspector to look at your aircraft, unaware they are not qualified to do the job. To them, NDT is NDT. If this should happen, the customer will pay for services rendered and receive a certification that is null and void in return.
At this time, the FAA mandates that certification and qualification of NDT personnel be performed to the manufacturer's procedure.
While most aircraft companies use specifications such as NAS 410 and SNT-TC-1A, special manufacturer requirements and ratings may be necessary before NDT can be performed. Often, the NDT specialist must attend specific manufacturer classes in order to be certified to test that product.
There is a possibility that at some point the FAA may set minimum requirements for the certification of NDT personnel. To date, this has not happened.
The National Aerospace Standard (NAS 410) is the document that establishes the minimum requirements for the qualification and certification of personnel involved in nondestructive testing. NAS 410 is not a suggested guideline where implemented; it is binding and contractual. It covers the training, experience, and examination of personnel performing NDT in the aerospace and aviation service industries.
NAS 410 specifies seven basic levels of qualification. The employer, for specific applications, may subdivide these further. Where subdivisions are implemented, the requirements and responsibilities will be detailed in the employer's written practice.
Trainee: A trainee is an individual who is participating in a training program for an NDT method and is not certified to perform inspections.
Level I: This is an apprenticeship rating. The Level I individual cannot act independently of Level II or Level III supervision over the course of their daily duties. They cannot accept or reject parts and assemblies or write reports.
Level I Limited: When authorized by the employer's written practice, personnel certified to Level I Limited may perform a specific NDT test or evaluation of a specific part, feature, or assembly. The technician cannot perform tests outside of his or her limited rating.
Level II: The level II individual must possess the skills and knowledge to set up equipment, interpret specifications, conduct tests, evaluate for acceptance or rejection, and file reports. Other duties include, but are not limited to, supervision of Level I personnel, knowledge of other NDT methods, the ability to develop test procedures with Level III approval, and possess basic knowledge of manufacturing and inspection technology. The Level II is the backbone of the NDT industry. They possess all the rights and responsibilities commensurate with performing tests and signing reports.
Level III: The NDT Level III shoulders a variety of responsibilities. They are management personnel and must be capable of assuming technical responsibility for the NDT facility and staff.
The Level III individual must direct training, possess knowledge of other NDT technologies, approve procedures and related work instructions, and be capable of selecting an appropriate inspection method for a given task.
The NDT Level III must possess the comprehension and acumen to interpret codes, standards, and related contractual documents. When required, the Level III must also be capable of auditing outside agencies for technical adequacy.
Instructor: The NDT instructor must have the skills and knowledge to organize and present classroom exercises or on-the-job-training in accordance with approved outlines. Instructors are designated by the employer's Level III or by the outside agency that is responsible for training.
Auditor: The NDT personnel performing external supplier audits must have the education, training, skills, and knowledge to comprehend the processes and procedures utilized in the application of the NDT process. The individual must be familiar with all relevant codes and standards that control the applicable method.
The SNT-TC-1A is a document from the American Society for Nondestructive Testing. Unlike NAS 410, the SNT-TC-1A is a recommended practice that establishes the general framework for the certification and qualification of NDT personnel.
This document provides recommend educational, experience, and training requirements for different test methods. It is intended to be applied with "flexibility and reason."
Because it blankets the NDT industry as a whole, revisions can be made to the specification that are industry specific. This document is not a mandate or contractual agreement, it's a guideline. The SNT-TC-1A is a powerful document that has become a basis or standard for other NDT specifications.
For any given level of certification, the NDT specialist must pass a three-phase testing process that consists of written general and specific tests as well as a practical examination.
The general test covers knowledge of the NDT method and rating applied for, and the specific exam covers required knowledge that is industry specific.
The practical examination is geared to the demonstration of skills and proficiency for the method and rating sought. Finally, the NDT specialist must pass an eye examination for visual acuity and color perception.
This article is intended as a very general overview of the levels of qualification and certification for NDT aviation maintenance personnel.
Due to the complexity of the process, the subject cannot be covered in its entirety; however, the importance of NDT personnel and services they provide to the aviation industry cannot be overstated. -- By Joseph Stump