Saturday, November 1, 2008
Who Can Perform NDT Inspections?
Non-destructive testing is a maintenance function. But the rules can be confusing. David Schober takes a stab at defining the rules, setting the limits and areas of caution for maintainers.
When dealing with aircraft, the world of certification for nondestructive testing (NDT) can be very confusing.
The first place to look for clarification is the FARs. If we perform a search within the FARs, we find that nondestructive testing only shows up in FARs 25, 145, 147, and 152. FAR 25 deals with the certification of aircraft. FAR 145 is the repair station rules and we will review those requirements later. Part 147 is the rules for aviation maintenance schools, and the curriculum requirements for those schools. Basically anyone that graduated from an A&P school should have been exposed to dye penetrant and magnetic particle inspection techniques. Part 152 deals with airports and is not applicable to this discussion.
Nondestructive testing is a maintenance function. FAR 43 is the primary set of regulations dealing with maintenance, and return to service following maintenance. §43.7 lists persons authorized to perform maintenance and return to service, and they are in short, an A&P, a repair station, an air carrier, and for certain items the manufacturer, and a pilot. Based on the information above, there is nothing listed as special certification for nondestructive testing, so in the general sense, no special certification is required. For anyone performing maintenance, §43.13 states in part "...He shall use the tools, equipment, and test apparatus necessary to assure completion of the work in accordance with accepted industry practices..." So when doing the inspection or test, you have to use the appropriate equipment and procedures in accordance with "accepted industry practices."
As A&P mechanics, we get our authority to perform maintenance from Part 65. §65.81 states in part that "...he 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."
In essence, the converse is true, if you’ve done a task in the past, you are certified to perform that task and return the item to service. If you’ve done a specific type of NDT inspection in the past, you can continue to do those inspections and return the part or aircraft to service following that inspection.
A repair station with an airframe or engine rating isn’t restricted from performing NDT work on those components for which they are rated. The FAA can also issue a limited rating for a repair station that only wants to perform nondestructive inspections, testing and processing. For a repair station to perform any function, there must be a training program in place, personnel that are properly trained, proper documentation, and the equipment must be calibrated to the satisfaction of the FAA.
Industry certification for NDT is controlled by one of three documents. These are Mil-Std-410 which has been superseded by NAS-410, ASNT-TC-1A, and ATA Specification 105. These documents deal with certification of individuals working for an organization that performs NDT functions. ATA Specification 105 takes the basic information from NAS-410 and ASNT-TC-1A and tailors it to meet only the requirements of an airline operating under FAR 121. This is the only one that is specifically targeting aviation. While the content of these documents are similar, there are differences.
FAA has accepted these documents as the basis for establishing training and qualifications for a limited rating for a repair station or for developing the NDT portions of an air carrier’s maintenance manuals. NAS-410 and ASNT-TC-1A establish the training and experience required for certification to their own standards. Each company is responsible to perform the training and document the necessary experience and vision testing to justify the certification of an individual working for that company.
Note that certification under NAS-410 and ASNT-TC-1A deal with an individual’s certification while working under the umbrella of a company-sponsored program. Also note that NAS-410 and ASNT-TC-1A are not FAA documents, and do not authorize an individual certificated under one of these programs alone, to return an aircraft to service.
Certification under NAS-410 or ASNT-TC-1A has three levels — Level I, II and III, and within each level, that certification is for a specific method of inspection. The methods listed are magnetic particle, liquid penetrant, radiographic, ultrasonic, visual and optical, and finally electromagnetic. Following is a brief description of the requirements and responsibilities for each level of certification.
Level I is an individual that is trained in a specific NDT method, has the skills and knowledge to perform specific tests, specific calibrations and, with prior written approval of the appropriate Level III individual, specific interpretations and evaluations for acceptance or rejection, as well as document the results in accordance with specific procedures. The individual shall be knowledgeable of any necessary preparation of parts before or after inspection. The individual shall be able to follow procedures in the techniques for which certified and shall receive the necessary guidance or supervision from a Level II or Level III individual.
Level II individuals shall have the skills and knowledge to set up and calibrate equipment, conduct tests, and to interpret, evaluate and document results in accordance with procedures approved by the appropriate Level III. The individual shall be thoroughly familiar with the scope and limitations of the method in which he is certified and capable of directing the work of trainees and Level I personnel. The individual will be able to organize and document NDI or NDT results. The individual shall be familiar with the codes, standards, and other contractual documents that control the method as utilized by the employer.
Level III individuals will have the skills and knowledge to interpret codes, standards, and other contractual documents that control the method as utilized by the employer; select the method and technique for a specific inspection; and prepare and verify the adequacy of procedures.
Only individuals certified to Level III shall have the authority to approve procedures for technical adequacy in the method to which they are certified. The individual shall also have general knowledge of all other NDI or NDT methods utilized by the employer. The individual shall be capable of conducting or directing the training and examination of personnel in the method certified. The individual shall not conduct NDI or NDT for the acceptance of parts unless the demonstration of proficiency in this capability was included in the practical examination upon which, in part, the certification is based.
ASNT has gone one step further, they now have the ASNT Central Certification Program (ACCP). With the ACCP, ASNT has taken the company certification and changed it into an industry certification program. When an individual qualifies as an ACCP Level II or III (Level I is not offered), that certification is supposed to be recognized by all organizations that are members of the American Society of Nondestructive Testing (www.asnt.org). For individuals interested in the ASNT ACCP program, training and experience requirements can be found at www.asnt.org/certification/leveliii/pd-accp.pdf
Now, how does this fit into our world of aviation maintenance? As was stated earlier, only individuals or organization certificated by the FAA can return an aircraft to service. If we contract with an entity certified to NAS-410 or ASNT-TC-1A to perform an NDT function on our aircraft, can they return that aircraft to service? In short, no, unless they are also an FAA-certified repair station or hold an A&P. Can you as an A&P return the aircraft to service following the inspection performed by someone else certified only under ASNT or NAS-410? Sometimes — if you can meet the requirements of §65.81, you can supervise the NDT inspection and return the aircraft to service.
Now that we are all thoroughly confused, let’s try and put this in some sort of perspective. If you are working on an air carrier aircraft, the work performed and the return to service has to be done in accordance with the approved air carrier maintenance manual. If that manual specifies certification for NDT personnel to Mil-Std-410 or NAS-410, than those are the guidelines that need to be adhered to. If the manual specifies ASNT-TC-1A, then that document is the guiding document, and if it says ATA Specification 105, then the ATA Specification is the guidance for development of NDT training and certification.
Repair stations may specify one of the above referenced documents for their method of training and certification of NDT personnel, or they may come up with their own training and certification program. It’s all about how the manual was written and accepted. Keep in mind, if an AD specifies ASNT or NAS-410 as the certification standard and a repair station has used some other standard for certification, that repair station is not authorized to perform the inspection even if they hold a limited NDT rating.
For A&Ps and IAs working on general aviation aircraft (not under an FAA-approved aircraft inspection program), the world of NDT is less clear. If the inspection is required by an airworthiness directive, that inspection has to be conducted within the framework of the AD. If the AD specifies that the inspection must be performed by someone certified under ASNT-TC-1A or NAS-410, then someone certified to those standards needs to perform the inspection.
Two examples of this are the wing strut AD on Taylorcrafts, and the AD on the forward wing attach fittings on Pawnees. The Pawnee AD requires the Ultrasonic inspections to be conducted by someone certified to at least a Level II under ASNT or Mil-Std-410. The dye penetrant inspections may be performed by an A&P with no NDT certification.
The Taylorcraft AD doesn’t specify the level of certification required for the ultrasonic or radiographic inspection, but Taylorcraft SB 2007-001 specifies a Level II or III certified by ASNT or NAS-410. Since this SB is incorporated by reference, the qualifications listed in the SB are mandatory. Note in both these examples, the NDT does not have to be performed by someone certified by FAA. That brings us back to the paradox of who returns it to service.
The standard practices portion of many maintenance manuals will specify the level of certification required for NDT inspections. Keep in mind that with few exceptions, maintenance manuals (Instructions for Continued Airworthiness) are not FAA-approved. The only section of a maintenance manual that is approved is the airworthiness limitations section, usually Chapter 4.
If the requirement for NDT certification is not contained in the airworthiness limitations section, but is somewhere else in the manual, FAA has made it clear that this is only advisory information. FAA Order 8620-2A. specifies in part that "the language of § 43.13(a) clearly provides a person with three permissible options when performing maintenance, alterations, or preventive maintenance on a product. Section 43.13(a) does not provide an order of precedence for these three options.
Further, although § 43.13(a) does not specifically address SBs or SLs, an OEM may legitimately incorporate an SB or SL into one of its maintenance manuals by reference. If it does so, the data specified, and the method, technique, or practice contained therein, may be acceptable to the administrator. However, unless any method, technique, or practice prescribed by an OEM in any of its documents is specifically mandated by a regulatory document, such as an AD, or specific regulatory language such as that in § 43.15(b); those methods, techniques, or practices are not mandatory."
If the maintenance manual for a given aircraft specifies the level and type of certification for NDT in an area other than the airworthiness limitations section, be very careful on the wording for the logbook entry if you don’t have the certification listed for the inspection performed. If you state that the inspection was performed in accordance with the maintenance manual, you are opening up a case for fraud.
On the other hand, if you state that the inspections were done only with reference to the sections that specify the procedures and exclude any sections that specify certification, you should be OK.
Anyone working on an aircraft that has a required Approved Aircraft Inspection Program (§91.409(f)), the content of that program determines the necessary NDT certification standards.
NDT inspections may be performed by an A&P, a repair station, an air carrier, or an organization certified by ASNT or under NAS-410. Only an A&P, repair station or air carrier can return an aeronautical product to service following this inspection.
If an aircraft is operated under an AAIP, or as an air carrier, the appropriate inspection program will determine the type and level of certification required for the given inspection. General aviation aircraft maintained under §91.409(a), (b), or (d) are only bound by the NDT certification requirements listed in an airworthiness directive, documents incorporated by reference into an AD, or those that may be listed in the airworthiness limitations section of the maintenance documentation.