A&P Mechanics, IAs and NDT

Two different kinds of qualification

In U.S. aviation maintenance, the mechanic certificate with airframe and powerplant ratings (the A&P) and the Inspection Authorization (IA) are FAA credentials issued under 14 CFR Part 65. They define who may perform maintenance, who may carry out required inspections and who may approve an aircraft for return to service.

NDT certification is a different thing. It is method-specific — eddy current, ultrasonic, penetrant, magnetic particle, radiography — and is issued by an employer under a written practice that follows a recognized standard such as NAS410 (Level 1, Level 2 and Level 3) or ASNT SNT-TC-1A (Level I, II and III), or the airline-oriented guidelines of ATA Specification 105. It says that a person has the training, experience, vision and examination results to perform and interpret a particular inspection method.

The two often meet in the same person, but one does not imply the other. Part 65 does not treat an A&P certificate or an IA as a qualification in any NDT method.

What the regulations say, in plain English

A few rules shape how NDT fits into general aviation and repair station work. This is a summary, not legal advice; read the current text on the eCFR.

• Part 65 (mechanics). A certificated mechanic may perform or supervise maintenance and alterations on what they are rated for, and an airframe or powerplant rating lets them approve that work for return to service (major repairs and major alterations excepted) and perform 100-hour inspections. Part 65 also limits these privileges: a mechanic may not supervise or approve work they have not satisfactorily performed before, unless they first show the ability to do it, and must understand the manufacturer's current instructions and maintenance manuals for the task.
• Part 65 (Inspection Authorization). An IA holder, who must hold both ratings and meet experience and testing requirements, may perform annual inspections, perform or supervise progressive inspections, and approve major repairs and major alterations done to approved data for return to service.
• Part 43 (performance rules). Anyone doing maintenance must use the methods in the current manufacturer's maintenance manual or instructions for continued airworthiness, or other methods acceptable to the FAA, and must use the tools, equipment and test apparatus needed to do the job to accepted industry practice — including special equipment the manufacturer recommends, or an acceptable equivalent. Annual and 100-hour inspections must be done with a checklist covering at least the scope in Part 43's Appendix D.
• Part 91. Most aircraft need an annual inspection every 12 calendar months, and aircraft used for hire also need 100-hour inspections, unless they are on another approved inspection program.
• Part 145 (repair stations). Repair stations must keep inspection personnel familiar with the inspection methods and proficient with the equipment they use, and must run an FAA-approved training program. The FAA can issue a limited rating specifically for nondestructive inspection, testing and processing, and a repair station with a limited rating for specialized services lists the specification it works to in its operations specifications.

What FAA guidance adds

Advisory Circular 43.13-1B, the familiar reference on acceptable methods, techniques and practices, has a chapter on nondestructive inspection. In summary, it makes three points relevant here. The NDI method and procedure are generally specified by the manufacturer or the FAA — in maintenance and overhaul manuals, airworthiness directives, supplemental structural inspection documents and service bulletins. The effectiveness of any NDI method depends on the skill, experience and training of the person performing it. And the people who detect and interpret indications in methods such as eddy current, radiography and ultrasonics should be qualified and certified to recognized government or industry standards; the circular names MIL-STD-410, a military personnel standard since cancelled with NAS410 as its usual replacement, and ATA Specification 105 as examples.

An advisory circular is guidance rather than regulation, but it describes what the FAA considers acceptable practice — which is the standard Part 43 asks mechanics to work to.

Who performs, who signs

In practice, the arrangement in most well-run shops looks like this:

• Visual inspection, including borescope inspection of cylinders and engine sections, is part of the everyday work of A&P mechanics and IAs, performed to the manufacturer's instructions.
• Formal NDT methods called for by maintenance data — eddy current of wheel halves or bolt holes, ultrasonic thickness or crack checks, penetrant or magnetic particle inspection of landing gear, engine mounts and engine parts — are performed by a person qualified and certified in that method, whether that is an in-house technician under the shop's written practice or an outside NDT provider or repair station.
• The A&P or IA reviews the NDT report, confirms that the inspection matched what the maintenance data or AD required, dispositions any findings, and makes the maintenance record entry and return-to-service decision within their own privileges.

Many A&Ps also hold NDT certifications, which is valuable, but the two credentials are held and kept current separately. Where an operator's program, a repair station manual, a manufacturer's document or an airworthiness directive states its own personnel qualification requirement for an NDT task, that requirement governs; read the document, because they differ.

Where NDT shows up in annuals, 100-hours and ADs

The Appendix D scope of an annual or 100-hour inspection is largely visual and functional. NDT enters through the other documents the inspection has to account for:

• Manufacturer inspection programs may include NDT tasks at set intervals or conditions, such as eddy current of wheel halves at tire changes or penetrant inspection of specific fittings.
• Airworthiness directives on some aircraft, engines and propellers call for eddy current, ultrasonic or other NDT of specific structure — wing spar attach areas on some light aircraft are a well-known example — often with repeat intervals. Checking AD compliance status is a routine part of the annual.
• Findings during a visual inspection, such as a suspected crack or corrosion, often lead to NDT to confirm and size the damage before a repair decision.
• Overhauls of engines, propellers and components include NDT of parts as the overhaul data requires, usually performed by the overhaul facility.

Keep the NDT report with the aircraft records. The logbook entry says the inspection was done; the report shows what was inspected, how, by whom and with what result.

What this means for mechanics, IAs and owners

For A&Ps and IAs, a few habits pay off: read the NDT requirement in the source document before arranging the work; confirm the NDT provider is certified in the specific method and technique, and that equipment calibration and reference standards are current; make sure the report identifies the procedure used and the person's certification; and question a report that does not match what the data required.

For aircraft owners, ask who will perform any required NDT and how they are qualified, and make sure the report comes back with your records. For repair stations, an NDT capability — or a limited rating — brings a written practice, procedures, training, a Level 3 (in-house or outside) and records that will be looked at closely.

How NDT LLC can help

NDT LLC supports maintenance shops, repair stations and IAs with NDT program setup and written practices, procedures developed from manufacturer data, training and certification of technicians under NAS410 and related standards, outside Level 3 services, and independent review of NDT reports and vendors. Contact us to talk through your shop's NDT needs.