Written Practice Development for Aerospace Manufacturing and Repair Stations

What a written practice actually is, and what it is not

A written practice is the employer's own law on personnel qualification. It is the document that says how this company decides someone may perform, interpret, evaluate and accept nondestructive examination, and it is the reason a certificate issued in your name means anything. Every report your organisation signs is downstream of it. If the practice is weak, the certificates are weak, and every examination record they support inherits that weakness.

It is not a copy of SNT-TC-1A with your logo on it. SNT-TC-1A is a recommended practice written to be tailored; it deliberately leaves choices to the employer, and a document that simply reproduces its tables has made none of those choices. Auditors recognise the pattern instantly, because the giveaway is the word 'recommended' surviving into a document that is supposed to be mandatory inside your building.

It is also not the training programme. The practice sets requirements; the training programme, the examination bank, the specimen library and the records system deliver them. Keeping them as separate controlled documents that reference each other is far more maintainable than one enormous file, and it lets you revise a question bank without triggering a review of the whole certification scheme.

SNT-TC-1A, CP-189 and NAS 410: choosing which one controls

SNT-TC-1A gives you the most flexibility and the most responsibility: you set the hours, the examination content and the intervals, and you must be able to justify them technically. CP-189 is a standard rather than a recommendation, with fixed requirements and a named certifying-agency structure, and it is the right choice where a customer or an accreditation body demands less employer discretion. Some organisations run CP-189 because it removes the argument about whether their tailoring was reasonable.

NAS 410 sits over both in aerospace. It is invoked contractually by primes and OEMs, it uses mandatory language, and it sets floors for training, experience and examination that the employer may exceed but not cut. The practical consequence is that an aerospace written practice is usually SNT-TC-1A in structure and NAS 410 in numbers, and the document needs an explicit statement of that hierarchy near the front so nobody has to reverse-engineer it from the tables.

ISO 9712 enters where the organisation also works to European or international customer schemes. It is a third-party certification model, not an employer-based one, and mixing it into an employer written practice without stating the boundary produces genuine confusion about who certified whom. If you hold both, say which certificates come from which scheme and what each is accepted for.

The content list, and the parts people leave out

Most written practices cover scope, methods, levels, training, experience, examination and recertification. The omissions are consistent. Limitations are the first: the practice allows a certification to be restricted to a technique, product form or customer, but never explains how a limitation is recorded on the certificate or enforced when work is assigned. The second is suspension and reinstatement — what happens when a technician fails a re-examination, misses a vision check, or is away from the method for a long period.

The third omission is the outside agency Level III. Many aerospace suppliers use one, and it is entirely legitimate, but the practice must name the arrangement, define what the outside Level III may approve and sign, and describe how continuity is maintained when they are not on site. An agreement in a contract file that is not reflected in the written practice does not close the loop.

The fourth is records: who holds them, in what form, for how long, and what happens on personnel departure. An aerospace customer may ask for a technician's file years after the person left. If retention is undefined, the answer becomes 'we think we have it', which is the same as not having it.

Who owns the document: the Level III of record

A written practice needs a named technical owner. That is the Level III of record — the person who approves the practice's technical content, approves procedures written under it, administers or authorises examinations, and signs certifications. Quality can own the revision mechanics. The technical content cannot be owned by someone who is not qualified to defend it, because that is exactly what happens in an audit.

The role has continuity requirements that companies underestimate. If your only Level III resigns, every certification issued from that date forward has no valid certifying authority until the gap is closed, and the practice should say what the interim arrangement is. Naming a role and maintaining a current signature-authority record — with the Level III's own certification attached — turns a personnel event into a paperwork event rather than a systemic finding.

There is a boundary worth stating plainly inside the document, because it is routinely blurred. The technician performs and evaluates within their certified level. The Level III approves the procedures the technician works to, and the practice itself. Neither of them is the person who releases the article to service; in a repair station that authority sits elsewhere, and a written practice that implies otherwise creates a regulatory problem, not just a technical one.

What an auditor samples, in the order they do it

Audits of personnel qualification follow a well-worn route. The auditor reads the practice quickly to find the requirements you set for yourself, because those become the standard they measure you against. Then they pick individuals — usually two or three, spread across methods and levels, and often deliberately including someone whose certificate is close to expiry or carries a limitation.

For each individual they trace the chain: training hours to a course record with an outline and an instructor; experience hours to something that resembles real work rather than a round number; general, specific and practical examination scores to marked papers; the practical to a physical specimen with a documented answer key and a recorded grading; vision to a dated record within the required interval. Any link that cannot be produced is a finding, and a missing link in two of three files is a systemic finding rather than an isolated one.

The last move is the one that hurts. They pull a signed examination report from production and check whether the person who signed it held the level, method and scope the practice requires for that work on that date. A single report signed outside a certification limitation calls the whole assignment control system into question, and the corrective action is rarely small.

The drift that quietly invalidates certificates

Written practices almost never fail because the policy was wrong on the day it was written. They fail because the organisation moved and the document did not. The clearest example is the revision that raises a requirement without a transition plan: the new revision requires more experience hours in a method, existing certificates were issued under the old rule, and nothing in the file records the decision to carry them. An auditor cannot tell the difference between a considered decision and an oversight unless you wrote it down.

Experience accounting is the arithmetic trap. Where a scheme requires minimum hours in a specific method, total NDT hours cannot be substituted, and classroom training hours are not experience. Multi-method technicians produce genuinely difficult accounting, because a shift spent on a job involving three methods cannot be counted three times. A practice that defines the accounting rule explicitly — and a log that follows it — turns the hardest question in the audit into a two-minute answer.

Training-record signature drift is the other constant. The practice says the Level III verifies training; in reality a busy shop has the shift supervisor sign because the Level III is on another site. Six months later there are forty records with the wrong signature. The fix is procedural — a documented delegation, or a realistic verification step the Level III can actually perform remotely and sign for.

How the aerospace regime changes what 'adequate' means

A general-industry written practice is adequate when it is internally consistent and defensible. An aerospace one has to survive readers who arrive with their own checklist. A Nadcap NDT audit reads against the AC7114 criteria and the method-specific criteria beneath it, and it is unusually specific about evidence: not whether you have a procedure, but whether the file shows the technique was qualified and the personnel were qualified to run it.

An FAA-certificated repair station adds a second regime. Part 145 requires an employee training programme, and the NDT written practice has to sit coherently inside the repair station manual and training programme rather than beside it as a separate universe. Auditors from the two worlds ask different questions about the same file, and the practice needs to answer both without contradiction — including on records retention, where regulatory and customer expectations can differ.

Finally, the OEM or prime supplier quality requirements can add content that neither ASNT nor NAS 410 anticipated: named specimen types, customer-witnessed practicals, approval of individual technicians by name for particular part families. These flow-downs belong inside the written practice or in a controlled appendix, because a requirement that lives only in a purchase order will be missed the moment the person who negotiated it changes job.

Rebuilding a written practice without invalidating what you already have

Most engagements start with a practice that is not wrong so much as unevidenced. The right sequence is to gap the existing document against SNT-TC-1A or CP-189 and NAS 410 first, then gap the files against the existing document, because those are two different problems with two different corrective actions. Fixing the document while the files still fail simply moves the finding.

From there the work is: rewrite the practice with explicit hierarchy and honest requirements you can meet; build a transition matrix showing what happens to every current certificate under the new revision; rebuild the examination bank and the practical specimen library with documented keys; and reconstruct the experience accounting rule so it can be applied consistently going forward. Where historical records genuinely cannot be reconstructed, the defensible answer is a documented re-examination, not a backdated file.

This work is additive by design — nothing already valid is discarded, and existing certifications are carried wherever the evidence supports it. Atlantis acts as NDT technical authority for the rebuild: practice development, procedure approval, personnel certification within the practice, and representation on technical questions when the auditor is in the room. Affordable, accessible and fully customisable. Ask for a consultation or a scoped quote at info@atlantisndt.com.

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