Buying Third-Party Inspection and NDT for Aerospace Parts

Updated October 14, 2026

What third-party inspection covers

Third-party inspection is measurement, testing or witnessing done by someone other than the shop that made the part, bought by you to add capacity, add capability or add independence. The usual purchases are dimensional inspection, first article support, nondestructive testing, source inspection at a supplier, and extra receiving inspection when your own dock is backed up.

For the engineering behind each measurement, see our library pages on inspection and metrology and nondestructive testing. This page is about buying the work.

Match the accreditation to the work

Check that the lab is accredited or approved for the exact method you are buying, not just that it holds a certificate. Accreditation is granted against a defined scope, and work outside that scope is not covered.

• ISO/IEC 17025. The competence standard for testing and calibration laboratories. An accreditation body issues a certificate that points to a separate scope document listing the parameters, ranges and measurement capability the lab is accredited for. The scope notes that actual uncertainty on a given job may be larger than the listed capability, so a tight tolerance still needs a check against the scope.
• Nadcap NDT. PRI accredits NDT facilities against the AC7114 audit criteria, with separate method checklists. Read the lab's Nadcap scope for the methods you need.
• Prime and program approvals. Many primes keep their own approved source lists for NDT and other special processes. Your quality clauses say whether Nadcap alone is enough or a prime approval is also required.
• A quality system. AS9100 or ISO 9001 certification shows the lab controls records, calibration and nonconforming work, but it does not prove method competence on its own.

The qualifying a new supplier guide covers how to document the approval in your own system.

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CMM layout inspection

A full layout inspection measures every characteristic on the drawing, including notes and general tolerances, and reports actual values. Ask for that scope by name, because a lab quoting critical features only will produce a much shorter report.

To get a usable layout, send:

• The drawing at the released revision and the 3D model if the drawing references it for undimensioned features
• The edition of ASME Y14.5 the drawing invokes, so position and profile are evaluated to the right rules
• Any datum setup or fixturing instructions your engineering group uses, so results compare with the supplier's data
• Characteristics you consider critical, and any decision rule for results near a limit
• Whether you want the CMM program and alignment saved for repeat lots

When a layout is settling a dispute between you and a supplier, give both parties the same inputs and ask the lab to record alignment, probe, number of points and part temperature. Then a disagreement can be traced to the measurement rather than argued.

AS9102 first article preparation by a third party

A lab can do the measuring and paperwork for an AS9102 first article, but the report still documents the manufacturer's production process. The maker supplies the material and process certs, confirms the part was made with production methods and signs for the content.

Third-party FAI support usually includes:

• Ballooning the drawing so every characteristic, note and flag note has a number
• Measuring each characteristic and entering actual results on Form 3
• Building Form 1 and Form 2 from the part data and the certs the manufacturer provides
• Flagging characteristics that could not be measured nondestructively, so they can be verified another way

Tell the lab whether you need a full or partial FAI and which baseline report a partial updates. The first article inspection guide explains the forms and triggers, and the FAI review checklist is a list to review the finished package against.

NDT by method from accredited labs

Order NDT by method, practice document and acceptance criteria, and pick a lab whose accreditation covers that method. The method decides which Nadcap checklist applies, what the lab needs from you and what drives the schedule.

For CT, ASTM E1570 sets minimum requirements for fan beam CT examination and calls for a detailed procedure approved by the cognizant engineering organization. Like the other method practices, it does not tell the inspector what to reject. Acceptance criteria have to come from your drawing, specification or program document, so put them on the order.

NAS 410 personnel certification

Ask who will inspect and accept your parts, and check their certification for that method and level. NAS 410 sets the qualification and certification requirements for aerospace NDT personnel, and EN 4179 is the European counterpart written to the same purpose.

Certification under NAS 410 is issued by the employer through its written practice, not by a central body, so the evidence is in the lab's own records. When you approve a lab, ask for the written practice and the certification records of the people who will sign your reports, and confirm that interpretation and acceptance are done at the level your procedure requires. Confirm the current revision of NAS 410 your contract invokes. Our NDT library page describes what each level may do.

Source inspection on behalf of the buyer

Source inspection puts an inspector at the supplier's plant before the hardware ships. It is worth paying for when parts are large, expensive, hard to pack or ship twice, or when the contract sets witness points.

ISO 9001 clause 8.4.3, which AS9100 builds on, expects an organization to tell its external providers about verification activities it or its customer intends to perform at their premises. In practice that means the source inspection requirement belongs on the purchase order, not in a phone call the week of shipment. Government contracts can add their own source inspection: FAR 46.402 directs agencies to perform quality assurance at source in cases such as when inspection elsewhere would need uneconomical disassembly, destroy costly special packing, or rely on instruments available only at the source.

Define the inspector's job in writing:

• Which characteristics, tests or records to witness or review
• Whether the inspector may accept, or only report and hold for your decision
• How much notice the supplier must give before the inspection point
• What happens to the schedule if the inspection finds a problem

Receiving inspection overflow

When your dock is backed up or a lot needs checks you cannot run, a lab can perform receiving inspection to your procedure. The lab should work to your plan, not invent its own.

• Name the sampling plan your receiving procedure uses and the characteristics to check
• Send the PO, drawing revision and certificate requirements so paperwork is reviewed alongside the parts
• State whether the lab records results only or also recommends a disposition
• Agree how parts are identified, segregated and returned so lot integrity is kept

The receiving inspection checklist is a list you can hand to an outside lab as the scope of work.

Reports and data packages

An inspection report is only useful if someone else could repeat the work from it. Specify the contents before the job starts.

• Part number, revision, serial or lot, and quantity inspected
• Method, practice document and revision, procedure or program number
• Instrument or equipment identification and calibration due dates
• Acceptance criteria applied and actual results, not just accept or reject
• For NDT, the technique, sensitivity or class, and the inspector's name, method and level
• For CMM, alignment, datums simulated and the Y14.5 edition interpreted
• Nonconformances found, with images where they help
• Signature and date of the person releasing the report

If your system needs a specific file format, a native CMM file, or images and CT volumes delivered electronically, say so on the order. Large data sets take time to package and transfer.

What drives turnaround

Setup and preparation usually take longer than the inspection itself. A first lot of a new part costs the most time, and repeat lots go faster once programs, techniques and fixtures exist.

• Programming and technique work. A new CMM program, UT technique or CT setup has to be built before the first part is measured.
• Reference standards. UT and ET need reference standards that may have to be made or borrowed.
• Missing inputs. No acceptance criteria, no model, or an unclear revision stops work until engineering answers.
• Part condition. Machined parts may need etching before penetrant to remove smeared metal, and most methods need clean parts.
• Quantity and sampling. Full layout on every part takes far longer than a sample.
• Approvals. Prime approvals or witness points narrow the choice of labs and add scheduling.

We do not promise turnaround. A person reviews each request and replies within one business day, and rush requests are prioritized. Our special processes cost guide covers how outside processing adds to cost.

What to put on the PO

Write the order so the lab cannot misread the scope and your quality group can accept the report without a phone call.

• Service: full layout, critical features only, FAI preparation, NDT method, source or receiving inspection
• Drawing number and revision, model revision and Y14.5 edition
• Method practice documents with revision, sensitivity or class, and acceptance criteria
• Accreditation required: ISO/IEC 17025 scope, Nadcap method, prime approval
• Personnel certification required for NDT, with method and level
• Sampling plan, quantity and serial or lot identification
• Report contents and data format
• Hold or release authority for source inspection
• Record retention and your right to review the lab's records
• Export control status of the drawing or model

The PO quality flow-down template gives clause wording you can adapt. Drawings for ITAR or CUI programs should follow our controlled programs page.

How Aerospace Sourcing handles inspection work

We are a sourcing service, not a lab. We do not own CMMs or NDT equipment. We match your inspection scope to providers whose accreditation and approvals cover the methods you need, and manage the job through delivery of the report.

• One quote, one lead time, one point of contact and one purchase order, even when dimensional and NDT work go to different labs
• Your methods, acceptance criteria, accreditation and personnel requirements flowed down in writing
• Reports checked against the drawing, the PO and the requested content before release to you
• A certificate of conformance with every order, plus the inspection reports your request calls for

If the parts also need to be made, inspection can be built into a machining, fabrication or special process order from the start.

Request inspection or NDT

Send the drawing, the inspection scope, quantities and acceptance criteria through the inspection request form. It is preset for inspection, so it asks for the method, the accreditation you require and the report you need, which are the details that decide which labs can take the work. A person replies within one business day. Files are shared under a mutual NDA, as described on our confidentiality page.

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Send the job. A person replies within 1 business day.

Part, quantity and date are enough to start. Drawings and the mutual NDA follow by reply, and controlled programs never send technical data through this site.

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Questions

Related

• AS9102 First Article Inspection: A Buyer's Guide
• Buying Aerospace Special Processes the Right Way
• What Is a Certificate of Conformance in Aerospace?
• Aerospace Hardware Sourcing With Traceability

Sources

• Omnex: Nadcap AC7114 NDT requirements course, list of method checklists
• SAE: AS7114 Nadcap requirements for nondestructive testing
• PRI: Nadcap program overview
• ASTM: E1570-19 standard practice for fan beam computed tomographic examination
• ASTM: E1417/E1417M liquid penetrant testing
• BSI: EN 4179 aerospace series, qualification and approval of personnel for NDT
• ATS: NAS 410 training and certification levels
• Acquisition.gov: FAR 46.402 Government contract quality assurance at source
• Auditor Training Online: ISO 9001 clause 8.4, information for external providers
• Mettler-Toledo Rainin: example ISO/IEC 17025:2017 scope of accreditation
• ASME: Y14.5 dimensioning and tolerancing
• InspectionXpert: AS9102 first article inspection