A2LA Accreditation: Why It Matters for Aerospace Parts
- carystraley
- Jul 5
- 11 min read
Aerospace buyers do not accept a supplier's word that their measurements are accurate. They require proof, and A2LA accreditation is the most recognized form of that proof in North American precision manufacturing. Yet a surprising number of machine shops and calibration labs operate without it, leaving their aerospace customers to shoulder unquantified measurement risk on every inspection report. If your supply chain touches flight-critical components, structural assemblies, or high-tolerance fastener systems, the accreditation status of every lab that touches those parts matters more than most procurement teams realize.
Table of Contents
Quick Takeaways
Key Insight
Explanation
A2LA accreditation is ISO/IEC 17025-based
A2LA uses the internationally recognized ISO/IEC 17025 standard as the technical foundation for all laboratory accreditations, meaning accredited labs meet a globally accepted benchmark for measurement competence.
Accreditation is not the same as ISO 9001 certification
ISO 9001 covers quality management systems. A2LA accreditation specifically validates technical measurement competence and traceability to NIST, which is a much higher bar for metrology work.
Aerospace primes increasingly require accredited calibration sources
AS9100 Rev D and customer-specific quality requirements from OEMs like Boeing and Raytheon reference accredited calibration sources as the preferred or required standard for measurement traceability.
Accreditation covers specific scopes, not blanket capabilities
An A2LA certificate lists exactly which measurements and ranges a lab is accredited for. Buyers must confirm the lab's scope covers the specific parameters relevant to their parts.
Unaccredited inspection reports increase PPAP rejection risk
First article inspection and PPAP documentation backed by non-accredited measurement sources are frequently flagged during customer audits and can delay production launch approvals.
Metrology certification requires on-site technical assessments
A2LA sends trained assessors to physically evaluate lab personnel competence, equipment condition, environmental controls, and measurement uncertainty calculations, not just review paperwork.
SCPM's MetroLab division holds active A2LA accreditation
Summit City Precision Machining's in-house MetroLab provides A2LA-accredited calibration and CMM-based inspection support, giving aerospace customers documented measurement traceability from the same facility producing their components.
What Is A2LA Accreditation?
A2LA stands for the American Association for Laboratory Accreditation. It is a non-profit, third-party accreditation body that evaluates testing and calibration laboratories against the requirements of ISO/IEC 17025, the international standard for laboratory competence. When a lab holds A2LA accreditation, it means an independent technical assessor has verified that the lab's personnel, equipment, procedures, and quality system all meet defined criteria for producing technically valid measurement results.
A2LA was founded in 1978 and is a signatory to the International Laboratory Accreditation Cooperation (ILAC) Mutual Recognition Arrangement. That means an A2LA-accredited test report is accepted in over 100 countries without re-testing. For aerospace and defense supply chains that cross international borders, this is not a minor point.
The accreditation is scope-specific. A lab does not get a blanket certification saying "we measure things accurately." Instead, the A2LA certificate lists specific measurement disciplines, parameters, ranges, and uncertainty values the lab has demonstrated competence in. If a calibration lab is accredited for dimensional measurement from 0 to 500 mm with a stated uncertainty, that is exactly what the certificate covers, nothing more.
How A2LA Accreditation Works
The accreditation process begins when a laboratory submits an application to A2LA, defining the scope of measurements it wants accredited. A2LA then assigns a technical assessor with relevant expertise, often a working metrologist or calibration engineer, to conduct an on-site assessment.
The On-Site Assessment Process
During the on-site visit, the assessor reviews the lab's quality management documentation, interviews technical personnel, examines measurement equipment calibration records, evaluates environmental controls such as temperature stability and vibration isolation, and observes actual measurement activities. The assessor checks whether the lab correctly calculates and expresses measurement uncertainty in accordance with the JCGM 100 (GUM) guidance document.
Findings that do not meet ISO/IEC 17025 requirements are issued as nonconformances, and the lab must provide corrective evidence before accreditation is granted. This is not a rubber-stamp process. Labs that run poorly documented uncertainty budgets or cannot demonstrate NIST traceability for their reference standards are denied accreditation or issued major findings that require significant remediation.
Annual Surveillance and Reassessment
A2LA accreditation is not permanent. Labs must undergo annual surveillance activities and a full reassessment every two years. Any change in key personnel, measurement scope, or equipment must be reported to A2LA and may trigger an interim review. This ongoing oversight is exactly what gives accreditation its credibility over a one-time certification audit.
Pro tip: When qualifying a calibration supplier, request their current A2LA certificate and scope of accreditation, not just a statement that they are "A2LA accredited." The scope document tells you whether their accreditation actually covers the measurement parameters relevant to your parts. Dimensional calibration accreditation does not automatically include pressure, electrical, or temperature calibration.
Why Aerospace Quality Standards Demand Accredited Labs
The aerospace and defense industry operates under some of the most demanding quality frameworks of any manufacturing sector. AS9100 Rev D, the aerospace quality management system standard, explicitly addresses measurement traceability and calibration in clause 7.1.5. It requires that measuring equipment be calibrated or verified at specified intervals, traceable to international or national measurement standards.
While AS9100 does not mandate A2LA accreditation by name, major aerospace OEMs and their Tier 1 suppliers increasingly do. Boeing's supplier quality requirements, Raytheon's supplier qualification documents, and Lockheed Martin's material review processes all contain language that either requires or strongly preferences calibration sources with demonstrated accreditation to ISO/IEC 17025. A2LA accreditation is the primary mechanism for meeting that requirement in the United States.
PPAP Documentation and Measurement System Analysis
For automotive and aerospace suppliers using the PPAP (Production Part Approval Process) framework, the measurement system analysis requirements in AIAG's MSA reference manual directly tie to calibration traceability. A gauge R&R study conducted with improperly calibrated equipment produces statistically invalid results. When a customer auditor traces back the calibration source for the CMM or height gauge used in a first article inspection, finding a non-accredited calibration provider is a serious finding that can invalidate the entire PPAP submission.
In practice, suppliers who use A2LA-accredited calibration sources experience significantly fewer audit findings related to measurement traceability. The certificate provides an auditable, third-party-verified chain of evidence that the instrumentation producing inspection data meets established measurement standards.
"Calibration without traceability is just a number. Traceability without accreditation is just a claim. Accreditation turns the claim into evidence." - Paraphrased from NIST guidance on measurement traceability, consistent with NIST Special Publication 960-12.
Calibration Laboratory Accreditation vs. ISO Certification
This distinction matters enormously, and many procurement professionals get it wrong. ISO 9001 certification is a quality management system standard. It demonstrates that an organization has documented processes, performs internal audits, and pursues corrective action. It says almost nothing about whether the organization's measurements are technically correct.
Calibration laboratory accreditation to ISO/IEC 17025 is fundamentally different. It evaluates technical competence, specifically the ability to produce measurements that are valid, traceable, and accompanied by correctly calculated uncertainty statements. A shop can hold ISO 9001 certification and still have calibration processes that produce systematically biased measurement results.
Why Both Matter but for Different Reasons
A precision machining supplier holding AS9100 Rev D certification demonstrates a quality management system built for aerospace. A calibration lab within that facility holding A2LA accreditation demonstrates that the measurement backbone of that quality system is technically sound. The two credentials address different layers of the same quality pyramid.
For customers sending aerospace components to a supplier, the question is not "are they certified?" but "are they accredited for the specific measurements supporting my parts?" Those are very different questions with very different answers.
Pro tip: If a supplier quotes you on aerospace inspection work and lists only ISO 9001 or AS9100 as credentials for their metrology, ask directly whether their calibration lab holds A2LA accreditation and request the scope. The absence of a clear answer is itself a data point.
What A2LA Accreditation Means for Metrology and Inspection
In the context of precision machined components, metrology certification through A2LA accreditation has direct operational implications. Every gauge, CMM, height gauge, surface plate, and reference standard used in inspection work must trace back to NIST through an unbroken chain of calibrated comparisons. The calibration provider at the end of that chain must demonstrate that their reference standards are calibrated by NIST directly or by an A2LA-accredited laboratory whose own standards trace back to NIST.
When an accredited lab performs calibration, they issue a certificate that includes the measurement results, uncertainty values, calibration procedures used, equipment identifiers, environmental conditions during calibration, and the traceability statement. This is not optional documentation. ISO/IEC 17025 section 7.8 defines mandatory content for calibration certificates.
CMM Programming and Accredited Inspection Support
Coordinate Measuring Machine (CMM) programming and operation benefits directly from accredited calibration environments. A CMM operating in a temperature-uncontrolled environment with uncalibrated reference artifacts produces data that looks precise but may be systematically wrong. A2LA-accredited labs maintain environmental controls, typically holding temperature to 20 degrees C plus or minus 0.5 degrees C in accordance with ISO 1 standards for dimensional measurement, and verify their CMM performance with calibrated reference artifacts whose uncertainties are known and documented.
For aerospace components with GD&T tolerances measured in tenths of a thousandth of an inch, that environmental discipline is not optional. It is the difference between a CMM report that reflects the actual part geometry and one that reflects the thermal expansion state of the part during measurement.
How SCPM MetroLab Applies A2LA Standards in Practice
Summit City Precision Machining's MetroLab division operates as an A2LA-accredited calibration and inspection resource embedded within the same Fort Wayne facility that produces precision machined components. This integration is significant. Most machine shops send tooling and gauges out to a third-party calibration house, introducing lead time, handling risk, and a potential gap between when calibration is performed and when inspection work happens.
At SCPM, the calibration loop is closed in-house. Gauges used for first article inspection and in-process measurement are calibrated against NIST-traceable reference standards maintained in MetroLab. The calibration records, uncertainty statements, and traceability documentation are immediately available when a customer requests PPAP documentation or a first article inspection report.
Cleanroom and Environmental Control for Sensitive Components
MetroLab's capabilities extend beyond standard dimensional calibration. The division supports cleanroom rental for sensitive component handling and CMM programming for complex aerospace and industrial geometries. For customers sourcing components that require controlled-environment inspection, this eliminates the need to qualify a separate third-party inspection lab and simplifies the supply chain documentation considerably.
Calibration Support for Customer-Owned Gauges
A common but underappreciated service is calibration of gauges that customers supply to a machining vendor for use during production. If a customer ships a set of go/no-go gauges to a machine shop for attribute inspection, the calibration status of those gauges during production is the customer's problem if they do not confirm it at delivery and periodically thereafter. SCPM's MetroLab can calibrate customer-furnished gauges on arrival and provide calibration certificates that become part of the part-level quality record. This is a practical detail that prevents audit findings during customer surveillance visits.
Common Mistakes When Evaluating Lab Credentials
The most common mistake procurement engineers make is treating any mention of accreditation as equivalent. A lab can claim to be "accredited" while holding credentials from bodies that do not operate under ILAC mutual recognition. Only accreditation from ILAC signatory bodies, of which A2LA is one, carries international acceptance. Accreditation from a non-ILAC body is essentially self-declared quality assurance with a certificate attached.
A second common mistake is failing to check the expiration date and scope currency of the A2LA certificate. A2LA accreditation certificates show an expiration date, and the scope of accreditation is a separate document that may be updated independently of the certificate. A lab that was accredited for CMM measurement three years ago may have changed its equipment or personnel since then. Checking the current scope on the A2LA public database takes less than two minutes and provides a current, authoritative answer.
A third mistake is assuming that A2LA accreditation at a parent company's location extends to a subsidiary or satellite facility. It does not. Each physical location must hold its own accreditation for its specific scope of work. A supplier with six facilities and A2LA accreditation at one of them is not an A2LA-accredited supplier for work performed at the other five locations.
Comparison of Lab Credential Options for Aerospace Suppliers
Credential Type
What It Validates
Aerospace Acceptability
A2LA Accreditation (ISO/IEC 17025)
Technical measurement competence, NIST traceability, measurement uncertainty, personnel qualifications, environmental controls, validated by independent on-site assessors under ILAC MRA
Accepted by AS9100, Boeing, Raytheon, Lockheed, and most Tier 1 aerospace customers. Preferred or required for calibration sources on flight-critical programs.
ISO 9001 / AS9100 Certification
Quality management system documentation, process controls, corrective action, customer focus, internal audits. Does not evaluate whether measurements are technically correct.
Required for suppliers. Does not substitute for calibration laboratory accreditation. Auditors will still ask for evidence of measurement traceability separately.
Internal Calibration Program (No Accreditation)
Internally controlled calibration with self-declared traceability. No independent verification of personnel competence, uncertainty calculations, or environmental controls.
Acceptable for non-critical applications. Frequently cited as a finding in aerospace and defense audits when used as the sole calibration source for inspection equipment on critical characteristics.
Frequently Asked Questions
What is the difference between A2LA accreditation and NADCAP approval?
NADCAP (National Aerospace and Defense Contractors Accreditation Program) covers special processes such as heat treating, chemical processing, welding, and non-destructive testing. A2LA accreditation covers testing and calibration laboratory competence under ISO/IEC 17025. They address different parts of the aerospace supply chain. A supplier can hold NADCAP approval for a special process while their calibration lab holds A2LA accreditation for measurement support. For dimensional inspection and metrology specifically, A2LA is the relevant credential. NADCAP does not cover standard dimensional calibration activities.
How long does it take to obtain A2LA accreditation?
In practice, the process from initial application to granted accreditation typically runs four to twelve months depending on the lab's state of readiness, assessor scheduling, and the complexity of the scope being applied for. Labs that have robust ISO/IEC 17025-compliant quality systems and well-documented uncertainty budgets before they apply move through the process faster. Labs that need to build their quality system from scratch while simultaneously pursuing accreditation routinely exceed twelve months. The A2LA application fee and annual surveillance fees are in addition to the internal preparation costs.
Can a machine shop's in-house calibration lab get A2LA accredited?
Yes, and this is exactly the model that SCPM's MetroLab represents. A machine shop's internal calibration function can pursue A2LA accreditation for its specific scope of dimensional, mechanical, or other measurement disciplines. The lab must operate as a functionally independent unit with its own documented quality system, even if it is physically within the manufacturing facility. A2LA assesses it on the same technical criteria as any standalone commercial calibration lab. The accreditation is location-specific and scope-specific, so the shop must define clearly what measurements it wants accredited.
Does A2LA accreditation cover CMM inspection reports, or only calibration?
A2LA accreditation applies to both calibration laboratories and testing laboratories. A CMM inspection function can be accredited as a testing laboratory under ISO/IEC 17025 if the lab applies for and demonstrates competence in dimensional measurement as a testing scope. This is distinct from calibrating the CMM itself. In practice, many precision machining facilities hold accreditation for calibration of their reference standards and gauges, while CMM inspection reports are supported by the traceability chain established through that accredited calibration program. Customers should confirm with their supplier exactly what scope is covered by the accreditation certificate.
What happens to inspection data if a calibration source loses its A2LA accreditation?
This is a question most suppliers never think to ask until an audit surfaces it. If a calibration provider loses its A2LA accreditation and the supplier used that provider's calibrations as the basis for inspection data on aerospace components, the traceability of that inspection data is compromised for the period when the provider was non-compliant. Aerospace customers may require re-inspection, hold review of affected lot records, or in severe cases, issue a containment action on any components still in service. Monitoring your calibration providers' ongoing accreditation status is not paranoia. It is standard supplier quality management.
How do I verify a lab's current A2LA accreditation status?
A2LA maintains a public online directory where any customer can search for a laboratory by name, location, or accreditation number and view their current scope of accreditation. The directory shows active, suspended, or withdrawn status in real time. The scope of accreditation document, available through the same search, lists every specific measurement parameter, range, and uncertainty value the lab is accredited for. Checking this directly rather than relying on a supplier's self-certification takes less than two minutes and provides authoritative, current information. Do not accept a photocopy of an old certificate as evidence of current status.
If you work in aerospace procurement, quality engineering, or supply chain management and have dealt with accreditation disputes or calibration traceability issues on a production program, share what you encountered and how it was resolved.
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