What Is NADCAP Special Process Accreditation and Why Does It Matter?

If you work in aerospace, defense, or any industry that supplies critical safety parts, you’ve likely heard of NADCAP. But what exactly is a "special process," and why does NADCAP accreditation carry so much weight? This article explains the core concept, how the accreditation system works, and what it means for your quality management system.

What It Is

NADCAP (National Aerospace and Defense Contractors Accreditation Program) is a global accreditation scheme managed by the Performance Review Institute (PRI). It provides standardized, consensus-based accreditation for special processes—manufacturing or testing operations whose results cannot be fully verified by subsequent inspection or testing. Examples include heat treating, welding, brazing, non-destructive testing (NDT), chemical processing, and surface enhancement.

Because these processes are "special," defects may not be visible until part failure in service. NADCAP accreditation gives aerospace primes and their suppliers confidence that a facility performs these processes consistently to industry standards (e.g., AC-7004 for aerospace quality systems, plus specific process audit criteria published by PRI).

How It Works: The Accreditation Process

NADCAP accreditation is not a one-time certificate. It follows a structured, recurring cycle:

1. Self-assessment – The supplier reviews its own process documentation, personnel qualifications, and equipment against the applicable PRI audit checklist.
2. On-site audit – A PRI-appointed, technically qualified auditor visits the facility. The audit covers process control, calibration, traceability, and compliance with customer and industry specifications.
3. Checklist-based scoring – The auditor uses a detailed checklist (e.g., for heat treating or NDT) that defines "major" and "minor" nonconformances. Major findings typically require corrective action before accreditation is granted.
4. Corrective action – The supplier must submit root cause analysis and evidence of correction within a defined timeframe.
5. Accreditation decision – PRI issues accreditation for a specific process scope, usually valid for 12–24 months, after which a re-audit is required.

The key principle: compliance is verified against the audit checklist, not just against your own internal procedures. The checklist is the authoritative reference for what the auditor will examine.

A Worked Illustrative Example

Example data (illustrative only):

Imagine a metal finishing supplier seeking NADCAP accreditation for chemical processing (anodizing). The auditor uses the PRI Chemical Processing checklist. During the audit, they verify:

• Tank solution concentration – records show bath chemistry checked every 8 hours, within ±5% of specification.
• Temperature control – the tank temperature chart shows 21°C ± 2°C over the last 30 days.
• Part cleaning sequence – the operator follows the written work instruction, and the sequence matches the approved process specification.
• Calibration – the pH meter used is calibrated with a certificate traceable to NIST, dated within 90 days.

The auditor finds one minor nonconformance: the log for the last tank change was not signed by the shift supervisor. The supplier corrects the documentation, submits evidence, and receives accreditation for a 24-month period. Six months later, a customer audit finds the same facility's welding process is not NADCAP accredited—so the customer requires the supplier to either outsource that welding or pursue a separate NADCAP scope.

This example shows that NADCAP is process-specific, not company-wide. A facility can be accredited for one process and non-accredited for another.

Common Pitfalls

• Treating NADCAP like ISO 9001 – NADCAP is far more technical and process-specific. A generic quality manual will not pass an audit.
• Ignoring checklist updates – PRI revises checklists periodically. Auditors use the current version, so your internal audit must track revisions.
• Relying on "we've always done it this way" – If a practice contradicts the checklist or the customer specification, it is a finding, regardless of your historical performance.
• Poor corrective action – NADCAP expects root cause analysis, not just a fix. A superficial response often triggers a follow-up audit or delays accreditation.

Closing Note

NADCAP accreditation is a rigorous, valuable signal of process capability in aerospace manufacturing. Whether you are preparing for your first audit or maintaining an existing scope, the audit checklists are your most reliable guide—not hearsay or internal habits. To streamline your preparation and track audit findings, you can use a structured quality tool designed for process audits. Try the free NADCAP special process tool at https://www.6sq.com/tools/nadcap/ to organize your checklist compliance and corrective actions.