NADCAP Welding Audit: Requirements and Quality Documentation

NADCAP welding accreditation is a mandatory prerequisite for supplying flight-critical welded components to Boeing, Airbus, GE Aviation, Pratt & Whitney, and most aerospace primes. Unlike ISO 3834 certification — which can be self-declared or third-party certified — NADCAP requires an auditor from PRI (Performance Review Institute) to physically witness welding operations and verify every item on the AC7110 checklist.

This guide covers what auditors actually check, where suppliers consistently fail, what documentation records are non-negotiable, and how real-time thermal monitoring provides objective evidence for NADCAP compliance.

What Makes Welding a Special Process

NADCAP defines a special process as one whose results cannot be fully verified by subsequent inspection or testing without destructive evaluation. Welding fits this definition precisely: a joint that passes visual inspection, dimensional check, and radiographic testing may still contain hydrogen-induced cracking that emerges hours later, or fusion defects undetectable by the selected NDT method.

Because post-process verification is inherently incomplete, NADCAP shifts the compliance burden to process control: if the inputs — WPS parameters, qualified welder, certified consumables, calibrated equipment, controlled environment — are demonstrably correct, the output is presumed conformant within the limits of the governing acceptance standard.

Other NADCAP special processes include heat treatment, chemical processing, non-destructive testing, and coatings. Welding accreditation is governed by AC7110/1 (fusion welding) and AC7110/4 (resistance welding). The fusion welding checklist covers GTAW, GMAW, PAW, EBW, LBW, and SMAW; processes such as friction stir welding and brazing fall under separate checklists.

AC7110 Audit Scope: What Auditors Check

The NADCAP AC7110/1 checklist is publicly available on PRI eAuditNet and covers eight primary audit domains:

Common Audit Failures and Their Root Causes

Recurring NADCAP findings across aerospace Tier 1 suppliers fall into four high-frequency categories:

WPS/PQR Range Gap

The most common critical finding: a production weld performed outside the qualified range of the applicable WPS. Typical scenarios include base material thickness outside the qualified range per ASME Section IX or AWS D17.1, joint design not covered by the PQR coupon, or a shielding gas mixture outside WPS limits.

Root cause: WPS library not updated as production parameters evolve. Fix: WPS applicability review at job setup, documented on the traveler before arc start.

Consumable Traceability Break

The traveler references a wire lot but the heat number is missing or references an expired certificate. In NADCAP, heat number traceability from mill cert to weld traveler is non-negotiable for all classified filler materials.

Root cause: consumable issuance process disconnected from traveler generation. Fix: kitting system that records heat number at the point of issuance.

Equipment Calibration Lapse

A calibrated instrument (current meter, gas flow meter, heat input monitor) with an expired calibration sticker invalidates every weld produced after the calibration expiry date — retroactively. The auditor will request calibration records for all equipment used in production and cross-reference expiry dates against the weld production log.

Root cause: calibration due dates managed in a spreadsheet disconnected from the production schedule. Fix: integrate calibration alerts with work order release.

Welder Continuity Record Gap

AWS D17.1 and most prime-specific standards require evidence of process continuity every six months. A welder who performed no qualifying production welds during a six-month window may need to re-demonstrate qualification.

Root cause: HR qualification records not cross-checked against production traveler data. Fix: quarterly continuity audit comparing qualification records against weld logs.

Documentation Records That Must Survive Audit

Beyond the traveler, auditors expect to trace a finished weld back through the entire supply chain. A complete NADCAP-compliant document chain includes:

1. Purchase order and drawing — specifies applicable code, quality level, and customer-specific requirements
2. Welding Procedure Specification (WPS) — links to PQR, defines all essential and supplementary variables per governing standard
3. Weld traveler — weld map, WPS reference, welder ID, consumable heat number, date, parameter log, inspector sign-off
4. Welder qualification record — current, covering process, position, and thickness range matching production
5. Consumable cert of conformance — heat number, chemistry, and mechanical properties per AWS A5-series or EN 14295
6. Equipment calibration records — traceable to NIST or a national metrology body, with current expiry dates
7. Environmental monitoring log — temperature, relative humidity, and dew point for classified welding environments

How Real-Time Monitoring Strengthens NADCAP Evidence

Manual heat input logging — the operator recording voltage, amperage, and travel speed at intervals — creates transcription risk and gaps during complex multi-pass sequences. Auditors increasingly expect electronic records with timestamps tied to welder ID and weld identifier.

Real-time thermal monitoring addresses three documentation gaps that routinely trigger NADCAP findings:

Heat input traceability per weld ID. Continuous current and voltage logging linked to the weld traveler number produces an immutable record of actual heat input per pass — not an operator-estimated entry subject to recall error. For processes with a maximum heat input limit in the WPS (common in high-strength steel and austenitic stainless fabrication), this constitutes objective compliance evidence.

Preheat and interpass temperature per weld. Thermocouple-based temperature records require manual placement and manual entry. An infrared monitoring system captures a continuous temperature field across the joint, automatically timestamped and stored per weld ID — satisfying ISO 13916 traceability requirements without manual intervention.

Arc-on/off time and sequence. Some AC7110 checklist items require demonstration that maximum interpass time limits were observed. An electronic arc-on log with timestamps provides this evidence automatically, without requiring the welder or inspector to record it separately.

NADCAP Accreditation Path

For a supplier pursuing NADCAP welding accreditation for the first time, the typical sequence is:

1. Register on PRI eAuditNet and download the current AC7110/1 task list. The task list is the definitive audit instrument — every checklist item must have an owner and a documented response.
2. Conduct internal self-assessment against all task list items. Assign closure owners and target dates to each gap. Typical preparation window: 4 to 8 weeks.
3. Prioritise critical gap categories first: WPS/PQR coverage completeness, calibration currency, and traveler format correctness are the highest-NCR categories in first-time audits.
4. Request an audit through eAuditNet. PRI assigns the auditor; suppliers cannot select or influence the assignment.
5. On-site audit (1 to 3 days): documentation review, live witnessing of welding operations, equipment inspection, and record spot-checks.
6. Close NCRs within the timeframe specified in the audit finding. Objective evidence — updated procedures, corrected records, photographs — is required. Narrative responses alone are not accepted.
7. Accreditation granted for 12 months, renewable through surveillance audits. Consistent compliance history supports extension to Merit status (longer audit intervals).

Suppliers already certified to ISO 3834 or AS9100 have transferable management system infrastructure. The gap to NADCAP is primarily documentation format (especially consumable heat number traceability and environmental control records) and the audit-facing evidence package. Reviewing your WPS documentation process against AC7110 scope before the self-assessment is the single highest-leverage preparation step.