AS9102 First Article Inspection: Keeping FAIs Valid After Changes

Engineering change orders are a normal part of hardware production, but in aerospace and defense programs, every revision creates an immediate compliance headache. You release an updated CAD model, increment the drawing revision from Rev A to Rev B, and the production line suddenly faces a verification roadblock. The original AS9102 first article inspection report, which took weeks of coordinate measuring machine programming and manual ballooning to compile, is no longer aligned with the released definition.

Quality and manufacturing engineers are then stuck answering a difficult question: does this design change trigger a completely new FAI, or will a partial delta FAI suffice? Scoping this incorrectly creates friction. Over-inspecting wastes thousands of dollars in inspection lab time and delays delivery schedules. Under-inspecting risks non-conformance penalties, rejected lots, and failed customer audits.

This guide shows you how to maintain FAI validity across design revisions. Follow these five steps and you can evaluate design modifications systematically, scope delta FAIs defensibly, and trace engineering changes directly to quality verification records before an auditor raises an objection.

Step 1: Understand What AS9102 Actually Requires: Form 1, Form 2, and Form 3

To evaluate the impact of a design change, you need to treat the AS9102 package as an interconnected data model rather than a static stack of paperwork. The aerospace standard, maintained by the International Aerospace Quality Group, distinguishes between full and partial FAIs and organizes reporting across three forms. Each form addresses a specific layer of manufacturing accountability.

Form 1 (Part Number Accountability) identifies the physical part, its subassemblies, the associated drawing revision, and the FAI type. When you execute an initial inspection, Form 1 registers as a baseline. When a design change occurs, Form 1 is the historical anchor. Field 14 identifies whether the report is a full or partial FAI, calling for the baseline part number, revision level, and reason for the inspection when completing a partial FAI.

Form 2 (Product Accountability) tracks raw material, special processes, and functional testing. If an engineering change switches an aluminum alloy from 6061-T6 to 7075-T7351, or updates an anodizing specification from MIL-A-8625 Type II to Type III, Form 2 is your point of failure. If the revision merely alters a hole diameter without touching materials or surface treatments, Form 2 remains valid and requires no re-verification.

Form 3 (Characteristic Accountability, Verification and Compatibility Evaluation) is where design changes cause the most churn. Form 3 records every single design characteristic, including dimensions, tolerances, geometric dimensioning and tolerancing (GD&T) callouts, drawing notes, and surface finish requirements. An aerospace drawing for an avionics enclosure or turbine component can easily contain 400 separate characteristics. A CAD update rarely invalidates all 400, but it inevitably changes the status of several. Maintaining validity means knowing precisely which Form 3 lines remain compliant and which must be reopened for measurement.

Step 2: Know the Triggers: When a Design Change Requires a Full or Partial FAI

AS9102 Section 4.6 defines the baseline triggers for repeating a first article inspection. The standard states that an organization must perform a full or partial FAI when a change occurs that affects fit, form, or function of the part. The IAQG 9102 FAQ notes that changes such as manufacturing-source, process, inspection-method, location, tooling, or material changes require an FAI depending on their potential effect on fit, form, or function.

A full FAI is mandatory in limited circumstances. A complete redesign or a move to a new facility may call for a full or partial FAI depending on the affected characteristics, while a two-year production lapse requires an update for characteristics potentially affected by inactivity, subject to customer requirements. For standard revision increments, say Rev C to Rev D on an established production part, a partial FAI is standard practice.

The real challenge lies in interpreting fit, form, or function. When an engineering team modifies a feature to resolve an assembly clearance issue, fit and form are directly altered. That change requires a delta FAI. If an engineer relaxes a non-critical exterior chamfer from 0.030 inches to 0.045 inches to ease deburring, some teams incorrectly assume the change is cosmetic and skip the FAI update. In aerospace manufacturing, any dimensional modification documented on a released drawing revision affects form. Skipping the delta FAI creates an audit finding during your next AS9100 surveillance audit. When teams fail to align on what constitutes a trigger, communicating design changes to suppliers becomes a primary source of scrap and shipping delays.

Step 3: Scope the Delta FAI: Identifying Which Form 3 Characteristics Need Re-Verification

Scoping a delta FAI requires analyzing both primary and secondary impacts. The primary impact is simple to catch: if an engineer changes a counterbore depth callout from 0.250 inches to 0.275 inches, that specific characteristic requires a new balloon number and re-measurement on Form 3. The secondary impacts are where quality teams get blindsided.

Consider a scenario where an engineer modifies the datum structure in the CAD model to stabilize a machining setup. The physical hole positions might retain their original coordinates relative to the part edges, but their true position tolerances now reference Datum C instead of Datum B. That single datum modification invalidates every positional callout referencing that datum scheme on Form 3. You cannot simply inspect the updated hole. You must re-verify all characteristics tied to that datum reference frame.

Similarly, material removal or wall-thickness changes can alter part stiffness. If an engineer cuts a pocket 2 mm deeper to reduce mass, the revised machining passes may introduce part deflection or thermal warpage during milling. That machining change can push adjacent tight-tolerance bores out of round. A sound delta FAI scope includes: 1) directly revised dimensions, 2) features governed by revised datums, 3) drawing notes added or amended in the revision block, and 4) adjacent features whose manufacturing process was altered by the new toolpath. Document this engineering evaluation before the shop floor cuts metal so your CMM operators know the exact measurement scope required.

Step 4: Document the Rationale: What Your FAI Record Must Show for the Change

When an aerospace auditor or customer quality representative opens your FAI package, they evaluate your delta rationale first. Simply writing "drawing revision" in Field 14 of Form 1 is an immediate non-conformance. Your documentation must present a clear, auditable trail that connects the engineering change to the physical verification.

Field 14 must record three specific elements: the baseline FAI identification number, the specific engineering change order (such as ECO-10492), and a clear statement of why a partial FAI was chosen over a full FAI. A compliant entry reads: "Partial FAI conducted due to drawing revision change from Rev B to Rev C per ECO-10492. Re-inspection restricted to Characteristics 14, 18, and 22 through 26, which were modified by the engineering change. All other manufacturing processes and tooling remain unchanged from Baseline FAI #2024-0412."

On Form 3, best practice is to carry forward the original characteristic numbering while identifying the updated values. If Characteristic 14 was revised, mark it clearly on the delta sheet, reference the new design requirement, and log the actual measurement from the current production lot. Characteristics not affected by the change do not need to be re-measured on the delta sheet, but your summary package must cross-reference the original baseline data. Establishing clear part traceability for hardware manufacturing means serialized components in the field can be traced directly back to either the baseline inspection or the specific delta record that qualified the revision.

Step 5: Link CAD Changes to FAI Scope Before the Question Gets Asked

The root cause of FAI invalidation is the disconnect between design engineering and quality assurance. In traditional hardware workflows, mechanical engineers work inside SolidWorks, Onshape, Fusion, or NX. They modify features, commit changes, update the drawing title block, and release the files through PDM. The quality engineer only discovers the extent of the change days or weeks later, often when a supplier or CMM programmer asks why the CAD model geometry contradicts the baseline inspection plan.

Solving this requires visibility between engineering changes and downstream verification requirements. When an engineering team modifies geometry, the team should immediately know which requirements, interfaces, and inspection characteristics are impacted. Tandem is the context layer for hardware engineering, connecting design intent, requirements, CAD changes, and validation evidence in a single system. Because Tandem integrates off-the-shelf with CAD tools like SolidWorks, Onshape, Fusion, and NX, teams can link CAD modifications directly to requirements and verification checks.

When a designer alters a wall thickness or moves a mounting pattern, the change is not trapped inside the CAD file. The team can identify what the change affects and evaluate requirement checks against the linked CAD geometry. This visibility allows quality and manufacturing engineers to scope the delta FAI at the same time as the engineering change order, rather than reconstructing the rationale after parts are machined. Implementing structured cad revision history best practices keeps engineering decisions linked to physical inspection plans across the entire program lifecycle.

What Triggers the Most Common FAI Disputes: and How to Avoid Them

Disputes over AS9102 validity usually occur at source inspection or receiving inspection when a customer refuses to accept a shipment. The most common dispute involves drawing notes. Mechanical engineers frequently update general notes, such as adding a requirement for ultrasonic cleaning, changing a dry-film lubricant spec, or altering standard edge-break dimensions from 0.005-0.015 inches to 0.002-0.010 inches. Because notes lack physical dimension lines, teams often forget to assign them balloon numbers on Form 3. An auditor will spot the un-ballooned note revision immediately and reject the entire FAI package.

A second common dispute centers on sub-tier supplier processing. If your revision changes the material temper, heat treat duration, or plating thickness, your sub-tier suppliers must also provide updated documentation for Form 2. Presenting an updated Form 3 with new dimensional data while attaching an outdated certificate of conformance (CoC) from your plating vendor on Form 2 will stop an audit cold.

To prevent these disputes, institute a mandatory quality sign-off on every engineering change order before the ECO is released to production. That sign-off must include a completed delta FAI plan that explicitly lists: 1) all affected balloon numbers, 2) all affected drawing notes, 3) any sub-tier processor certifications requiring renewal, and 4) the serialized parts designated for physical first article measurement. When your rationale is documented prior to production, customer source inspectors have no basis for refusal.

Conclusion

An AS9102 first article inspection is only as good as its connection to the current design revision. When CAD models and drawings evolve, treating your FAI as an isolated paperwork exercise guarantees shipping delays, costly re-inspections, and audit findings.

Tandem gives aerospace and defense hardware teams the connected context needed to keep verification in sync with active design changes. By linking CAD models from SolidWorks, Onshape, Fusion, and NX directly to requirements, design decisions, and validation evidence, Tandem makes change impact visible before manufacturing begins. Book a demo with Tandem to see how your team can trace design modifications to verification records and eliminate FAI disputes.