First Article Inspection: What It Is and When to Require It
- carystraley
- Jun 12
- 11 min read
A rejected production run discovered after thousands of parts have shipped is not a quality problem. It is a process failure that a proper first article inspection would have caught before a single production unit left the floor. FAI is one of the most underused safeguards in precision manufacturing, and the manufacturers who skip it consistently pay for that decision later. Understanding what FAI actually covers, what documentation it produces, and when your program genuinely requires one will save your team time, money, and credibility with your customers.
Table of Contents
Quick Takeaways
Key Insight
Explanation
FAI is not the same as a dimensional report
A first article inspection captures material certifications, process records, and functional test results alongside dimensional data. A simple dimensional report covers only one layer of the full package.
AS9102 and PPAP define different but overlapping requirements
Aerospace programs follow AS9102 Rev C. Automotive programs follow AIAG PPAP Level requirements. Knowing which standard applies before the first cut saves significant rework at submission time.
FAI is required every time a process change is made, not just at new program launch
A material substitution, a new supplier, or a change in machining setup can each trigger a partial or full FAI depending on your customer's quality plan.
CMM programming is the backbone of reliable FAI data
Manual measurement introduces operator variability. A properly programmed CMM produces repeatable, traceable measurements that hold up to customer and third-party audits.
Incomplete FAI packages are the leading cause of PPAP rejection
Missing material certs, unsigned design records, or incomplete control plans are the most common rejection reasons, not dimensional failures.
FAI supports long-term production consistency, not just launch approval
The FAI package becomes the baseline record. When a process drifts or a non-conformance occurs, that original baseline is what your team references to identify what changed.
Skipping FAI on tooling and fixtures creates silent risk
Gauges and fixtures used in production require the same verification rigor. An unverified fixture can systematically bias every part it touches.
What Is First Article Inspection?
First article inspection is a structured, documented verification process applied to the first production-representative part or assembly manufactured from a new or changed process. The goal is to confirm that the part, as actually made with production tooling, production materials, and production settings, meets every requirement on the engineering drawing or specification before full production volume begins.
The key phrase is production-representative. A prototype machined on a different machine, with a different operator, or from a non-production material batch does not qualify as a first article. FAI must reflect the actual production conditions that will generate every subsequent unit.
In practice, FAI serves two simultaneous purposes. First, it gives the customer objective evidence that the supplier understands and can produce to the design intent. Second, it gives the supplier a documented baseline that defines the acceptable process state at the time of launch.
What FAI Covers: The Full Scope of Documentation
Most engineers think of FAI as a balloon drawing with measurements filled in. That is one element. A complete FAI package is considerably broader and, when done correctly, documents the entire chain of evidence from design input to physical output.
Design Record and Drawing Accountability
The FAI must reference a specific, controlled revision of the engineering drawing or model. Every characteristic, every note, and every referenced specification must be accounted for. If the drawing calls out a surface finish standard, that standard must be verified, not assumed. A common mistake is submitting an FAI against an informal or preliminary drawing revision that the customer has already superseded.
Material Certifications
Material certs must match the specific lot or heat of material used to produce the first article. Generic certs or certs from a previous order do not satisfy the requirement. For aerospace and defense applications, the cert must trace directly to a qualified material specification such as AMS or ASTM. SCPM's process requires that material traceability is established before the part is even set up on the machine.
Dimensional Reporting
Every characteristic on the drawing must be measured and reported. This includes basic dimensions, toleranced dimensions, geometric dimensioning and tolerancing (GD&T) callouts, and any notes that imply a measurable requirement. CMM programming at SCPM handles this systematically, eliminating the selective measurement that sometimes occurs with manual inspection.
Functional and Special Characteristics
Special characteristics, those flagged by the customer as critical or significant to fit, form, or function, require additional verification rigor. This may include capability data, functional assembly checks, or specific measurement methods defined by the customer.
Process Documentation
The FAI package typically includes or references the control plan, process flow, PFMEA, and work instructions that govern how the part is made. This is not paperwork for its own sake. It is the mechanism that ties the approved part to a documented, repeatable process.
Pro tip: Build your FAI checklist from the customer's specific quality plan or purchase order requirements before you start any documentation. Retrofitting a generic FAI template to a customer-specific requirement almost always results in gaps that require resubmission.
AS9102 and PPAP: The Two Standards That Define FAI
Two standards dominate FAI requirements in precision manufacturing. Which one applies to your program depends on the industry and the customer, not your preference.
AS9102 Revision C is the aerospace standard for first article inspection. It defines three forms: Form 1 covers design documentation, Form 2 covers product accountability, and Form 3 covers dimensional results. AS9102 is explicit about what constitutes a complete FAI and what events require a partial or full repeat FAI.
"The purpose of the First Article Inspection is to provide objective evidence that all engineering design and specification requirements are properly understood, accounted for, verified, and documented." - SAE International, AS9102 Revision C
PPAP (Production Part Approval Process), governed by the AIAG PPAP manual, is the automotive industry's equivalent framework. PPAP defines five submission levels, from Level 1 (a part submission warrant only) to Level 5 (a full package reviewed at the supplier's facility). Most new automotive programs require Level 3, which includes a full dimensional evaluation, material certifications, initial process studies, and a control plan.
A2LA accreditation, which SCPM holds, matters here because it gives customers independent assurance that the measurement systems and calibration processes behind the FAI data meet internationally recognized standards. An FAI from an accredited lab is not simply a supplier's word. It is documented evidence backed by third-party oversight.
The FAI Machining Process Step by Step
Understanding the sequence of a properly executed FAI in a machining environment removes the ambiguity about what your shop or supplier should actually be doing.
Step 1: Drawing and Specification Review
Before the part is cut, the engineering drawing is reviewed against the applicable specifications. Every callout is identified and assigned a measurement method. GD&T features are assigned to CMM routines. Surface finish callouts are assigned to profilometers. This is not optional pre-work. It is the step that prevents a missed characteristic from invalidating the entire submission.
Step 2: Process Setup to Production Conditions
The machine setup must reflect production conditions. This means production tooling, production programs, and production operators. At SCPM, 5-axis CNC milling and lathe machining setups used for FAI parts are the same setups that will run production. No adjustments are made between the FAI run and production approval.
Step 3: Part Measurement and Data Collection
CMM programming generates the dimensional report. Every characteristic is measured, and the data is recorded against the nominal and tolerance values on the drawing. Statistical data such as Cpk is calculated for critical characteristics when required by the customer's quality plan.
Step 4: Package Assembly and Submission
All elements, dimensional data, material certs, process records, and design documentation, are compiled into the submission package. The package is reviewed for completeness before it leaves the facility. Incomplete packages are the leading cause of FAI rejection, not dimensional failures.
Pro tip: Do not submit an FAI package on a Friday afternoon expecting Monday approval. Build submission lead time into your program schedule. A thorough customer review takes time, and revision requests require additional measurement cycles that can add days to your launch timeline.
When to Require FAI: The Specific Triggers
FAI is not a one-time event at program launch. Several specific conditions require a partial or full FAI repeat, and missing these triggers is where quality escapes tend to originate.
A new part number or a new program always requires a full FAI. There is no ambiguity here. Any part being produced for the first time from a new process requires complete first article documentation.
A design change requires at minimum a partial FAI covering the characteristics affected by the change. If the change affects the manufacturing process, a full FAI is typically required. Never assume a drawing revision only affects one characteristic without verifying the downstream impact on the process.
A process change, including a change in machine, tooling, fixturing, material supplier, or manufacturing location, requires a partial or full FAI. This is where many shops create undocumented risk. Switching from one grade 316 stainless supplier to another is a process change. Moving a part from one machining cell to another is a process change.
A production gap, defined by most quality standards as a period of inactive production, typically 12 or 24 months depending on the customer's quality requirements, requires a repeat FAI before resuming shipments. Tooling wears, setups are lost, and operators change. The repeat FAI confirms the process is still in control.
A corrective action that changes the manufacturing method also requires a new FAI. If a non-conformance root cause led to a change in the control plan or process setup, the corrected process must be formally validated before production resumes.
FAI vs. Incoming Inspection vs. In-Process Inspection
Inspection Type
When It Occurs
Primary Purpose
First Article Inspection (FAI)
Before production release, at process launch or after a defined change event
Validate that the production process can consistently produce parts that meet all engineering requirements
Incoming Inspection
When parts or materials arrive from a supplier
Verify that delivered items conform to purchase order requirements before they enter the production process
In-Process Inspection
During active production at defined control points
Detect and correct process drift before non-conforming parts are completed or shipped
These three inspection types are not interchangeable and they are not redundant. FAI establishes the process baseline. In-process inspection maintains it. Incoming inspection protects the process from non-conforming inputs. Relying on incoming inspection to catch what FAI should have validated is a sign of a broken quality system.
Common FAI Mistakes That Create Downstream Problems
In practice, most FAI failures are procedural, not technical. The measurement equipment is capable. The parts are conforming. The package falls apart because of documentation errors that could have been caught with a thorough internal review.
The most common mistake is submitting an FAI against the wrong drawing revision. This happens when the engineering team updates a drawing after the FAI process has already started. The fix is simple: freeze the design record at the start of the FAI and document the revision level on every page of the package.
The second most common mistake is measuring only the easy characteristics. Manual measurement tends to cluster around the dimensions that are simple to check with a micrometer or caliper. GD&T callouts, true position requirements, and runout tolerances are frequently omitted from manual FAI reports. CMM programming eliminates this bias because the measurement routine is defined programmatically, not by the inspector's judgment in the moment.
A third mistake specific to FAI machining environments is using prototype tooling or setup conditions for the first article part. The part looks correct but the process that produced it is not the production process. The FAI approval then provides false confidence in a process that has never actually been validated.
Missing or mismatched material certifications are the fourth common failure. The cert on file must trace to the specific material lot used for the FAI part. A cert from a previous order, even for the same material grade from the same supplier, does not satisfy the traceability requirement under AS9102 or PPAP.
Inspection Support in Manufacturing: How SCPM Approaches FAI
SCPM's inspection support capability through its MetroLab division is built specifically for the demands that precision machining customers face when meeting FAI requirements. A2LA accreditation means the measurement systems, calibration records, and data outputs used in every FAI package meet internationally recognized standards for measurement traceability.
PPAP documentation is a standard deliverable for production programs at SCPM, not an add-on service. The CMM programming capability allows SCPM to produce fully measured first article reports on complex geometries, including features generated by 5-axis CNC milling that cannot be practically measured with manual gauging.
For customers requiring cleanroom-level handling or calibration support alongside their FAI, SCPM's facility includes cleanroom rental and calibration services that keep the entire validation process under one roof. This matters when your schedule does not allow for parts to travel between facilities for different steps of the inspection process.
Wire EDM components, which often carry extremely tight tolerances and complex profiles, are particularly well-suited to SCPM's CMM-based FAI process. The ability to measure intricate wire EDM geometry accurately and produce a traceable first article report is a direct capability match for customers sourcing those components.
SCPM also supports customers who need inspection support during production, not just at launch. In-process CMM checks, gauge correlation studies, and fixture verification are available as ongoing services that connect directly to the baseline established during FAI.
Frequently Asked Questions
What is the difference between FAI and PPAP?
FAI is the inspection and measurement activity that verifies a part meets its engineering requirements. PPAP is a broader submission framework, primarily used in automotive manufacturing, that includes FAI dimensional data as one element alongside process documentation, control plans, material certifications, and the part submission warrant. In aerospace, AS9102 plays a role similar to what PPAP plays in automotive. Many programs require both dimensional FAI data and a formal PPAP submission package depending on the customer's quality requirements.
How many parts are measured during a first article inspection?
Under AS9102, FAI is typically performed on one production-representative part, though customers may require a sample of parts for statistical purposes on critical characteristics. Under PPAP Level 3, the AIAG manual requires a minimum of 30 pieces or three months of production data for initial process studies on special characteristics. The specific quantity should always be confirmed with the customer before the FAI run begins.
Does FAI need to be repeated if we switch material suppliers?
Yes, in most cases. A change in material supplier is considered a process change under both AS9102 and PPAP requirements because the material properties, traceability chain, and potentially the machining behavior of the material all change. At minimum, a partial FAI covering material-related characteristics and updated material certifications is required. Confirm the scope with your customer's quality engineer before proceeding.
What is a partial FAI and when is it acceptable?
A partial FAI covers only the characteristics and documentation elements affected by a specific change, rather than requiring a complete re-inspection of all features. AS9102 permits partial FAI for defined change conditions such as a drawing revision that affects only a subset of characteristics. The key requirement is that the scope of the partial FAI is formally agreed upon with the customer before submission. Unilaterally deciding a partial FAI is sufficient without customer agreement is a common source of rejection.
Can a machine shop perform its own FAI or does it require an outside lab?
A machine shop can perform its own FAI provided its measurement systems are calibrated, traceable, and capable of measuring all the characteristics on the drawing. A2LA accreditation, which SCPM holds, provides an additional layer of assurance because it means the measurement processes have been independently assessed against international standards. For high-stakes aerospace or defense programs, customers often require accredited lab data. For general industrial and automotive programs, a well-documented internal FAI using calibrated CMM equipment is typically sufficient.
How long does it take to complete an FAI on a precision machined part?
The timeline depends entirely on part complexity, the number of characteristics, the inspection methods required, and the completeness of the supporting documentation going into the process. A straightforward turned component with 20 to 30 characteristics can be measured and documented in one to two days. A complex 5-axis milled component with GD&T requirements, special characteristics, and a full PPAP package can take one to two weeks when you account for CMM program development, measurement, data analysis, and package assembly. Build this time into your program schedule from the start.
Have you worked through an FAI submission that required a partial repeat due to a process change? Share what triggered it and how your team handled the resubmission, it helps other manufacturers recognize the same triggers in their own programs.
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