From a mechanical engineering standpoint, First Article Inspection (FAI) is a formal, comprehensive verification process to validate that a new or modified manufacturing process produces a part that conforms completely to its engineering design specifications.
The core objective is to catch discrepancies early, before full-scale production begins, preventing costly rework and scrap. It is a critical step in quality assurance, especially for new suppliers, complex components, or after any significant change in the manufacturing process, tooling, or location.
The process is driven by the part’s engineering drawings, 3D CAD models, and the bill of materials (BOM). A mechanical engineer’s role is central to defining these specifications, which include:
Critical Dimensions: All key features, especially those with Geometric Dimensioning and Tolerancing (GD&T) like true position, flatness, or concentricity.
Material Verification: Confirming the raw material grade and physical properties meet the specified requirements.
Surface Finish: Measuring roughness or texture to ensure it falls within the specified range.
Functional Testing: Verifying that the part fits, forms, and functions as intended in its assembly.
The physical first part is meticulously measured using tools like CMMs (Coordinate Measuring Machines), optical comparators, and calipers. All results are documented in a formal FAI report, typically using forms like the AS9102 Form (for aerospace) or similar. This report provides objective evidence that the manufacturing process is capable of producing a compliant part, bridging the gap between design intent and production reality.
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Here is a detailed, step-by-step guide on how to perform a First Article Inspection (FAI).
How to Perform a First Article Inspection (FAI)
A First Article Inspection (FAI) is a formal, comprehensive, and documented verification process that proves your manufacturing process can produce a part that meets all specified engineering design requirements. It’s a “catch-all” quality check for the very first part (or first few parts) from a new production run.
When is an FAI Required?
New Part Production: The very first part from a new tool, machine, or process.
Change in Design: After any engineering change order (ECO).
Change in Manufacturing Process: e.g., moving from machining to casting, or changing a supplier.
Change in Location/Tooling: Moving production to a new facility or using new, significantly modified, or repaired tooling.
Long Production Gaps: After a long period of inactivity (e.g., 2+ years) to ensure process stability.
Customer/Industry Mandate: Common in aerospace (AS9102), automotive (AIAG), and medical industries.
The FAI Process: A Step-by-Step Guide
The most common standard for FAI is the Aerospace Standard AS9102, but the principles apply across industries. The process revolves around completing the three main forms: Form 1, Form 2, and Form 3.
Phase 1: Preparation & Planning
1. Obtain and Review All Documentation (“The Digital Thread”)
Gather the complete, released design data package. This is critical. You cannot inspect what you don’t have.
Engineering Drawing: The primary source for dimensions and notes.
3D CAD Model / Model-Based Definition (MBD): The source of truth if called out on the drawing.
Specifications: Any referenced material, process, or testing specs (e.g., AMS, MIL, internal specs).
Purchase Order (PO): For any special customer requirements.
Bill of Materials (BOM): For raw material and component verification.
2. Create a Ballooned Drawing
“Balloon” the drawing by assigning a unique number (balloon) to every single measurable characteristic (dimension, tolerance, GD&T callout, surface finish, note, etc.).
This creates a direct link between the drawing and the FAI report. This is often done with software, but can be done manually.
Example of a Ballooned Drawing:
(Imagine a simple bracket with holes. Each hole’s diameter, position, the overall lengths, thicknesses, and surface finishes would each have their own numbered circle, or “balloon,” pointing to them.)
3. Select the Part(s) for Inspection
The part(s) must be from a production run using the same materials, tools, processes, and personnel intended for the full production order. It cannot be a hand-made “prototype.”
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Phase 2: Execution – The Inspection & Data Recording
This is where you complete the core FAI forms.
Form 1: Part Number Accountability
This form is the “cover sheet” that ensures traceability.
Part Number & Name: From the drawing.
Serial Number (if applicable): Of the specific part inspected.
Drawing Revision: Must match the part.
Supplier/Customer Information: Who made it, who it’s for.
Signatures: Approval from Quality, Manufacturing, and Engineering.
Form 2: Product Accountability
This form verifies that all raw materials, functional coatings, special processes, and purchased components are correct and have the required certifications.
Raw Material: List the material spec (e.g., AL 6061-T6), heat code/lot number, and attach the Material Certification (C of C).
Special Processes: List processes like heat treating, plating, anodizing, etc. Record the spec (e.g., AMS 2472) and attach the Process Certification (C of C).
Purchased/Standard Parts: List any items like bearings, screws, or seals. Record the part number and attach their C of C.
Form 3: Characteristic Accountability (The Heart of the FAI)
This is the master list where you record the verification of every single requirement from the ballooned drawing.
Ref. No.: The corresponding balloon number from the drawing.
Characteristic / Requirement: The description of what is being measured (e.g., “Hole Diameter,” “Position of 4 Holes,” “Surface Finish 32 Ra”).
Specification / Tolerance: The required value from the drawing (e.g., “⌀6.2 ±0.1”, “⌀0.2 M A B C”, “32 μin”).
Measurement Results / Actual:
Record the actual measured value, not just “PASS/FAIL.” (e.g., “⌀6.22”, “⌀0.15”, “28 μin”).
This data is crucial for process capability analysis.
Tool / Gage ID: The unique identifier of the measurement device used (e.g., “Caliper-123”, “CMM-01”, “Surface Tester-ST45”). This proves the device was calibrated.
Verification Status: A simple “PASS” or “FAIL” column.
Key Inspection Principles for Form 3:
Measure Everything: No characteristic is “too obvious” to skip. This includes part numbers, logos, and deburring notes.
Use the Right Tools: Use measurement equipment with a resolution and accuracy that is at least 10:1 (10 times more precise) than the tolerance you are measuring.
Document Everything: If it’s not written down, it didn’t happen. Be thorough and objective.
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Phase 3: Finalization & Corrective Action
1. Review and Assemble the FAI Report
Compile the completed Form 1, Form 2, and Form 3, along with all supporting documentation:
Ballooned Drawing
Material & Process Certifications
Calibration Certificates for all measurement tools used
Copies of the drawing and specifications
2. Address Any Non-Conformances (FAILs)
If any characteristic fails, the FAI as a whole is not approved.
Root Cause Analysis: Investigate why the failure occurred (e.g., incorrect tooling, programming error, misinterpreted drawing).
Corrective Action: Implement a fix (e.g., adjust the CNC program, rework the tool).
Re-inspection: Produce a new part (or rework the existing one if allowed) and re-inspect the failed characteristics. You may need to re-inspect related features.
Document all corrective actions.
3. Approval and Submission
Once all characteristics pass, the authorized personnel (typically Quality Manager and Program Manager) sign Form 1.
The complete FAI package is then submitted to the customer (if required) and archived internally.
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Best Practices for a Successful FAI
Start Early: Don’t wait until the part is made. Begin the documentation (ballooning, form setup) during the planning phase.
Leverage Software: Use dedicated FAI software. It automates ballooning, form generation, and data management, drastically reducing errors and time.
Involve a Cross-Functional Team: The process should involve Engineering, Manufacturing, and Quality to ensure all perspectives are considered.
Be Meticulous: The goal is not just to “pass,” but to prove with objective evidence that you can consistently make a compliant part. A well-executed FAI is the strongest assurance of quality for both you and your customer.
By following this structured process, an FAI becomes more than a paperwork exercise—it becomes a powerful tool for de-risking production, ensuring quality, and building customer confidence.
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