Sample and inspection planning guide
Enclosure Hardware Samples and First Article Inspection (FAI)
Define what each sample proves, which controlled characteristics must be reported and how production lots will be accepted after first-piece approval.
Direct answer
How Should a Buyer Approve Samples and First Articles?
Treat sample approval, first article inspection and production-lot inspection as separate controls. A prototype confirms only the features it was built to demonstrate. A first article inspection verifies defined characteristics of an identified item against a controlled design record; the first article inspection report (FAIR) documents those results. A lot-sampling plan decides disposition of a production lot and does not guarantee every unit. Identify the deliverable, revision, sample origin, inspected characteristics, measurement rules, report package and events requiring re-inspection.
- Name the exact question, process and approved deviation represented by each sample.
- Connect every reported characteristic to an identified revision, method and sample unit.
- Define production-lot sampling and change-triggered reapproval separately from first article.
TW RFQ combines aerospace FAI, automotive production part approval process (PPAP), dimensional-conformity and acceptance-sampling concepts into a general industrial-hardware purchasing workflow. AS9102 and PPAP apply only when adopted by the relevant contract or customer; this guide does not impose either system on every order.
- AS9102C — Aerospace Series First Article Inspection Requirements — SAE International
- 9102 First Article Inspection Requirement Overview — International Aerospace Quality Group
- PPAP Fourth Edition — Automotive Industry Action Group
- ISO 2859-1:2026 — Sampling Procedures for Inspection by Attributes — International Organization for Standardization
- Acceptance Sampling — National Institute of Standards and Technology
Decision framework
Choose the Approval Record That Matches the Decision
Use only the system required by the buyer or contract. A familiar acronym does not make a report complete or applicable.
| Deliverable | Use and RFQ boundary |
|---|---|
| Appearance or fit sample | Confirms only named visual, tactile, mounting or fit questions. Record every prototype-process deviation. |
| Dimensional sample report | Lists results for agreed characteristics on identified units with characteristic numbers, method, units, tolerances and decision rules. |
| First article inspection report (FAIR) | Documents the results of the required first article inspection against the identified design record and representative configuration. Use a mandated form or submission format only when the buyer or contract requires it. |
| Production part approval process (PPAP) submission | Use only when an automotive customer or program adopts the AIAG process and submission level. |
| Production-lot acceptance sampling | Uses an agreed plan to accept or reject a lot; it does not prove every unit conforms or replace process control. |
| 100% inspection of named characteristics | Define each characteristic, method, record and reaction to nonconformance; “100% inspected” alone is incomplete. |
Name the Question Each Sample Must Answer
A cosmetic mock-up, printed fit check, soft-tool sample, production-tool sample and first production item can represent different materials and processes. State type, quantity, purpose and every deviation from the proposed production route.
Approval should list exactly what was accepted and what remains open. A “golden sample” is useful only when it has an identifier, revision, custody rule and measurable relationship to the controlled record.
Freeze the Configuration Before Measuring It
Identify buyer and supplier part numbers, drawing or model revision, units, BOM revision, material, finish, approved deviations and purchase-order requirement.
Number each reported characteristic so the definition and results have a one-to-one link. AS9102C standardizes aerospace FAI process and documentation requirements and may be contractually required or adopted outside aerospace; it is not automatic for every industrial part.
PPAP is a separate automotive production-approval process. Request its evidence and submission level only when the customer or program adopts the AIAG requirements; do not use “PPAP” as a generic synonym for any sample report.
- AS9102C — Aerospace Series First Article Inspection Requirements — SAE International
- 9102 First Article Inspection Requirement Overview — International Aerospace Quality Group
- PPAP Fourth Edition — Automotive Industry Action Group
Build a Characteristic-Level Inspection Plan
For each characteristic, define limits, sample identity, frequency, method, equipment and result format. Separate variable measurements from attribute checks and identify how visual, functional, material, coating and special-process evidence will be handled.
Avoid “check all dimensions” when reference, basic or process dimensions need different treatment. The buyer must define any defect classification and consequence.
- ASME Y14.5-2018 (R2024) — Dimensioning and Tolerancing — American Society of Mechanical Engineers
Control Traceability and Conformity Decisions
NIST describes metrological traceability as a property of a measurement result connected to a reference through a documented calibration chain, with each link contributing uncertainty. A sticker alone does not establish every later result.
For close tolerances, define how uncertainty affects acceptance. ISO 14253-1 provides conformity decision rules; it does not select the part tolerance or measuring equipment.
- Metrological Traceability — National Institute of Standards and Technology
- ISO 14253-1:2017 — Decision Rules for Verifying Conformity — International Organization for Standardization
Separate First Article from Production-Lot Release
First article evidence addresses the defined initial configuration; production acceptance needs its own plan. ISO 2859-1 provides acceptance quality limit (AQL)-indexed attribute-sampling schemes, while NIST emphasizes that acceptance sampling decides lot disposition rather than estimating every unit’s quality.
Define lot formation, sample selection, inspection level or risk basis, defect classes, rejection response and any screening. State which design, source, process, tooling, site or inspection changes trigger partial or full re-inspection.
- ISO 2859-1:2026 — Sampling Procedures for Inspection by Attributes — International Organization for Standardization
- Acceptance Sampling — National Institute of Standards and Technology
Working checklist
Sample, FAI and Lot-Control Checklist
Record the answer, evidence source and unresolved owner instead of treating a blank field as confirmed.
- Buyer and supplier part numbers, revision and units are recorded.
- Sample purpose, quantity, identifiers and delivery date are stated.
- Production material, tooling, process and location differences are disclosed.
- BOM, material, finish, process and approved-deviation records are identified.
- Ballooned characteristics link each requirement to a reported result.
- Inspection method, equipment and sample-unit mapping are defined.
- Calibration, traceability and uncertainty rules are stated where relevant.
- Functional, visual, coating and destructive-test criteria are explicit.
- The required report package and nonconformance disposition are defined.
- Lot plan, defect classes, reaction and repeat-approval triggers are documented.
Avoidable risk
Approval Records That Prove Less Than They Appear To
Prototype becomes production
A fit mock-up is treated as approval of production material, tooling and process.
Unidentified sample
A result table is not connected to exact units, revision or process origin.
Acronym without scope
FAI, PPAP or AQL is requested without the adopted standard, level, plan or contract requirement.
One approval forever
No material, tool, process, site or source change can trigger reinspection.
Buyer questions
Frequently Asked Questions
These answers are preparation guidance, not a substitute for part-specific engineering or approval.
Does AQL 1.0 mean that 1% defective units are acceptable in every shipment?
No. AQL is an indexing parameter used with a defined sampling scheme; it is not a guarantee that every accepted lot contains no more than that percentage of nonconforming units. State the standard and edition, lot size, inspection level, sampling plan, switching rules and defect classes.
Does approval of one sample approve the complete production lot?
No. It approves only the stated characteristics of the identified sample under agreed conditions. Lot acceptance, process control and change control require separate requirements.
Is AS9102C mandatory for every enclosure-hardware order?
No. AS9102C is an aerospace FAI standard that can be adopted elsewhere. Use it only when the buyer or contract actually requires that reporting system.
What AQL should an enclosure-hardware buyer specify?
There is no universal AQL for every part or characteristic. Select a documented plan from risk, lot size, defect classification, inspection economics and applicable customer requirements.
Is a calibration sticker enough to claim measurements are traceable?
No. NIST states that traceability belongs to the measurement result and requires a documented chain with associated uncertainties. A calibrated instrument is only one input.
Technical reference basis
Primary Sources Used for Scope and Terminology
This guide supports RFQ preparation. It does not replace the cited standards, supplier-controlled drawings, part-specific data, test evidence or responsible engineering approval.
Sources last checked: .
- AS9102C — Aerospace Series First Article Inspection RequirementsSAE International
Official current revision establishing aerospace first article inspection and documentation requirements.
- 9102 First Article Inspection Requirement OverviewInternational Aerospace Quality Group
Official industry overview clarifying the aerospace context and adoption boundary.
- PPAP Fourth EditionAutomotive Industry Action Group
Official automotive production part approval manual page; PPAP is not a generic name for every sample report.
- ISO 2859-1:2026 — Sampling Procedures for Inspection by AttributesInternational Organization for Standardization
Official current edition for AQL-indexed lot-by-lot attribute sampling schemes.
- ISO 14253-1:2017 — Decision Rules for Verifying ConformityInternational Organization for Standardization
Official scope for geometry conformity decisions considering measurement uncertainty.
- Acceptance SamplingNational Institute of Standards and Technology
Official handbook explaining that acceptance sampling primarily supports lot disposition.
- Metrological TraceabilityNational Institute of Standards and Technology
Official explanation that traceability is a property of a measurement result supported by a documented calibration chain.
- ASME Y14.5-2018 (R2024) — Dimensioning and TolerancingAmerican Society of Mechanical Engineers
Official scope for the controlled dimensional and tolerancing record used in characteristic-level inspection.