3. Pre-assembly inspection

Before a single bolt is torqued on a WorldSID assembly, the build must be proven correct on paper and on the bench. Pre-assembly inspection is the gate where received hardware, part numbers, revision levels, and documentation are reconciled against the build sheet. A WorldSID is a calibrated anthropomorphic test device (ATD), not a generic mechanical assembly: a wrong revision of a rib module, a mismatched lumbar load cell, or a superseded calibration certificate can silently invalidate every subsequent test. The purpose of this inspection is therefore not merely to confirm that "parts arrived," but to establish traceable evidence that the specific serialized components in the crate are the ones the build sheet calls for, at the correct revision, with valid documentation.

What the Build Sheet Actually Specifies

The WorldSID build sheet is the controlling document for the assembly. For each position in the dummy — head, neck, upper and lower torso, ribs, abdomen, pelvis, arms, legs — it lists the required part number, the minimum acceptable revision level, the quantity, and where applicable the serial number of the instrumented component. It also references the instrumentation channel map (load cell and accelerometer IDs, bridge types, sensitivities) and the calibration due dates. Treat the build sheet as the single source of truth: if a component in the crate does not match the sheet, the component is wrong, not the sheet.

A practical inspection works from a printed or controlled digital copy of the build sheet, annotated line by line. The inspector records, for each line item, the observed part number, observed revision, quantity counted, serial number where serialized, and the documentation status. Anything that cannot be positively confirmed is flagged as a hold, not passed by default.

Part Number and Revision Verification

Part numbers on WorldSID components are frequently laser-etched or printed on labels that are small, curved, and sometimes partially obscured by protective caps or cable bundles. Verify the number at the component itself, not from the shipping carton label alone — cartons are reused and mislabeled. Read the full number including any dash suffix, because suffixes often encode handedness (left/right), size, or instrumentation variant. A left and right rib module can share a base number and differ only in the suffix; installing the wrong side is a common and costly error.

Revision level is the second check and the one most often skipped. A component may carry the correct part number but an earlier revision that lacks a required feature, uses a different connector, or has a known defect corrected in a later revision. Compare the observed revision against the minimum acceptable revision on the build sheet using a simple rule: the observed revision must be equal to or later than the specified minimum, and must not be a revision the build sheet explicitly prohibits. Where a revision change alters mass or geometry, the build sheet should state whether the later revision is acceptable for this build; if it does not, escalate rather than assume.

Record revisions exactly as marked, including letter suffixes and date codes. "Rev C" and "Rev C1" are different configurations; transcribing one as the other destroys traceability.

Documentation Checks

Documentation travels with the hardware and must be verified with the same rigor. For each instrumented component, confirm that a calibration certificate is present, that the certificate serial number matches the component serial number, that the calibration is within its stated validity period relative to the planned test date, and that the stated sensitivity and bridge configuration match the channel map on the build sheet. A certificate for the right model but the wrong serial number is not acceptable evidence.

Also confirm that the correct assembly drawing revision and any build-specific work instructions are available at the bench, and that the certificate of conformance or incoming inspection record for the shipment is on file. Missing or mismatched documentation is a hold condition even when the hardware looks correct, because the assembly cannot be released for testing without traceable calibration.

Worked Inspection Example

Consider a build sheet line for the abdomen: part number WSD-AB-2040, minimum revision D, quantity 1, serialized, calibration sensitivity 2.001 mV/V at the stated load. The inspector finds a component marked WSD-AB-2040, revision C, serial AB-1187, with a certificate for serial AB-1187 showing sensitivity 1.998 mV/V and a calibration date eight months before the planned test. The part number matches and the certificate matches the serial, but the revision is below the minimum and the sensitivity differs from the build sheet value. This line is a hold: the revision is not acceptable, and the sensitivity discrepancy must be resolved against the channel map before the component is used. The inspector documents the observed values, marks the line "HOLD — revision below minimum; sensitivity mismatch," and quarantines the component.

By contrast, a line for a non-instrumented pelvic spacer with part number WSD-PS-1102, revision B, quantity 2, no serial, no calibration requirement, passes when two components are counted and both are marked revision B or later with no prohibited revision present.

Disposition and Release

Every line ends in one of three dispositions: accept (all attributes match), hold (a discrepancy exists that may be resolvable by substitution, rework, or engineering disposition), or reject (wrong part, damaged, or documentation invalid and not recoverable). Holds and rejects are physically segregated and labeled so they cannot be picked during assembly. The build is released to assembly only when every line is accepted or a documented engineering disposition covers the exception. The completed inspection record — annotated build sheet, certificate copies, and disposition log — becomes part of the device's build history and is retained for the life of the assembly.

WorldSID pre-assembly inspection flow: build sheet line items reconciled against received components and documentation A diagram showing the build sheet as the controlling input, three parallel verification checks (part number, revision level, documentation), and a disposition decision producing accept, hold, or reject outcomes, with a release gate to assembly. WorldSID Build Sheet part no. · min revision qty · serial · channel map Received Components crate contents, labels, certificates, drawings Check 1 — Part Number full number incl. dash suffix read at component, not carton Check 2 — Revision Level observed ≥ minimum on sheet no prohibited revision present Check 3 — Documentation cert serial = component serial cal valid · sensitivity matches Disposition per Line all attributes match? accept → release to assembly hold → segregate, resolve reject → quarantine, replace Release Gate every line accepted or covered by engineering disposition Inspection record retained in build history: annotated build sheet · certificate copies · serial numbers · disposition log · inspector sign-off

Common Failure Modes and How to Catch Them

Three failure patterns account for most pre-assembly escapes. First, carton-label trust: the inspector records the part number from the shipping label without opening the packaging, and a reused carton conceals a wrong component. Catch it by verifying at the component. Second, revision blindness: the part number matches, so the line is passed without reading the revision suffix. Catch it by making revision a mandatory field on every line, not an optional note. Third, certificate mismatch: a valid certificate is present but belongs to a different serial number or a different sensitivity. Catch it by cross-checking serial and sensitivity against the channel map, not just confirming that a certificate exists.

When a discrepancy is found, do not attempt to "make it fit." Record the observed value, the required value, and the difference; segregate the component; and route the line to engineering disposition. A documented hold that is later resolved is a controlled event. An undocumented substitution is an uncontrolled one that may not surface until the device fails a calibration check or produces anomalous test data.

The output of this stage is a fully annotated build sheet in which every line carries an observed part number, revision, quantity, serial (where applicable), documentation status, and disposition, backed by retained certificate copies. That record is what allows the assembly to proceed with confidence and what allows any later anomaly to be traced back to a specific component and its calibration history.

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