A metal additive manufacturing build may appear flawless externally yet still contain internal defects undetectable by visual or dimensional inspection. For aerospace programs, such undetected flaws represent an unacceptable risk. Industrial computed tomography (CT) scanning has emerged as the preferred qualification method for 3D-printed flight components because it enables comprehensive internal inspection without cutting, sectioning, or destroying the part.
This guide outlines the typical qualification process for a 3D-printed aerospace component, beginning with the initial baseline scan and concluding with the documentation reviewed by certifying authorities.
CT reconstruction of a 3D-printed aerospace component revealing internal porosity and lack-of-fusion defects for qualification.
Why Industrial CT Scanning Is Central to Aerospace AM Certification
Additive manufacturing aerospace components are constructed layer by layer, with each layer presenting a potential opportunity for defect formation. Powder bed fusion and directed energy deposition processes are particularly sensitive to variables such as laser power fluctuation, scan strategy, powder condition, and thermal history, unlike traditional machining or casting. Consequently, a part may pass surface and dimensional inspections yet still harbor internal voids that compromise fatigue life. The same reliance on process variables outside the printed geometry is why XRAY-LAB’s work on detecting powder contamination in 3D-printed titanium treats powder history as part of the qualification picture, not just the finished part.
X-ray CT addresses this challenge by reconstructing the complete internal volume of a part in three dimensions. Rather than inferring internal conditions from surface indicators, inspectors can directly examine each internal feature and layer interface at the resolution required by the part’s geometry.
Step 1: Baseline CT for Metal AM Aerospace Components Before Post-Processing
Qualification typically begins with an as-built scan, performed prior to hot isostatic pressing, machining, or coating. This baseline scan documents the raw build’s internal condition, independent of any alterations introduced or concealed by subsequent processing steps. For programs qualifying a new part design or machine parameter set, the as-built dataset serves as the reference standard for all subsequent builds.
Step 2: Porosity Detection in 3D-Printed Titanium Aerospace Parts
Porosity represents the most prevalent internal defect in metal additive manufacturing and manifests in two distinct forms that CT can differentiate: gas porosity, which is typically small and spherical and results from trapped gas in the powder or shielding atmosphere, and process-induced porosity, which is associated with insufficient energy density during fabrication. In titanium aerospace structures, where fatigue performance under cyclic loading is critical for certification, CT enables quantification of pore size, shape, and spatial distribution to assess whether the void population meets approved acceptance criteria or necessitates part rejection. This is a distinct discipline from CT applied to other AM geometries, such as the volumetric approach XRAY-LAB uses for CT scanning of 3D-printed metal parts more broadly, where porosity assessment sits alongside dimensional checks.
Step 3: Lack-of-Fusion Detection With CT in AM Builds
Lack-of-fusion defects are more significant than porosity for structural qualification because they form flat, planar discontinuities between adjacent layers or scan tracks, rather than isolated voids. These defects act as pre-existing cracks under load and are a primary cause of premature fatigue failure in additive manufacturing structures. CT differentiates lack-of-fusion from rounded porosity based on defect morphology, which is important because these defect types are often subject to different acceptance limits within the same qualification plan.
Step 4: Comparing CT Data to Design Intent and Acceptance Criteria
After cataloguing internal defects, the CT dataset is compared to the part’s nominal CAD geometry. This comparison reveals both dimensional deviations, such as wall thickness variations from design intent, and the internal defect population, each measured against acceptance criteria established for the part’s application and load case. Similar dimensional comparison against a CAD reference underpins XRAY-LAB’s inspection of other flight-critical geometries, including the ply-stack analysis described in CT inspection of composite fuselage panels.
Step 5: Building the CT Qualification Record for Flight Certification
The final step compiles CT results into a qualification record: the as-built scan, the defect catalogue with size and location data, the dimensional comparison against CAD, and a disposition against the applicable acceptance criteria. This record supports first-article inspection, ongoing production sampling plans, and the traceability that a certifying authority expects to see tied to a specific build, machine, and powder lot. For programs also qualifying additively manufactured lattice structures, where scan time and analysis complexity increase sharply, the approach used for cutting CT scan times on AM turbine blade lattices is directly relevant to keeping a qualification program on schedule.
XRAY-LAB's Expertise in CT Qualification of 3D-Printed Flight Parts
XRAY-LAB works with aerospace manufacturers throughout the AM qualification cycle, from first-article CT scans on new part designs to ongoing production verification. Recent work on detecting powder contamination in 3D-printed titanium and on composite fuselage panel inspection reflects the same underlying discipline applied here: resolving internal structure at a level fine enough to catch the specific defect modes that matter for flight-critical hardware. For higher-density AM builds where scan throughput becomes a bottleneck, XRAY-LAB’s PolyCT approach to aerospace CT inspection extends the same qualification rigor without slowing production volume.
Frequently Asked Questions
Why is CT scanning required for qualifying 3D-printed aerospace parts?
CT is one of the only nondestructive testing methods able to resolve internal porosity, lack-of-fusion, and geometric deviation throughout the full volume of a build, which is necessary because AM defect modes form inside the part, not on its surface.
What defects in metal AM parts can CT detect that other NDT methods miss?
CT resolves gas porosity, process-induced porosity, and lack-of-fusion discontinuities between layers, along with internal geometric deviation from CAD, none of which surface inspection or basic radiography can reliably separate or size.
How does voxel size relate to acceptance criteria for flight-critical AM parts?
Acceptance criteria typically define a minimum detectable defect size, and voxel size must be set small enough relative to that threshold to reliably resolve defects at or below the critical size for the part’s load case.
Can CT replace destructive sectioning for AM process qualification?
CT significantly reduces reliance on destructive sectioning by verifying internal condition on the actual part rather than a witness coupon, though many qualification plans still retain limited destructive testing to correlate and validate CT findings.
What standards or guidelines reference CT for AM aerospace qualification?
Aerospace AM qualification increasingly draws on SAE/AMS additive manufacturing specifications and agency-specific standards such as NASA’s AM requirements, which define the acceptance criteria that CT data is measured against.
