Metal additive manufacturing — laser powder bed fusion, directed energy deposition, binder jetting — is transitioning from aerospace R&D programs into production qualification. The technology is in production. The global additive manufacturing market in aerospace was valued at USD 3.1 billion in 2023 and is projected to reach USD 6.5 billion by 2028, according to MarketsandMarkets. The FAA issued a Special Conditions notice in 2023 specifically addressing LPBF titanium structural components for commercial aircraft. The U.S. Air Force has awarded multiple production contracts for AM components. The quality management framework has not kept pace.
AS9100 Rev D and EN 9100:2018 were developed around conventional manufacturing: machining, forming, casting, joining, composite layup. The process control concepts embedded in those standards map cleanly onto processes where the part is built incrementally through identifiable manufacturing steps and is accessible for measurement at multiple stages. Additive manufacturing produces a part in a single continuous process. The „in-process inspection“ is largely replaced by process parameter monitoring. The final part surface conceals the internal build quality. And the relationship between process parameters and mechanical properties is governed by a process specification that may be proprietary to the machine manufacturer, validated for a specific alloy and machine configuration, and not transferable without revalidation.
1. Where AS9100 and EN 9100 Are Insufficient for AM
Feedstock Powder Qualification
Feedstock qualification in laser powder bed fusion is not equivalent to raw material qualification for conventional processes. The requirements are more stringent and the failure modes are different. Particle size distribution affects powder flowability and packing density in the build chamber, which affects local porosity in the finished part. Morphology — the shape regularity of individual powder particles — affects melting behavior and solidification microstructure. Moisture content affects the protective gas atmosphere and can produce oxide inclusions. Satellite formation — small particles attached to larger ones — affects powder flow and can cause local defects.
None of these characteristics is captured by a standard raw material certificate for an alloy specification. SAE International’s AMS7000-series specifications for LPBF processing — including AMS7003 (Ti-6Al-4V) and AMS7004 (Ti-6Al-4V ELI) — address process-specific powder requirements that go significantly beyond alloy composition certification. A material certificate confirming that the powder meets the chemical composition requirements of AMS 4999 does not confirm that the powder is processable in a specific LPBF machine to produce parts with the required mechanical properties.
AS9100 Section 8.4 requires verification that externally provided processes meet requirements. It does not define what the requirements should be for AM feedstock, because those requirements did not exist in standardized form when AS9100 Rev D was written in 2016. Organizations doing this correctly have developed internal specifications that reference AMS7000-series requirements and include powder lot testing protocols beyond what the standard requires.
Build Parameter Validation and Change Control
The approved process in additive manufacturing is the build parameter set: laser power, scan speed, layer thickness, hatch spacing, atmosphere control, pre-heat temperature, and post-processing specifications (HIP, heat treatment, surface finishing). Changes to any of these parameters are effectively a process change requiring revalidation.
In machining, a change from one cutting insert specification to an equivalent is a minor change validatable through dimensional measurement. In LPBF, a change in laser power by 5% can alter porosity content, grain structure, and fatigue properties in ways that are not visible in dimensional inspection and may not appear in standard tensile testing — but will manifest in fatigue life at operational stress levels. ASTM Committee F42 on Additive Manufacturing Technologies has been developing process and material standards specifically to address this challenge, including ASTM F3001 (Ti-6Al-4V LPBF) and the F42 process qualification framework.
The AS9100 Rev D requirement for process change notification exists. The standard does not define the re-qualification evidence required specifically for AM parameter changes, because that evidence requirement is technology-specific in a way that the general language of the standard cannot capture. IA9100 is expected to strengthen digitalization and data integrity requirements — which will push AM suppliers toward more structured build parameter documentation — but AM-specific change control requirements will remain in supplemental specifications for the foreseeable future.
Non-Destructive Evaluation for Internal Build Quality
Conventional NDT methods — ultrasonic inspection, radiographic testing, eddy current — apply to AM parts with significant limitations. The internal geometry of AM parts — complex internal channels, lattice structures, thin walls — creates inspection access challenges that do not exist in solid machined parts. The anisotropic microstructure produced by directional solidification in LPBF creates signal interpretation challenges for ultrasonic inspection that require technique development specific to the material-process-part geometry combination.
X-ray computed tomography is the most capable inspection method for AM parts, capable of characterizing internal porosity, detecting lack-of-fusion defects, and measuring internal feature dimensions inaccessible to conventional probing. The FAA’s guidance on AM part approval under the Part 21 type certification framework specifically references CT as a validation tool for internal geometry conformance. However, CT inspection is time and cost intensive, and it is not established as a standard production inspection method in most aerospace supply chains. The accept/reject criteria for defect types and sizes, and the relationship between inspection findings and fatigue life, require engineering judgment and material characterization data that most AM suppliers in the mid-market do not yet have at the depth required for flight-critical component production.
2. What the Industry Is Doing to Address the Gap
Three parallel standardization tracks are active:
SAE International has published the AMS7000-series for LPBF processing of specific alloys, providing process-specific material specifications that go beyond alloy composition. ASTM Committee F42 has published more than 40 standards addressing AM materials, processes, and testing, with the F3001 family covering titanium LPBF specifically. The FAA has published guidance material (Issue Paper and Special Conditions) for AM part approval under Part 21 type certification, establishing a regulatory pathway that did not exist five years ago.
These documents are necessary and valuable. They are also newer than the qualification programmes of the AM suppliers currently working in aerospace production, and they do not yet represent a complete, harmonized framework that an AS9100 auditor can audit against with the rigor applicable to conventional manufacturing processes.
3 Concrete Actions
1. If you are qualifying an AM supplier for aerospace production parts: develop an additive manufacturing quality requirements supplement to your standard supplier quality requirements. The supplement must specifically address: feedstock powder qualification requirements referenced to AMS7000-series or equivalent (not just alloy specification compliance), build parameter documentation and change control requirements with re-qualification trigger criteria, post-process traceability (HIP cycle, heat treatment, surface finishing documentation linked to specific build serial numbers), and inspection method requirements with specific accept/reject criteria for defect types. Do not rely on your standard supplier quality agreement — it was not written for AM.
2. For AM suppliers seeking aerospace qualification: invest in developing your own internal AM process specifications before your first qualification audit. The aerospace customer will ask to see your feedstock specification, your build parameter control procedure, and your change management process for parameter modifications. If those documents do not exist, the qualification audit will identify their absence as a major finding. If they exist but reference only the machine manufacturer’s general operating guidelines without process-specific validation data, they will be assessed as inadequate for production qualification of safety-critical parts.
3. For quality managers with existing AM suppliers: verify whether your current supplier qualification was conducted under AM-specific requirements or under your standard supplier quality process. Most early AM qualifications in aerospace were conducted under standard processes because the AM-specific requirements — SAE AMS7000 series, ASTM F42 process standards, FAA AM guidance — had not yet been developed or were not incorporated into supplier qualification criteria. A qualification audit that did not examine feedstock qualification depth, build parameter change control, and AM-specific NDE methodology is incomplete by current standards and warrants a targeted re-audit of those specific areas.
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Sources
- MarketsandMarkets — Additive Manufacturing in Aerospace and Defense Market: USD 3.1B (2023) to USD 6.5B (2028)
- SAE International — AMS7003: Titanium Alloy Powder, Ti-6Al-4V, for Additive Manufacturing
- SAE International — AMS7000 Series: Laser Powder Bed Fusion Process Specifications
- ASTM International — F3001: Standard Specification for Additive Manufacturing Titanium-6 Aluminum-4 Vanadium (Ti-6Al-4V) with Powder Bed Fusion
- ASTM Committee F42 — Standard Specifications and Practices for Additive Manufacturing, astm.org
- FAA — Special Conditions: Laser Powder Bed Fusion Titanium Structural Components (2023)
- FAA Advisory Circular on Additive Manufacturing Part Approval under Part 21 Type Certification
- AS9100 Rev D / EN 9100:2018 — Section 8.4: Control of Externally Provided Processes and Section 8.5: Production and Service Provision
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