Current-syllabus supplement; see the primary references below.
Layer-based manufacture
Additive manufacturing builds geometry by adding material according to a digital description, often in successive layers. It differs from machining that removes stock and from casting into a mould. Complex internal passages and reduced assembly count can be useful, but shape alone does not establish equivalent performance. The build process can influence material properties and surface condition. An aircraft application therefore depends on controlled design, material, manufacture, inspection and eligibility, not simply on whether a printer can reproduce the visible outline.
What distinguishes additive manufacture? Material is added to form the intended geometry.
Common process families
Powder-bed fusion uses energy to fuse selected areas in a powder layer. Directed-energy deposition feeds material into a focused energy region as deposition occurs. Material extrusion places material through a nozzle, while vat photopolymerisation cures a light-sensitive liquid. Binder jetting uses a binder to join powder and may need subsequent processing. Process names describe different mechanisms; a polymer extrusion machine and a metal powder-bed machine do not produce interchangeable outputs. Identify the specified process before discussing the finished part.
Which process fuses selected regions of a powder layer? Powder-bed fusion.
Build direction and support
A digital model must be prepared for the chosen process, including orientation, layer strategy and required supports. Build direction can affect surface finish, dimensional accuracy and directional properties. Overhangs and internal features can need support or special process planning. Support removal itself can damage a part if uncontrolled. A changed orientation or parameter set may fall outside a qualified production process even when the model is unchanged. Dimensional agreement is one part of conformity, not the whole assessment.
Why does build orientation matter? It can affect properties, finish and support requirements.
Process and material control
Material identity and lot traceability link a finished part with its production history. Equipment condition and the specified build parameters must be controlled. Powder handling requires precautions appropriate to its fire, inhalation and contamination hazards; different materials require different controls. A production record can include the machine, feedstock, build file, parameters and subsequent processing. Do not treat an unrecorded reprint as automatically equivalent to an approved part. Controlled repeatability matters as much as a successful first demonstration.
What supports production traceability? Records linking material, process and finished part.
Post-processing and inspection
A printed part may require cleaning, support removal, heat treatment, machining or other specified finishing. Inspection methods must address the manufacturing defect limits and the application's acceptance requirements. Potential problems include porosity, inadequate fusion, distortion and surface defects. The manufacturer defines the qualified inspection and test plan; looking at the surface alone may miss internal features. Changes to post-processing can change the final properties, so they form part of the controlled route rather than an optional cosmetic step.
Why can a printed part need internal inspection? Manufacturing defects may exist below the visible surface.
Maintenance relevance and eligibility
A maintenance technician may encounter approved additive-manufactured components or tools. Confirm identity, installation eligibility and the applicable maintenance instructions through the normal controlled process. The ability to print a replacement does not authorise installing it on an aircraft. Approved production, design and installation requirements still apply. Repair or modification of a printed component must use applicable data; do not assume that a repair qualified for conventionally manufactured material applies unchanged. Treat additive manufacture as a production method, not an exemption from airworthiness controls.
Does the ability to print a matching shape establish installation eligibility? No; the applicable approval and eligibility requirements still apply.
Apply the knowledge
Work through these examples before starting the quiz. Explain why the other choices would not meet the requirement.
A printed bracket has the same dimensions but no acceptable traceability. What is correct?
Resolve eligibility through the approved process before installation — Geometry does not replace controlled identity and eligibility.
A production build orientation changes. Why might this need assessment?
It can change process-dependent properties and conformity — Orientation is part of the controlled manufacturing route.
Porosity is suspected in a metal printed part. What is appropriate?
Use the specified inspection and acceptance process — Internal quality cannot be established from appearance alone.
A printed part needs specified heat treatment. Can it be omitted if dimensions are correct?
No; the complete qualified process must be followed — Material properties and conformity depend on the complete manufacturing route.