Updated September 18, 2026: Includes the LAA guidance published in July 2026. Originally published December 5, 2025.
A printed aircraft part needs evidence that it is suitable for its intended use. The Cozy Mk IV accident illustrates the consequences of relying on a material claim without establishing the performance of the actual component.
What the AAIB established
On March 18, 2025, G-BYLZ lost engine power approaching Gloucestershire Airport. A printed plastic induction elbow had softened and collapsed, restricting airflow. The pilot sustained minor injuries; the aircraft was destroyed. The modified fuel system had accumulated 37 service hours.
The AAIB investigation, published December 4, 2025, records the owner’s understanding that the vendor supplied CF-ABS with a glass transition temperature of 105°C. Investigators did not determine the actual material composition. Two tested samples measured 52.8°C and 54.0°C. The report does not identify the printer used.
A component omitted from the review
The LAA had approved the fuel-system modification, but the submitted parts list omitted the elbow. Its airworthiness was therefore not assessed. The printed elbow also lacked the aluminum inlet reinforcement shown in the alternative laminated design. The AAIB concluded that its material was unsuitable for the engine-bay temperature.
The report did not establish that this was a consumer-printer failure. Our earlier wording overstated what was known about the material and equipment. The distinction matters when deciding what evidence a replacement part needs.
New LAA guidance: July 2026
On July 2, 2026, the LAA announced Technical Leaflet 3.30 on additively manufactured parts. Its announcement draws attention to material composition, manufacturing process, process settings and build orientation. A material name alone does not establish the properties of the finished print. Significant modifications involving printed parts should be declared to LAA Engineering for assessment.
This is a published development since our original article, not proof that every safety action proposed in the AAIB report has been completed. Consult the LAA’s current leaflet and the approval requirements that apply to the aircraft before making a substitution.
Questions to resolve before ordering a printed part
Start with the component’s function and operating conditions. Give the responsible engineer and manufacturer the drawing, loads, temperature exposure, fluids, interfaces and inspection requirements. Identify which requirements need supporting test evidence and who will approve the finished component for use.
- What evidence applies to the finished part, rather than only the raw material?
- Which build settings, orientation and finishing steps need to be controlled?
- How will the specified dimensions and required properties be verified?
- What records and approvals are required before installation?
These questions help define a manufacturing brief; they are not an airworthiness approval checklist. Buying an industrial print or a material certificate does not by itself authorize installation in an aircraft.
Discussing an aerospace project with Forge Labs
For aerospace manufacturing enquiries, share the part’s intended use, drawings, material requirements and required documentation. Confirm the manufacturing and inspection scope with our team before ordering. Our quality information is a starting point for that conversation; project-specific requirements need to be agreed explicitly.
