Crash of a light aircraft highlights risks of unvalidated 3D-printed aircraft parts

3D printing has established itself in the hobby and maker sector as a tool for inexpensive replacement parts, such as furniture fittings, electronics mounts, or components for 3D printers. However, the use of such components in safety-critical systems such as aircraft poses considerable risks. This is demonstrated by an incident in the UK in which a light aircraft crashed after a 3D-printed part failed.

The accident occurred on March 18, 2025, in Staverton. A Cozy Mk IV light aircraft lost power on final approach to Gloucestershire Airport and collided with a landing aid. The pilot was alone on board and suffered only minor injuries. The Air Accidents Investigation Branch (AAIB) attributed the loss of engine power to a 3D-printed air intake manifold component that deformed during flight and restricted the airflow to the engine.

The owner of the aircraft had modified the fuel system and purchased a 3D-printed air intake manifold at an aviation event in the US. The part was supposed to be made of carbon fiber-reinforced ABS filament with a glass transition temperature of 105 degrees Celsius. He considered the component suitable because the aircraft’s construction plans specified other intake manifolds made of glass fiber-reinforced epoxy resin with a lower glass transition temperature. However, these original parts incorporate a thin-walled aluminum tube at the inlet that supports the structure regardless of temperature. This element was missing from the 3D-printed component.

Additional tests on samples of the printed manifold revealed a significantly lower glass transition temperature of no more than 54 degrees Celsius. It remained unclear whether the material used actually met the specification. At the same time, the Light Aircraft Association (LAA) had received a modification request for the aircraft that did not mention the 3D-printed manifold. The LAA was therefore unable to verify the airworthiness of this component, although the rest of the modification was approved.

The AAIB considers the combination of unsuitable material and incomplete modification documentation to be the main cause of the accident. In response, the LAA plans to issue a special warning about the use of 3D-printed components in aircraft modifications. The incident highlights that additive manufacturing in aviation requires strict qualification and quality assurance processes. While certified manufacturers systematically test components, unvalidated DIY modifications to safety-critical systems lead to risks that are difficult to calculate.