A homebuilt light aircraft crashed while on approach to Gloucestershire Airport after suffering from engine power loss. According to the Air Accidents Investigation Branch (AAIB) report [PDF, via BBC], the incident occurred when a 3D-printed plastic air induction elbow “softened and collapsed” as the Cozy Mk IV was coming in for a landing. The pilot realized this when he tried to add power while on final, as the engine failed to respond to his input. With the aircraft’s air intake practically blocked, it suffered from a complete loss of power, resulting in the plane landing short of the runway.
“He managed to fly over a road and a line of bushes on the airfield boundary, but landed short and struck the instrument landing system because coming to rest at the side of the structure,” said the AAIB report. The pilot reportedly acquired the 3D-printed part at an air show in the U.S., but it’s unclear whether he acquired it from a licensed dealer.
Nevertheless, the vendor claimed that the part was printed using CF-ABS or carbon fiber-acrylonitrile butadiene styrene filament that can withstand up to 105 degrees Celsius. On the other hand, the plans for the Cozy Mk IV required an air induction elbow with a glass transition temperature of 84 degrees Celsius. Given that the 3D-printed CF-ABS part had a higher temperature ceiling, the pilot was confident that it exceeded the airplane manufacturer’s minimum requirement.
However, one thing he did not consider was that the original plan for the air induction elbow had a section of aluminum tubing near the inlet, which served as a “temperature-insensitive” structural support for the part — something that the 3D-printed part was lacking. Furthermore, the authorities measured the failed part with a heat-flux differential scanning calorimeter and determined that it would’ve failed at temperatures ranging from 52.8 to 54 degrees Celsius — well under the required temperature of the manufacturer.
This incident highlights the importance of following safety protocols in aviation and shows that ignoring one or more regulations can lead to a Swiss Cheese event where different mistakes align to create an accident. The AAIB report says that the pilot applied for a prototype modification of his aircraft to the Light Aircraft Association (LAA) Engineering, and was approved for it, but neglected to mention the addition of this 3D-printed part.
3D printing is widely used in the aviation industry, especially as it allows aircraft manufacturers to quickly produce the necessary parts to keep planes in the air. However, it must follow a strict regulatory process to ensure that these will not fail while in flight, endangering both the aircraft’s occupants and the people on the ground. Thankfully, for this incident, the pilot walked away with just minor injuries, but his aircraft is deemed a complete loss.
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