The Gentle Plane Affiliation, the UK’s principal consultant physique for amateur-built and classic gentle plane, is to take two security actions regarding the usage of 3D printed elements after a Cozy Mk IV crashed at Gloucestershire Airport earlier this yr.
A 3D printed air induction elbow is believed to have ‘softened and collapsed’ when uncovered to warmth from the engine because the plane took flight. The engine misplaced energy on the plane’s last strategy on the runway, inflicting the plane to collide with the ILS localiser antenna array, a ground-based system that gives horizontal steering to plane approaching to land. Although the plane can carry 4 passengers, the pilot was the one individual on board and suffered solely minor accidents. The plane was destroyed.
The Air Accidents Investigation Department (AAIB) has recommended in its report of the incident that the induction elbow was fabricated from ‘inappropriate materials’. The half was bought at an airshow in america and put in by the plane proprietor whereas modifying the gas system of the plane. Per the AAIB report, the proprietor of the plane understood that the half was printed utilizing CF-ABS filament and exhibited a glass transition temperature of 105°C.
FULL REPORT: AAIB investigation to Cozy Mk IV, G-BYLZ
Because the conventionally manufactured half, which was manufactured by laminating 4 layers of bidirectional glass fibre fabric with epoxy resin, had a glass transition temperature of 84°C after post-curing, the proprietor is alleged to have been glad that the element was match to be used. Nevertheless, AAIB’s report says two samples of the air induction elbow had been subjected to testing utilizing a heat-flux differential scanning calorimeter to find out their glass transition temperature. The measured glass transition temperature was 52.8°C for the primary pattern and 54.0°C for the second pattern. The precise materials composition of the 3D printed elbow was not decided.
Moreover, the AAIB report says {that a} assessment of the design of the laminated induction elbow featured a piece of thin-walled aluminium tube on the inlet finish of the half the place the air filter is hooked up, offering a level of temperature-insensitive structural help. The 3D printed induction elbow didn’t embrace the same part of aluminium tube on the inlet finish. A forward-facing air filter had been clamped onto the ahead finish of the elbow, however that is believed to have indifferent because it was discovered unfastened within the decrease engine cowling.
The AAIB report additionally says {that a} elements checklist equipped to LAA Engineering for the gas system modification didn’t embrace the 3D printed induction elbow, and the organisation was due to this fact not in a position to independently assess its airworthiness.
Transferring ahead, the LAA intends to publish an ‘LAA Alert’ relating to the usage of 3D printed elements. All LAA inspectors will obtain this alert and it’ll even be referenced within the Engine Sort Acceptance Information Sheet (TADS) for all engine varieties, guaranteeing it’s used as a reference every time the Allow to Fly for an LAA plane is revalidated.
