The aircraft owner who installed the modified fuel system stated that the 3D-printed induction
elbow was purchased in the USA at an airshow, and he understood from the vendor that it
was printed from CF-ABS (carbon fibre – acrylonitrile butadiene styrene) filament material,
with a glass transition temperature3
of 105°C.
An alternative construction method for the air induction elbow, shown in the Cozy Mk IV
plans, is a lamination of four layers of bi-directional glassfibre cloth with epoxy resin. The
epoxy resin specified for the laminate has a glass transition temperature of 84°C, after the
finished part has been post-cured. The aircraft owner stated that as the glass transition
temperature listed for the CF-ABS material was higher than the epoxy resin, he was satisfied
the component was fit for use in this application when it was installed.
A review of the design of the laminated induction elbow in the Cozy Mk IV plans showed
that it featured a section of thin-walled aluminium tube at the inlet end of the elbow, where
the air filter is attached. The aluminium tube provides a degree of temperature-insensitive
structural support for the inlet end of the elbow. The 3D-printed induction elbow on G-BYLZ
did not include a similar section of aluminium tube at the inlet end.