Guy Prevost
Well Known Member
Like several others, I have struggled with protecting my throttle and mixture cables from heat damage. I built my plane with radiant reflectors on the exhaust pipes, but by the end of my first year of flying my throttle and mixture cables were feeling a bit stiff. Sure enough at my annual inspection, I found that the outer covering of my throttle and mixture cables was melted. I am certainly not the first person to experience this, there are several threads on the subject here at VAF.
Because I have an 8A, my exhast pipes can move a maximum of 3/8" in any direction. Basically, I can't move them. Neither can I move the ends of my throttle and mixture cables.
Like others, I decided that insulation would only make the cables come up to an unacceptable temperature more slowly, but eventually on a long flight they would reach a steady state at a temperature that was too high.
Since my under cowl ambient temperatures are not too high for the cables, it became obvious to me that despite the radiant heat reflectors on my pipes, radiant heat transfer was the culprit. My solution (working quite well so far), was to apply a radiant barrier on the (new) cables as well. During my build I had wrapped my fuel line in reflective ThermoTape where it is within 1 1/2" of an exhaust pipe radiant reflector and have been very impressed with how well it held up.
For my control cables, I am now using 5/8" Thermo Sleeve, safety wired at the steel ferrule of the control cables and wrapped in self-fusing silicone tape at the upper end (as a sealant). Having a reflector on both the radiant heat emitter and receiver, should drastically reduce heat transfer to the cable and solve the problem. So far I have found no degradation in my control cable smoothness and the Thermo Sleeve is holding up famously. Thermo Sleeve and Thermo tape are both rated to 2000 dF and reflect very well. Absolute reflection will of course vary with temperature.
In the photo below, you can see the wrap (1.2 years and 140 hours) around a fuel line as well as the new sleeving on the control cables. Hope this helps someone.
Because I have an 8A, my exhast pipes can move a maximum of 3/8" in any direction. Basically, I can't move them. Neither can I move the ends of my throttle and mixture cables.
Like others, I decided that insulation would only make the cables come up to an unacceptable temperature more slowly, but eventually on a long flight they would reach a steady state at a temperature that was too high.
Since my under cowl ambient temperatures are not too high for the cables, it became obvious to me that despite the radiant heat reflectors on my pipes, radiant heat transfer was the culprit. My solution (working quite well so far), was to apply a radiant barrier on the (new) cables as well. During my build I had wrapped my fuel line in reflective ThermoTape where it is within 1 1/2" of an exhaust pipe radiant reflector and have been very impressed with how well it held up.
For my control cables, I am now using 5/8" Thermo Sleeve, safety wired at the steel ferrule of the control cables and wrapped in self-fusing silicone tape at the upper end (as a sealant). Having a reflector on both the radiant heat emitter and receiver, should drastically reduce heat transfer to the cable and solve the problem. So far I have found no degradation in my control cable smoothness and the Thermo Sleeve is holding up famously. Thermo Sleeve and Thermo tape are both rated to 2000 dF and reflect very well. Absolute reflection will of course vary with temperature.
In the photo below, you can see the wrap (1.2 years and 140 hours) around a fuel line as well as the new sleeving on the control cables. Hope this helps someone.
