The reason the throttle cable is listed as that, is due to the fact you cannot slip the cable out of its outer to inspect it, (on the mixture and the carb heat you can remove the inner, and inspect the inner cable for wear, so there is no life except at engine change because they are visually inspectable for wear by removing the inner.) the reasoning behind the throttle life is if you are on say finals you pull the throttle shut, the cable snaps at idle and you need power again you are going to crash! hence the life imposed on it........ I think Mcfarlane ones have a longer life BTW
Recommended Service Life
Due to the criticalness of engine
controls and considering their
operating environment, the maximum
recommended in service time for
McFarlane engine controls is equal to
the maximum time between engine
overhauls as recommended by the
engine manufacturer.
see page 7
http://www.mcfarlane-aviation.com/pd...g2010-2011.pdf
So the life IS 1500 hrs, but if you find signs of wear by doing the linear check the life of them is less.
Fuel tank one I tend to do on the annual when I do the guaging check and have the tanks empty. I also check the straps as they can break.
Hope that helps?
carb heat is an engine control as it needs a duplicate when replacing.