Hey Lynn and the rest of you smart guys, What is your opinion on scheduled hose replacement?  My plane has been flying for 6 years now and I just finished the annual.  I decided that 6 years was long enough on some of my radiator hose and decided to replace it.  In particular, I ordered up the AN-16 steel braided hose (Earls Perform-o-flex)  for my coolant out line but I just couldn't bear the thought of cutting and fitting that stuff and hoping I don't get leaks or damage the AN hose fittings or cut my fingers to shreds.  So I decided the current hoses were good for another year.  Maybe a justification...

Opinions on scheduled replacement of SS hose?

--
David Leonard

 

While the stainless braid does degrade over the years, it is usually a mechanical function at Adel clamps and at any location where it touches any other surface. The fine braid wire looks like a knife edge to other material. ( a unit pressure problem). So as long as the rules for braided coverings are observed, it is only the liner to consider.

 

Teflon is great. Light weight, thin, slick flowing, and almost no resistance to being punctured even by its own braid. Neoprene is probably most widely used, and is heavier than Teflon but the added thickness gives a bit more puncture protection, so more time to find a problem on preflight. The quality of this material used in street car hose would be more suspect than say a surplus piece from Boeing, or from an actual hose supplier providing hose to Boeing.

 

Other materials are available now, but even Neoprene should last 10 years.

 

 If you must have a stainless braid,

Wrap the cut area with electrical tape pulled tight. Cut the hose in one motion with an abrasive saw. If you have some shop air blowing through the hose during the cut, any bits of stainless will clear the hose end. Pull the remaining tape off along the hose body not at 90 degrees, so as not to fluff the braid. Clean off any long strands with nippers. Dab on wheel bearing grease right at the end of the braid. Screw on the wrenching sleeve.

 

With a ball stone in a die grinder, radius the liner opening so that the inner fitting does not cut a flapper out of the liner. Use lots of grease. Wear leather gloves and eye protection. Line the vice jaws with Duct Tape. Wrap the anodized surfaces with masking tape. Once you start screwing the inner into the hose don't stop. If you have to stop, back it out and add more grease. Start again. Grease all threads.

 

Perfect hose assemblies in a few minutes. Or have the local hose shop do it. Perfect hose assemblies in a few minutes. 

 

Or, consider silicone hose (no braid) that would outlast the airplane.

 

Lynn E. Hanover