Andy, depends on what you have for hoses. All the Mil H8794 hoses, like Aeroquip 303, or Stratoflex 111 should be inspected at each conditional, and replaced at the 8 year mark MAX. Yep, they may look good and clean with no drips, but I'll bet if you removed them and tried to do a flex test, it would sound like Rice Krispies--snap, crackle and--oh boy.
Sam, stainless braided hose is in 2 forms===rubber/neoprene liner, and teflon.
Most of what we are talking about for the 8 year replacement/refirbishment was 303/111 hose--rubber/neoprene liner, nylon reinforcement braid, STEEL reinforcement braid (nope not stainless) then the cotton, supposedly oil resistant cover. Well the cotton absorbs moisture, fluids etc, and causes the STEEL braid to rust and after many cycles gives you the Rice Krispies sound.
Stainless braid, on the other hand, doesnt rust so it maintains (supposedly) its flexibility. But then the rubber liners can deteriorate from fuel additives, oil temps, many cycles, and begin to crack ( or as my Radiology friends say "fracture").
Weve seen them just fine in the plane and working over many years. They take a set and seem fine. But take them out , move them around then do a leak/pressure test on them, and see what happens. MIGHT surprise you.
Teflon hose seems to resist all of these bad things, mainly due to the higher fluid temperature rating of the liner vs rubber liners.
Tom
Tom, I'm not suggesting anyone delay replacing hoses. However, the stainless braided hose with rubber lining that I've used in the RV-6 since 1999 have never shown any form of failure or lack of flexibility each time I have rebuilt them. This gives me confidence the hoses are reliable for my service intervals.
Just another data point.
everyone's worst nightmare!I had just had my annual condition inspection done by an A&P. He said the fuel hoses still felt good (steel braided rubber) -- flexible.
Turning on fuel pump for the next flight I smelled gas.
I took off the cowling, turned on fuel pump and saw gas spewing out through the steel braid!
Granted it's high pressure (40 PSI) and I run mogas.
Now I'm using non-steelbraided hoses and replace them every 3 years.
Finn
Sam, are using mogas?
Tom