Scott writes:<<<You recently described an "experiment" where you wrapped some tube interconnecting turbo components and later found heat deterioration of the metal. You then conducted another experiment by constructing a replacement part and a shield.  I hope this new experiment achieves the desired result.  Did you log these changes and the fly off tests?  Did you have an FAA inspector approve these experiments?>>>>

To answer your questions, yes I did (and always do) log the repairs and test fly the aircraft after any significant maintenance. The test flight is followed by an inspection.  FAA approval is not required (according to my FSDO) if the form, fit and function of the component is unchanged. When I changed propeller types a few years ago I did inform them.

As soon as I discovered the distorted tube I said to myself: "Self, you don't want to fly with that part on the airplane. I don't think it is airworthy." and promptly set about replacing the part. Had I simply replaced the heat wrap on the distorted part I likely would have needed FAA approval because the component no longer resembled, within reason, the original condition.

If a builder applies some spiral wrap to a hydraulic line and that spiral wrap then breaks and falls off but the original hose remains in near new condition then there is no problem with the hose. If the hose itself starts to crack and fall apart then there is a problem.

The critical question is if the functional capability of the component is compromised. The spiral wrap and the heat wrap are separate parts from the hose or tube and so their performance is independent of the thing they surround.

Regards
Brent Regan