Time Changing Hoses

Christopher Murphy · #1 03-05-2009, 08:19 AM

What has been the normal time change interval for aeroquip 303 hoses? Mine have been on for 8 years and 400 hours but they are in good shape. Should I change them anyway?

What is the guideline for time changing Aeroquip 601/701 steel braided lines like van sells? Do they have the same problem or should a guy just check their condition?

Chris Murphy RV-4

Mel · #2 03-05-2009, 08:26 AM

Typically hoses, except for the Teflon lined, have a 5 year time life. This includes shelf life before installation. Supposedly the Teflon hoses don't have a time life.
Standard hoses will last quite a long time if they are not "moved". Any movement of an old hose tends to start it cracking on the inside.

osxuser · #3 03-05-2009, 08:56 AM

I usually do them at 7 years, regardless of hours. If you have 303, i'd redo them in 303. You can buy the mandrels and the hose, and do them yourself, reusing the fittings on the current hoses... just mark everything well.

az_gila · #4 03-05-2009, 09:41 AM

Quote:

Originally Posted by Mel

Typically hoses, except for the Teflon lined, have a 5 year time life. This includes shelf life before installation. Supposedly the Teflon hoses don't have a time life.
Standard hoses will last quite a long time if they are not "moved". Any movement of an old hose tends to start it cracking on the inside.

...conservatiive than the Mil Specs that our hoses were made to...

It seems that 8 years is a much closer number for rubber hoses, and that does not include some of the storage time (shelf life).

AC 43.13 just tells us to look to the manufacturer's data, so the Mil Spec seems to be the most applicable if we are buying good hoses.

Sacramento Sky Ranch has a good article here...

http://www.sacskyranch.com/h_life.htm

Exact details are in AS 1933 from the SAE, but that spec. costs $$$ - does anyone have access to it?

osxuser · #5 03-05-2009, 10:41 AM

Well, the 5 year number comes from some Cessna and Piper SB's and AD's about hoses used in firewall forward applications. People accept this as manufacturers data.

Mel · #6 03-05-2009, 03:41 PM

I'm not sure where I got the 5 year time. Probably from memory. But then I am somewhat conservative when it comes to advice. When given a spec, so many people, think, "They must have a guard band. What can I really get by with?"

az_gila · #7 03-05-2009, 07:36 PM

Quote:

Originally Posted by osxuser

Well, the 5 year number comes from some Cessna and Piper SB's and AD's about hoses used in firewall forward applications. People accept this as manufacturers data.

...8 years or go to teflon.

http://www.airweb.faa.gov/Regulatory...1?OpenDocument

Is there a later one?

buck · #8 03-10-2009, 02:54 PM

I'm using 303 hose on a IO-320 having experience with teflon I found that with time they get very stiff and take a set. This is what happens to 303 when they age. If you try and flex an aged 303 hose it will crack internally, the teflon won't crack but it won't flex either.
Walt RV-6A
IO-320 CS