Ask the A&Ps 5-year Rubber Replacement

[Bulldog]

Mike Busch’s take on the 5-year rubber replacement in the latest episode of the Ask the A&Ps podcast:

https://podcasts.apple.com/us/podcast/ask-the-a-ps/id1527442466?i=1000638694295
 

The discussion starts at about minute 23.

[Bill3558]

VERY interesting.  “I wouldn’t hesitate to go 10 years”.  Pretty ballsy statement.

Now that I am experimental I feel better about using “on condition” and common sense to keep the plane safe to operate.  I will push the chute repack as well. 

 

[Anticept]

The 5 year is an ultra conservative number. For some of the ADs out there on some hoses for other aircraft types, replacement times are 7-10 years.

It also depends on the quality of hose.

There's too many variables to accurately say what should be recommended, but universally, we know at some point these rubber hoses dry rot, crack, leak, etc. It's no surprise Rotax chooses 5 years because that protects them from tort. It's a decent practice but I also agree that 5 years is a tad on the conservative side.

[Jim Meade]

3 hours ago, Bill3558 said:

VERY interesting.  “I wouldn’t hesitate to go 10 years”.  Pretty ballsy statement.

Not very risky.  One is inspecting on condition as one goes, so if a hose goes bad one is likely to catch it.  Some certificated airplanes go well over 10 years based on "on-condition" inspections.  One could as Corey says conclude that a 5 year hose change is ultra conservative.  It's known that maintenance induces errors, so changing hoses before they need to may be more risky than expecting a 10 year change interval.

 

 

[airhound]

Nice nails sailor! Say was the Kitfox accident due to hose wear…err?

[Jim Meade]

Neither of the instances you cite have to do with defective hoses.  They are not germane to the discussion of hose replacement criteria, they just confuse the issue.

[Madhatter]

Roger and I don't always agree on everything, but on this I am 100% with him. Rubber change is the cheapest insurance for a 912. 

[FredG]

I like to change my hoses at every annual.  Can't be too careful and I appreciate all the experts who have made that clear.

[Madhatter]

45 minutes ago, FredG said:

I like to change my hoses at every annual.  Can't be too careful and I appreciate all the experts who have made that clear.

Definitely overkill

[FlyingMonkey]

On 12/16/2023 at 4:50 PM, Bill3558 said:

VERY interesting.  “I wouldn’t hesitate to go 10 years”.  Pretty ballsy statement.

Now that I am experimental I feel better about using “on condition” and common sense to keep the plane safe to operate.  I will push the chute repack as well. 

 

I went six years last time, and then replaced all fuel and oil hoses with very high quality teflon/stainless lines.  So now I don’t really need to worry about them for a LONG while.  I replaced all the lower coolant hoses with silicone hoses.  I left the rubber hoses alone off the coolant spider tank, as they all looked great.  When they start looking aged they’ll get swapped out with silicone too.

[FlyingMonkey]

2 hours ago, FredG said:

I like to change my hoses at every annual.  Can't be too careful and I appreciate all the experts who have made that clear.

You spend $1000+ every annual for hoses?  That is over the top, IMO.

[FredG]

Good grief.  No, I do not change hoses every annual.  I was trying to comment on the fear mongering warning me that I am going to crash and burn because I might be skeptical about the Rotax 5-year requirement.  After all, if the goal is to be safe, why not be really, really, safe.

After all, can we be really, perfectly, totally, absolutely certain that no hose will ever need to be replaced before five years?  At some point, the argument about the frequency of hose changes amounts to religion (or, possibly, self-interest if one is in the business of hose replacement) and not to actual risk assessment.  If risk assessment was the issue, I would expect Hobbs time to be the better indicator of hose life and not calendar time, anyhow.  

BTW, except for coolant hoses, all hoses on my E-LSA airplane are custom stainless braid/teflon with a lifespan that exceeds my natural life expectancy.  I will switch lower coolant hoses to silicone at the next 5 year change.  It may be hard to find silicone hoses for the top of the engine due to the bends required.

[FlyingMonkey]

1 hour ago, FredG said:

Good grief.  No, I do not change hoses every annual.  I was trying to comment on the fear mongering warning me that I am going to crash and burn because I might be skeptical about the Rotax 5-year requirement.  After all, if the goal is to be safe, why not be really, really, safe.

After all, can we be really, perfectly, totally, absolutely certain that no hose will ever need to be replaced before five years?  At some point, the argument about the frequency of hose changes amounts to religion (or, possibly, self-interest if one is in the business of hose replacement) and not to actual risk assessment.  If risk assessment was the issue, I would expect Hobbs time to be the better indicator of hose life and not calendar time, anyhow.  

BTW, except for coolant hoses, all hoses on my E-LSA airplane are custom stainless braid/teflon with a lifespan that exceeds my natural life expectancy.  I will switch lower coolant hoses to silicone at the next 5 year change.  It may be hard to find silicone hoses for the top of the engine due to the bends required.

Haha, gotcha.  I clearly misunderstood.  I agree with you!

[GlennM]

19 hours ago, Jim Meade said:

Neither of the instances you cite have to do with defective hoses.  They are not germane to the discussion of hose replacement criteria, they just confuse the issue.

Those damn germanes, they cause all the trouble. 

[Bill3558]

I admire you guys that have the skills to do it your self. I don’t.  

It’s not a question of money. My problem is finding a competent mechanic that is familiar with Rotax rubber changes. My local A&P is not keen on doing it. 

I’m in Hendersonville NC. Any suggestions appreciated. 

 

[Jim Meade]

You obviously didn't listen to the podcast very closely.  Your conclusions are unwarranted and inaccurate.

[Madhatter]

12 hours ago, Bill3558 said:

I admire you guys that have the skills to do it your self. I don’t.  

It’s not a question of money. My problem is finding a competent mechanic that is familiar with Rotax rubber changes. My local A&P is not keen on doing it. 

I’m in Hendersonville NC. Any suggestions appreciated. 

 

It's pretty sad that an A&P is hesitant to change rubber hoses. I've been involved in aircraft maintenance for 51 years now and have seen the mechanic competency decline considerably,  as has the airlines and other aviation businesses. The good , competent A&P's are working for large companies paying high wages and benefits. What is left is what you see running around telling you how great they are but can't seem to get the job done, I see this everyday. And if you think good A&P's are hard to find,  try finding avionics people. 

[FlyingMonkey]

13 hours ago, Bill3558 said:

I admire you guys that have the skills to do it your self. I don’t.  

It’s not a question of money. My problem is finding a competent mechanic that is familiar with Rotax rubber changes. My local A&P is not keen on doing it. 

I’m in Hendersonville NC. Any suggestions appreciated. 

 

I understand if you don't want to do it (it's a bit of a PITA), but if you can turn a wrench you can do a hose change.  You're not that far from me.  If your airplane is ELSA and you decide you want to try to tackle it, send me a PM.  I can fly up and talk you through it and assist.

[Tom Baker]

First off let me say everyone makes mistakes whether it is offering advise or doing work. I know I have made mistakes. In my opinion the advice being offered in this VLOG is a mistake.

In my observations of doing maintenance on CT's the past 15 years I would say that it is likely that going past 5 years will not be a safety issue, but it is hard to tell when it will be an issue. Unless you can verify the material choices made by the installer, and are comfortable with the quality of work I would say the 5 year replacement is a good thing.

I have found issues with oil hoses from both substitution of non Rotax hose and safety related installation errors. The installation errors were from the factory and well respected LSA mechanics. The installation error is poor positioning of the Band-it clamp for the fire sleeve causing a constriction of the oil hose. I have posted pictures before.

I have seen problems with fuel hoses. Mostly from the wrong sizes being used causing leaks, but also some poor quality hoses. I had one customer have a forced landing due to a bad fuel hose replaced during a hose change the year before I started working on the airplane. It came apart on the inside and a little peice of rubber blocked off the fuel inlet on the 2-4 carburetor. When you shut down one side of the engine it is not good. I had one batch of hose that I bought that I sent back to the supplier because I didn't like the quality, and it did meet the required DIN specification. The hose would collapse and kink when bent around a reasonable radius. 

I have not seen as many problems with coolant hoses, but I did have one airplane that the hoses were absolutely rotten at 5 years, but they did not appear to be Rotax supplied hose. There was a time that the replacement Rotax 90° hose would leak it you didn't also switch to the new Rotax spring clamps. The old spring clamps didn't apply enough tension to seal up, because the wall thickness of the hose was thinner.

A failed carburetor socket can cause a forced landing or leave you stranded. I personally know of two failures. I have removed some pretty rotten looking diaphragms from carburetors, that can also lead to bad things happening. A leaking float needle because it got hard from age can ruin an engine if not caught. I am a little up in the air regarding fuel pumps. 

A lot of times it is just poor quality workmanship and poor choices with material substitutions. Often times the mechanic doesn't know better because they didn't do the research, or they receive some poor advice.

 

[Bill3558]

Thanks for the offer FM.  That very generous.  But I’ve got a couple of years before I’m due. I will figure it out by then. 
 

[FlyingMonkey]

24 minutes ago, Bill3558 said:

Thanks for the offer FM.  That very generous.  But I’ve got a couple of years before I’m due. I will figure it out by then. 
 

Sure, hit me up anytime if you need anything.

[Bulldog]

5 hours ago, Roger Lee said:

Oh Yes.  Tom said it all. It isn't just hose by itself. It's about installations, mechanics, parts, clamping, ect, ect.... Saying it's solely a hose issue is narrow minded. There are many factors.

I agree, and I think that’s why Mike Busch frequently downplays time limited maintenance items and advocates for the least invasive maintenance techniques possible. I’ve heard him talk in the past quite a bit about maintenance induced failures. 

[airhound]

Do FISDO/FAA inspectors check ROTAX repair stations or Flight School (ROTAX) maintenance operations/facilities? Never have seen mention about ROTAX (SLSA) maintenance in general aviation periodicals.. Seems that ROTAX is considered only under Experimental group think….Saw a twin Tecnam with two 912 ULS on the ramp…..I think it must be in the Certified category…IT looks like a mini Aero Commander.  So, who’s checking the checkers ROTAX (QC) in general..?

[Madhatter]

The FAA managers in my FISDO expressed to me they really aren't interested in LSA. The Tecknam P2006 is certified and they must take it seriously. I don't think the P2006  will survive success with just 2 912uls on it, no performance. I couldn't imagine one engine out performance,  probably just take you to the scene of the accident. 

[airhound]

Wow,

Thanking Santa for Tom and Roger and our other knowledgable CTFlier maintainers. It’s a real pleasure to be associated with you all!
 

Wishing us a Merry Christmas and Quality ACI’s in 24

Respectfully,

Doug