5 year rubber replacement-true need?

One frustrating aspect of the hose debate is the lack of data supporting different viewpoints. Maintenance-induced failure is a genuine concern, and removing hoses based on arbitrary age limits has been shown to contribute to such failures. However, there are also cases of hoses experiencing issues and breaking at a young age due to hardening.

We should reject the notion that people de facto disregard their safety by using hoses that are six years old. Savvy Aviation has documented numerous instances of maintenance-induced failure caused by preemptive calendar maintenance instead of on-condition maintenance.

I recently discovered that Rotax engines have a 15-year TBO recommendation, while Lycoming and Continental engines have a 12-year TBO. I am willing to bet that there are more engines flying beyond their calendar TBO than those still within that age range. Should we reflexively follow Rotax's recommendation for replacing rubber parts after five years but ignore it for the 15-year overhaul? Are those flying engines past the engine's calendar TBO not valuing safety?

Another important debate is whether spending $5,000 on hose replacement is the most effective way to enhance safety. Would investing in additional pilot training or biannual inspections yield greater benefits? What if I flew the hoses for 20 years and used the $20,000 savings to purchase a new engine?

It would be helpful if Rotax (or any other company) released data demonstrating the actual risks involved. Until then, following the manufacturer's recommendation becomes an expensive maintenance event that exposes pilots to potential maintenance-induced failures, with only anecdotal evidence and manufacturer suggestions supporting its necessity.

My .02 cents,

I come from a medical back round and a fire department retirement after 30 years. I can't tell you the how many times people are their own worst enemy's and failed points in life with a poor decision. You go to a scene and just shake your head wondering what were they thinking.

I do a lot of rubber replacement work every year and have had zero issues. The comment on expense does carry some weight. I see some places charging way too much and they take way too long to perform the work. You should be able to change all the rubber and hoses on a plane in 2-3 days.and not 2-4 weeks or a hundred hours. It just isn't that tough.

Hose companies like Gate's do failure studies. Gate's recommends 4 years because failures start to rise much faster. Yes we all know many hoses can last longer and if it's on until it gets hard it's WAY past being replaced. Failure rates aren't usually in the middle of a hose. It is usually at the fitting and can be sped up by too much clamping pressure, pushing a hose over a barbed fitting that is already too tight and scraping the inner lining off. Hose placement and inner cowl cooling affect the hose longevity. Can a mechanic install it improperly? Yes, but any maint. done on a plane or any mechanical device can be messed up by the person doing the work. So here education is the key. Yes I did do a small study on where some hoses seem to fail and saw 90%+ have issues at the fitting and not in the middle of the hose where most people say look it's still good I can squeeze it. Now another issue is fuel and oil hoses in the required fire sleeve. You can not inspect a hose for on condition use unless you took all these hoses out of the fire sleeve and off the fittings to see if there is any damage any where on the hose. The damage I saw was cracking on the outside under the clamp or at the fitting end or where you can't see it was on the inside where it went over the fitting and the hose was ruined internally. 

So the bottom line is you have to draw a line in the sand somewhere for everyone's safety and all aircraft uses. . So based on hose Mfg test and studies and in use failure rates from the engine mfg's you need to draw that line on the safety side of the line because you aren't in a car so you can pull over to the curb or call a tow truck. 

So safety first and it isn't just about pilot safety, but passengers and people on the ground if you're forced to land. 

The old saying applies here:

An ounce or prevention is worth a pound of cure. 

Was the work done correctly? Well that's up to you and the mechanic to decide, but don't put yourself at risk or others that fly with you just because you're not a believer in good preventive maint.

So education and training or mechanics and pilots is key to living a long fun life and not a hazardous, painful and expensive life through poor decisions.

Just my .02 cents.

I don't mean to argue, but this post effectively illustrates my point. By stating that deviating from decades-old guidelines for a 40-year-old engine is a poor decision, there is an underlying accusation of indifference. Considering the abundance of available data, we should be capable of demonstrating rubber failure rates without relying on personal stories. It should be possible to analyze these failure rates in relation to various factors such as calendar age, usage patterns, and engine installations (tight vs loose cowling), among others. Until such analysis is conducted, it's understandable that pilots will continue to feel frustrated about spending an engine's worth of money on potentially useless rubber replacements, a non-zero percentage of which will lead to real maintenance-induced engine failures.

@Roger, genuinely curious: do you tear down your Rotax at the 15 year calendar TBO?

All of us who operate these engines attached to our Experimental aircraft, don’t forget to check your Operating Limitations before you decide what to do regarding this topic. Mine state “The aircraft may not be operated unless the replacement for life-limited articles specified in the applicable technical publications pertaining to the aircraft and its articles are complied with…”. It then goes on to give you compliance directions for type-certificated products (generally not installed by us EAB folk, but could be) and non-type-certificated products for Experimental aircraft. It’s a bit tricky for me to interpret but the last sentence is straightforward: “The article must be inspected to ensure the equivalent level of safety still renders the product in serviceable condition.”  So have a look at your limitations as should you decide to replace engine rubber on condition rather than on calendar, it may be prudent for you and your estate to document a regular maintenance inspection program for those articles.  You may want to base it upon the rubber manufacturer’s technical data. That holds up well in front of the lawyers. 
I once was introduced to a man who had built a little Zenith STOL like mine many years ago and was flying it from his property. I could smell fuel as I walked up to the aircraft and as he showed around the plane, when he opened a cabin door a rush of strong fuel odor greeted me. Having restored many old cars I recognized the smell of fuel vapor emanating from old, brittle, fuel-soaked hoses. I asked him if he’d ever replaced any of them since completing his build so long ago. “No” said he. He then offered me a ride. I politely declined. 

Quote, "@Roger, genuinely curious: do you tear down your Rotax at the 15 year calendar TBO?"

To me this all depends on the owner and mechanic that takes care of the aircraft and how they document.

No. Here in the US the FAA has two legal documents out. One from 2011 and the other from 2013 that says you are allowed to use a program that is approved by the regulatory authority. The program is on condition and the regulatory agency is the FAA.This statement is in the FAR's at the end of the TBO documentation. I have friends with 3k - 4K hours on their engines and have done nothing, but the prescribed maint. in the manuals and do nothing to ruin their engine by deviating from that thinking they are smarter than Rotax engineer's. 

Food for thought;

It doesn't seem strange that a certified aircraft can go on condition and a Light Sport Rotax engine that is better, newer in development and a far better track record in the its later years has people up in arms that the TBO for time and years must be followed?

This will be different from country to country. Check you  own regulations.