English French German Italian Portuguese Spanish Swedish

rotax brp


Wednesday, 19 December 2012 12:28

The Task at Hand; Rotax 5 Year Rubber Replacement (Part 1)

Written by Rotax Owner

Part 1

This discussion is going to focus on a topic that will undoubtedly have Rotax engine owners on both sides of the fence, both for and against in a major discussion, but I hope to instill a sense of “Doing things right and for the right reason” and without all the worry some seem to have over this solid and sound maintenance practice. As you can see from the last few words in the last sentence this article will focus on the positives and good maintenance practice and hopefully get away from the all encompassing “Don’t fix it if it isn’t broke” concept. I do believe that some items are fine to be on a condition inspection or even wait until it wears out, but those are not flight safety issues or will they present a hazard when they fail. Planes in general and the hose change cost money , I’ll be the first to admit that, but you decided to fly and now you need to ask yourself what your life and your passenger’s life is worth and do you want to spend a little money now and keep safe and flying or spend a lot later and be grounded?

The Rotax Line Maintenance manual dated 09-20-12, Section 05-10-00, paragraph 2.1 and subject head “Time limit for rubber parts” is the section we will be addressing in this article. There are two important issues here to cover. First is the issue with hose time limits and how long will a rubber hose last? The second and possibly more important is hose selection and the right way to install a hose which is covered in part 2 of this article.

Many of the machines we use now days in a high risk environment have some type of maintenance program the manufacturer wants followed and some are mandatory. Even our automobiles have a recommended hose, serpentine belts and V-belt replacement program. Some owners are good about following these practices and of course we see some autos stranded on the side of the road or even a damaged plane in an off field landing and these folks may not have been as good about their maintenance practices. Even with a good maintenance program mechanical parts and hose can and do fail. The whole idea is to put the odds in our favor and not test the limits.If we are in our auto and have a hose failure we can pull over and call for assistance. If we are flying in our aircraft then a hose failure is probably going to bring you and possibly a loved one down in the worst possible area. Do aircraft hoses fail before their time? Yes they do and have caused many an aircraft emergency. With that in mind many aircraft engine and aircraft manufactures in general have recommended time tables to which they recommend a hose maintenance program which is usually backed up by 20-60 years worth of data and failures not to mention the recommendation right from the hose manufacturer themselves. The bottom line is Rotax and others are trying to error on the side of safety and not test the limits of each hose within the hostile environment in the engine compartment as you are flying over the Grand Canyon. If you are one that says don’t fix it until it breaks then you may be willing to switch sides as you glide down into the Grand Canyon that has no landing areas and a has the fast running Colorado river.

Many aircraft manufacturers now recommend that you follow the Rotax 5 year rubber replacement program. So how long is oil, fuel and coolant hose good for? The answer is, who knows for sure. Could it last only one year before a failure, yes. Could it last ten years before a failure, yes. No one can ever tell you exactly when a hose may fail so we use decades of observance and factor in some safety and make our best guess for you to get to that point and not have an issue. Over the last several years we are seeing a huge increase in owner compliance with the hose replacement program and that’s good news, but too many have had hose particles reaching the carbs and causing a power reduction.

The immediate response has been that it must be bad hose, but in 98% of the cases it has been mechanical damage from poor installation practices and possibly poor hose choices. There have been a few pieces of bad hose and Rotax issued a Service Bulletin for the fuel pump hose because of that very issue, but that is usually very rare compared to the amount of hose actually sold and used. Let’s look at the hose time table for replacement. Many want it to be a condition inspection replacement item. Okay so what are your replacement limits? Is it when the hose gets hard? That’s too late in the game. What about the fuel and oil hose in the fire sleeve? Do you dismantle all that hose and pull it all out of the fire sleeve to inspect it? I know of no one that does that. While you are looking at the outside what about the inside that begins to flake or degrade from time? How do you inspect that? How do you inspect the hose for cracking and separation under the hose clamp at the edge of the fitting on the inside and outside of the hose? (This is the most common problem area.) How many of you have been trained by a hose manufacturer to know even what to look for or were you just taking someone else’s word for your education?

So looking at it from a safety stand point, none of us are hose experts or have all the data the engine and hose manufacturer have so it just makes good common sense to error on the safe and practical side for you and your passenger’s safety. I would like to mention one other item here and look at it from a legal burden which none of us hopes to have to encounter. If you have someone in the plane with you and go down because of a hose failure and it is past the aircraft and engine manufacturers recommend rubber replacement time and the other person or other person’s family member takes you to court I would hope that you can back up all the good solid reasons that you didn’t do the recommended maintenance because it will be brought up and your hose expertisewill come to the forefront. Family members and their lawyers are not very forgiving. That alone is enough to scare me because I have been to those types of court cases for over 30 years. If you error on the right and safe side it is much easier to defend from a legal standpoint.

Read 18293 times


# It may still be a trade-off judgement callAl C 2012-12-20 18:32
RE: 5 year rubber replacement, it said "you need to ask yourself what your life and your passenger’s life is worth and do you want to spend a little money now and keep safe."
Safety is everyone's highest priority. Safety is relative, and so is "little" cost.

Here it's estimatedrubber replacement can exceed $3500.
Ohter question is "are there _other_ things a PARTICULAR owner can do with $3500 that might add MORE safety? Training? Better avionics? BRS chute? Etc?
# mandatory means?Barry Windle 2012-12-20 19:02
Where is there discretion/choice in "mandatory"?
# built-in obsolescence is part of this, tooJohan Prins 2012-12-20 22:26
I am not surprised about the 5-year rubber replacement initiative, but I am sad that everywhere, rubber parts have a shorter lifetime than they used to have. Even engine mount vibration dampers suddenly die in a few years.
I suspect a system behind this.
# Silicon engine hosesStefan Ingemarsson 2012-12-21 01:17
Hi it could be good if we can buy a rubber-kit without any engine cooler hoses for the 4 stroke 912-914. I have now flying with blue silicone hoses at the engine for 6-7 year and about 600 hours. EAA in Sweden/Norway and a lot of other country say´s that silicon hoses are under condition. Absolutely no problem at all.
# Maybe, maybe not.....Robert Bogash 2012-12-21 10:49
I'm neither for nor against the 5 year rubber replacement. But, I AM skeptical about some of the comments.

For starters, I don't have much confidence in the engine or airframe manufacturers coming up with any scheme that makes sense - they are ruled by lawyers who just want them to cover their backsides. You said as much in your own question about being sued after an accident - CYA to improve your legal defense. (Not likely, by the way.)

They also like to sell product - spares are often much more profitable than the original parts cost.

You raise a lot of good questions, and imply there are not a lot of good answers - like how long is long enough? I don't have confidence in manufacturers knowing the answer (maybe the hose guys do, but the engine and airframers probably don't.)

The recent Rotax fuel line SB (and EASA AD) demonstrate an amazing lack of both awareness and product and supplier control on their part. Imagine spec'ing a fuel hose that is not compatible with fuel???!!!.

I'm not a big believer in "erring on the "safe" side." What's the "safe side"? I prefer facts and data. Time and temperature testing data. Something besides arm waving.

Round numbers make me nervous. Why five years? Why not four years? Or three? Why no mention of service hours, or conditions (the car companies have variable recommendations depending on circumstances, dusty conditions, trailer towing, etc.) Different planes have different cowling and cooling situations. Would you be as eager to comply if Rotax demanded an Annual rubber replacement program?

I've been working on airplanes for over 50 years and enjoy Mike Busch's columns in the EAA mag. He's a minimalist, and provides facts and data, and backs up his beliefs by signing on the dotted line (as the certifying A&P.)

Fact is - you could be removing a good part and installing a defective one. You could screw up the installation of a good part. Breaking into satisfactorily functioning systems is always fraught with danger, and bad things often happen - sometimes on the first flight after maintenance.

There is much to be said for the "If it ain't broke" mantra. Air carriers and the Part 25 Transport airplane crowd learned this long ago, and moved away from Hard Times to O.C. (On Condition) schemes decades ago. Some 737s are passing 40,000 hours with the same engines still on the wing - over 10 years since leaving the factory flying 10 hours/day. Their safety record has not declined - it has improved!

I don't mind spending the bucks or taking the time - but only if it's the RIGHT thing to do - not to make some lawyer or accountant or bureaucrat happy.

Just saying.....

Bob Bogash
RV-12 N737G
# Who says it is required?Johnnie Poole 2012-12-21 22:31
The Type Certificate Data Sheet for my Remos GX is very clear that Rotax claims the tubes and hoses must be changed each five years, but that it is not required on Remos aircraft, but recommended.
So now the owner (me) is in a real quandary. I paid handsomely to change the rubber out on my 2007 Remos G3/600. I have carefully examined each removed part and cannot find a single hose that was stiff,cracked, deteriorated or any way distinguishable from the new article.
The exception is the carburetor spacers. They probably were stiff, since the performance improved after replacement.
Therefore, on my new 2011 GX I will carefully inspect the hoses using the criteria of AC 43-13 for cracking, stiffening, weathering, etc and replace only the carburetor spacers (rubber sockets).
I believe I could successfully use those documents plus my 40-plus year corporate maintenance career inspecting such hoses on a regular basis to defend myself in any lawsuit.
You can too, if your airframe manufacturer has the hair to state their position as clearly as Remos has. The problem, as we all know, is that most manufacturers don't give a rat's empennage about owner maintenance costs. They only care about sales, not resale value.
It really is up to us as owners to challenge these dubious requirements. I especially dislike being bullied by reference to the legal aftermath of a crash.
Make your own reasoned assessment of the operating environment of your airplane. If you are operating an un-cowled Rotax engine on an aircraft that is stored outside of a hangar in the desert, you need desparately to change those hoses! Otherwise, the age-old pitchman's caveat of "Your mileage may vary!" certainly applies.
# pjsowePeter Skurla 2013-01-18 03:27
If rubber parts have such a short life of only 5 years I am very surprised that there is not a specification on source certification of shelf life from date of manufacture to installation. A rubber part could be in the supply chain for several years prior to first installation. I am very suspect of all of this 5 year life on rubber. Are Lycoming and Continental under the same restrictions?
# Safety, unfortunately, is ALWAYS traded off against costAllan Spensor 2013-06-02 08:24
Quoting Skyranger2:
RE: 5 year rubber replacement, it said "you need to ask yourself what your life and your passenger’s life is worth and do you want to spend a little money now and keep safe."
Safety is everyone's highest priority. Safety is relative, and so is "little" cost.

Here it's estimatedrubber replacement can exceed $3500.
Ohter question is "are there _other_ things a PARTICULAR owner can do with $3500 that might add MORE safety? Training? Better avionics? BRS chute? Etc?

Good point.....
If a complete rubber change-out is going to cost about the same as adding a BSR chute, and you can't afford both (how many of us are "price is no consideration" owners), can you really say the rubber change out adds more to your safety than the BSR?
There are ALWAYS more things, and money, we can add to safety and "just in case" insurance. If no risks are acceptable we shouldn't even be flying private aircraft at all.

You must log in to post comments