5 year rubber replacement

[3kdscf]

If you bought your firewall forward kit from Kitfox, just look at the parts list on that kit and reorder the hoses from Kitfox. I did that for the hoses I was not upgrading and it made the ordering process easier.

Not sure why I did not think of this! Thanks!

[PapuaPilot]

I totally agree with the last two posts. Ten years seems very reasonable. During your condition inspection we should be looking at the condition of the rubber hoses. What should we be looking for? Here is what the Quest Kodiak maintenance manual says about inspecting hoses:
Fluid Lines and Hoses: Inspect for leaks, cracks, bulging, collapsing, twisting, dents, kinks, chafing, proper bend radius, security of attachment, discoloration, bleaching, deterioration, and proper routing. Check rubber hoses for hardness/flexibility and metal lines for corrosion.


Realize that a manufacture, whether certified or experimental, can only make recommendations for maintaining their aircraft. Only the FAA can make something mandatory. Only the FAA can make things mandatory. On certified aircraft the FAA mandates or approves things via AD notes, chapter 2 of a POH "Limitations" and ATA chapter 4 "Limitations" in maintenance manuals.

[109JB]

I would definitely replace the cab boots at 5 years. Hoses can likely go longer but the carb boots have the weight of the carb and air cleaner cantilevered off of them and they do crack with age.

[Jcard]

Purchased a model V with almost 1700 hours and 19 years on the rubber with the exception of the carb boots.
Declined to do a test flight before getting it done, lol.
Probably would be fine but that is pretty excessive.

[Dave S]

My experience reflects the comments that Larry, Jim and Phil have contributed. It's all about condition, how that can be determined and environmental exposure.

After doing my first 5 year replacement, it was real clear that I had taken a lot of perfectly good items out of service.

The carburetor sockets, where I have the airbox installed on the engine, were indistinguishable from the new ones I put in except for the slight odor of 91 octane corn free autogas. I bent and folded the lips of the carb sockets and couldn't find any cracks or any other defects and they were still pliable. Without the airbox, I suspect that vibration and movement can taken a toll eventually, but not sure that would be 5 years - have seen some that were run till they broke after 18 or so years - that's pushing it .

The diaphragms inside the top of the carbs were both pliable and free of cracks at 5 years but you can't see them on preflight.

Still running the original NAPA V-belt on the aux alternator - still shows no signs of deterioration on annual condition inspection. Ditto on the short connector hoses between the airbox and the carbs.

The radiator hoses and heater hoses are pretty cheap anyway. Also - if I do any maintenance disconnecting them (like when the radiator was replaced or the heater repaired) they get replaced anyway. Many times on replacing a hose it needs to be slit to be gracefully removed.

Oil hoses (Parker) were cut open when removed and no cracks or swelling was evident inside or out and all were still flexible.

I have used fuel injection hoses for the fuel lines, same story.

The coolant hoses used on the engine cylinders seem to be pretty tough - replaced them but no flaws found on the old ones.

The fuel pump cannot be viewed internally for inspection so I don't have any problem with replacing that - don't think I would want to test the limit on that anyway (but the old one is retained for a spare.)

On thing is obvious. Rotax does not give a rat's elbow about anything that is not part of the engine. As an aircraft owner/maintainer we look at everything like the vent lines and fuel lines within the airframe and those little sight gauge tubes that need replacement once in a while so me can actually see how much fuel is in the tank.

What is the most troublesome rubber part I have had experience with? That would be those pesky "specialty tires of america" which can't seem to go more than 4, or at the most, 5 years without developing cracks in the grooves down to the cord in spite of careful attention to inflation pressure and the lack of ozone generating equipment in the hangar. I have yet to come anywhere near tread wearout before they had to be replaced due to groove cracks. We'll see how the goodyears last now.

So this year I am doing the 5 year a little later,

Have to agree that an extremely conservative shotgun approach to this deal without regard to use, environmental conditions and actual condition can result in throwing away perfectly good parts and increasing the cost of operation unnecessarily.

[Skipatrol]

I bought a Kitfox finished in 2011 in 2018, with 110 hours on the Rotax 912ULS. Engine now has 455 hours and 10 years of age. I just replaced the fuel and oil lines, and I will soon do the radiator hoses. The hoses were in great shape except for the hose ends. They were rock hard and I had to cut them off with a razor blade knife in order to remove them from the fittings. Oil hoses were 1/2 inch ID transmission hoses, fuel lines were standard 5/16 ID fuel hoses, and some of the radiator hoses are 1 inch ID, all available at local auto parts store. Only hose that I had to order are the 17MM radiator hoses, about $33 for 36 inches. Spent about $150 for all hoses. Five year rubber kits are a ripoff IMHO. I think 5 years is too soon, I am thinking 7-8 years will probably be ok.

[Av8r3400]

I would definitely replace the cab boots at 5 years. Hoses can likely go longer but the carb boots have the weight of the carb and air cleaner cantilevered off of them and they do crack with age.

Use these (Link) and you won't need to replace them every 5 years. Far superior to the Rotax items.

[jrthomas]

Use these (Link) and you won't need to replace them every 5 years. Far superior to the Rotax items.

Yea, I'm a believe in JBM products. I used to have to replace sockets on my CGS Hawk 503 every couple of years. They would always show signs of dry rot within a short time. I went the JBM route and never changed them again. I just recently ordered new JBM carb sockets for my 912. I haven't changed them yet. Annual time is coming up in December and almost 5 years since I completed my model 4 got me to thinking about rubber replacement. I'm inclined to agree that total rubber replacement is unnecessary at 5 years. My main issue is the oil and coolant hoses. I'd like to find a source of good quality hoses but the sizes are hard to find. They are sized in mm and don't cross reference closely to standard sizes. Thanks for all the good advise.

[desertdave]

Use these (Link) and you won't need to replace them every 5 years. Far superior to the Rotax items.

The has to be the most confusing website I have ever seen. With that said I figured it all out and ordered two new carb boots earlier today and got a tracking number within an hour. Thank you for posting it up!

[Maverick]

What is the low-down on carb floats? Being new to Rotax and having an engine put in service in 2008, I'm unfamiliar with all things Rotax.
Fred