What's new
Van's Air Force

Don't miss anything! Register now for full access to the definitive RV support community.

Coolant hose chafing

An Alternative Solution

After some discussion with John Peck, I added two Adel clamps, a year ago or so (back to back), after observing some chafing.

AdelClamps.jpg
 
When I built my 12 I used RTV on all the potential chafe points. It's standard practice so I'm surprised the plans didn't just include a general statement to look for chafe points on all hoses and wires.
 
Did the same

Seems like the E-LSA must have a higher standard to comply with. This is a very common issue on all aviation engines.
But it is a great reminder for everyone. The nice thing with the E-LSA I guess is that we all will have the same problem where most E-AB's are different.
There are many places on my IO-540 that have the same issue with the same prevention technique.
 
New firewall forward kits

The SB doesn't apply to newer firewall forward kits after 2/13/12. Does anyone have the background on that? (would assume that checking for chafing should be standard on any inspection checklist) Or is it that Van's is/will write the SB directly into the builder plans?
 
ScottSchmidt said:
The nice thing with the E-LSA I guess is that we all will have the same problem where most E-AB's are different.
Click to expand...

Great point Scott, too often people focus exclusively on the constraints of the E-LSA type without realizing it's benefits. E-LSA is a kind of "Certified light" type, no pun intended! :D
 
2013, not 2012

PilotBrent said:
The SB doesn't apply to newer firewall forward kits after 2/13/12. Does anyone have the background on that? (would assume that checking for chafing should be standard on any inspection checklist) Or is it that Van's is/will write the SB directly into the builder plans?
Click to expand...



Affected Models: All flying RV-12 aircraft and RV-12 Powerplant Kits
shipped prior to February 18, 2013

Alan
 
PilotBrent said:
The SB doesn't apply to newer firewall forward kits after 2/13/12. Does anyone have the background on that? (would assume that checking for chafing should be standard on any inspection checklist) Or is it that Van's is/will write the SB directly into the builder plans?
Click to expand...

The check and remedy proceedure will be in the construction manual from that date on so complying with the S.B would be redundent.
 
I suppose I have too much A&P blood running in my system, but it just seems to me that even if not noticed before the AW cert, somehow in 750 hours someone should have noticed that there was a problem.
 
Your right Don... anyone that would take any time to look back through your hundreds of posts about building your RV-12 would see that it is obvious you do everything perfectly every time ;)



More to the point...

This type of problem can happen at very different rates, from one airplane and another (even if they are built exactly the same, as most RV-12's are)
Prop. balance, overall airframe vibration, etc. can be major factors in the rate that this occurs.

Don't assume that hose wear has been present on the prototype (or will be on other RV-12's) after only 50 or 100 hrs. The point of teh S.B was to alert all RV-12 owners that it can occur, and you should look to see if it is.
 
Apparently there is a Rotax requirement to replace all rubber hoses on all 912 equipped SLSA planes after 5 years in service. Don't know if it applies to ELSA's or not. A local SLSA equipped with 912 met this requirement and the hoses were replaced. $800? The trouble was that in the process a black tie wrap was used to secure one of the radiator hoses. It melted during flight and let the hose contact the exhaust pipe which melted thru dumping the coolant. Luckily when the temperature alarms went off it happened near the airport. Be sure to use clamps as shown by Marty's photograph!
 
Coolant Hose Meltdown

During my 100 hour inspection I checked for hose chafing as per the SB. The water supply line was in direct contact with the exhaust for cylinder #1. The hose melted almost all the way through. I was probably a couple of hours from a complete coolant dump.

Has anyone seen this specific problem?....it was mentioned earlier in this thread. The Rotax illustrated parts catalog calls for a heat resistant sleeve over the supply lines for cylinders #1 and #2 but this was not included in the powerplant kit.......?:eek:

Thanks,

Bob
 
Bob Ross said:
During my 100 hour inspection I checked for hose chafing as per the SB. The water supply line was in direct contact with the exhaust for cylinder #1. The hose melted almost all the way through. I was probably a couple of hours from a complete coolant dump.

Has anyone seen this specific problem?....it was mentioned earlier in this thread. The Rotax illustrated parts catalog calls for a heat resistant sleeve over the supply lines for cylinders #1 and #2 but this was not included in the powerplant kit.......?:eek:

Thanks,

Bob
Click to expand...

Cyl 1 is the right front. Is that the one you mean?

The sleeve you mention is not a standard part delivered with new engines, but it may be used in some OEM installations. It costs about $200.

The SB was looking for chaffing of hoses on the engine mount. A standard RV-12 engine installation shouldn't result in any hoses being anywhere near close enough to touch the exhaust system.
 
Yes, the hose I am referring to supplying water to Cyl #1 (right front). The hose passes behind and is against the exhaust pipe for Cyl#4 (right rear). Perhaps I don't have it routed properly but it can already attached to the engine. Can someone send me a photo of the proper installation?

Thanks, Bob
 
Picture for discussion

Here is a picture of mine. I'm not sayin' its right, but offer it as a discussion point. The blue tie-wraps are high temp Tefzel, available from Stein Air and others:
The number 1 coolant hose actually clears the exhaust without the tie wrap but is real close to the spring so added the tie-wrap.
P1030051-M.jpg
 
Thanks Tony. That is very helpful. I think I know what may be going on. I may have positioned the muffler and exhaust pipes too far to the left side of the airplane. If you remember this lateral adjustment is required during the installation process. Ill check on this.
 
Bob Ross said:
Thanks Tony. That is very helpful. I think I know what may be going on. I may have positioned the muffler and exhaust pipes too far to the left side of the airplane. If you remember this lateral adjustment is required during the installation process. Ill check on this.
Click to expand...

Bob, that was what I was going to suggest. The nominal design position is exactly centered under the engine.
 
RV-12 How much clearance is enough?

Guys, I'm seeing about 1/2" between #1 coolant hose and right rear exhaust. I can shift the muffler further to right but may need to move/re-glass the exhaust hole in lower cowling. So, move it or is 1/2" enough? Your thoughts?
Thanks!
Dave
 
If you are concerned why not use some insulating wrap? I did that on my oil hose below the forward right cylinder.
 
Can you use one of the rocker arm push rod tubes on the bottom of the cylinder to create a stand off to move the coolant hose a little farther away? They don't get very hot.
 
What are others seeing for clearance?

Thanks Rich, I guess my question is "Should I be concerned?" What are others seeing for clearance with no problems?

John, I thought about using one of the lifter tubes also. May try that if the consensus is that more than 1/2" is needed.
 
Dave,

I have the original location of the muffler prior to moving it aft. I don't remember any concerns on this, and after 350 hours and 3 1/2 years I have had no problems. Can't comment on the new exhaust positioning.

Go to NAPA or Auto Zone and buy some cheap piece of mind with insulation wrap!

Rich
 
So long as you have an air gap you are usually just fine, but anytime I'm within an inch of an exhaust pipe I always put on a piece of cut fire sleeve or some other rated heat barrier. Plastic wire ties will work just fine holding these in place.
 
I just replaced these coolant hoses. Not for cause though, it was a 5 year replacement. I think the #1 bottom hose is too close to the #3 exhaust pipe for comfort. The top hoses came off looking good. The bottom hoses especially that one probably should be changed for sure on the 5 year schedule as they all are subject to a lot of heat. Also the bottom hoses are comparatively easy to change, compared, that is, to the top ones which are a b****.
i-fg6HChd-L.jpg


I push it back toward the engine case and use a couple of tie wraps to the #3 coolant hose to hold it away from the exh. pipe. You will have to cut the tie wraps to push the hose aside to torque check the bottom right engine mount cap screw.
 
Coolant Hose Clearance

Awesome Guys, great input!
Thats what I was hoping to get is some wisdom from the "experienced aircraft".
Thanks,
Dave
 
You must log in or register to reply here.
Back
Top