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Jerry

Leaking hose clamps in the winter

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When the weather turns colder, after each flight there's a small amount of aintifreeze sitting on the ground under the coweling of my CTsw after the engine cools down.   This never occurs in the spring, summer, or fall months.

Last year I tightened up the hose clamps as tight as possible with out causing damage to the hoses and that had a slight effect.   Then I changed out some of the clamps which were identified as being the leakers and again that helped a great deal but no cure.

 

The engine doesn't start leaking until it has full cooled down which leads us all to the problem lying with different rates of expansion and contraction between the rubber hose and the metal pipe it's secured too.

 

Questions:

1. Does anyone else have this problem?

2. Is this normal and I just have to live with the mess? (i hope not)

3. Anyone know of a recommended clamp that will solve this problem?

 

As always, I appreciate your input.

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When the weather turns colder, after each flight there's a small amount of aintifreeze sitting on the ground under the coweling of my CTsw after the engine cools down.   This never occurs in the spring, summer, or fall months.

Last year I tightened up the hose clamps as tight as possible with out causing damage to the hoses and that had a slight effect.   Then I changed out some of the clamps which were identified as being the leakers and again that helped a great deal but no cure.

 

The engine doesn't start leaking until it has full cooled down which leads us all to the problem lying with different rates of expansion and contraction between the rubber hose and the metal pipe it's secured too.

 

Questions:

1. Does anyone else have this problem?

2. Is this normal and I just have to live with the mess? (i hope not)

3. Anyone know of a recommended clamp that will solve this problem?

 

As always, I appreciate your input.

This is a common problem. Keep tightening the clamps and normally after a while everything seats in and the leaks really slow down or stop all together. The Folks at Flight Design USA told me they have a different hose and clamps that they have been using with good results.

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When the weather turns colder, after each flight there's a small amount of aintifreeze sitting on the ground under the coweling of my CTsw after the engine cools down.   This never occurs in the spring, summer, or fall months.

Last year I tightened up the hose clamps as tight as possible with out causing damage to the hoses and that had a slight effect.   Then I changed out some of the clamps which were identified as being the leakers and again that helped a great deal but no cure.

 

The engine doesn't start leaking until it has full cooled down which leads us all to the problem lying with different rates of expansion and contraction between the rubber hose and the metal pipe it's secured too.

 

Questions:

1. Does anyone else have this problem?

2. Is this normal and I just have to live with the mess? (i hope not)

3. Anyone know of a recommended clamp that will solve this problem?

 

As always, I appreciate your input.

 

Same thing happened to me this year (my first year with my airplane).

Once I tracked down the source, I wiped the area clean, tightened the clamp and after an engine runup test, the coolant seep disappeared.  Hasn't reappeared since.

 

This is just a suggestion, but personally, as part of my preflight inspection, I like to remove both engine cowls, to gain a better view of the entire engine area.  In doing so, I inspect the inside of the bottom cowl for telltale signs of any leaking/seeping fluids.  The inside of that bottom cowl is a great "catcher."  I am also an advocate of keeping the engine area squeeky clean.  Why?  If gives a much better indication of any leaks/seeps developing.

Some may think that is a little overkill, removing the bottom cowl, but that is the way I have always done it and it has worked out pretty good so far.  Just remember . . . to reconnect that landing light! . . . :)

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Last year, my first year of ownership, when it got cold I sprang a bunch of leaks.  I clamped everything down really well and added a couple of secondary clamps, and this year I have not had a recurrence. 

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Hello Jerry

 

My CTLS leaks small amounts of coolant on to the hangar floor each winter ( Sydney Australia )

Checking all hose clamps never seems to fix the problem completely.

It would be nice to hear from the people in the know about this unacknowledged problem.

As long as the leak is no more than a few drops I don't worry about it anymore.

 

Greetings from "Down Under"

 

Niels

 

VH-NKO

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I have the same issue. I don't know if it is the clamps or the seal that Roger has spoken of. I tightened things last year with little effect.

I think it is good practice to check the expansion tank (as well as the overflow tank) as a part of preflight when this is happening.

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If it's leaking from the coolant pump seal there is nothing you can do a Rotax says this can be normal. It usually happens during the winter with the cooler OAT.

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Thanks everyone for your suggestions, I was just glad to hear that I wasn't alone.   This is my second winter with the CT, last year I had the same problem and like most of you, I tightened the clamps...a couple of times before it stopped leaking.     I worry about tightening the clamps too much for fear of possibly compramising the hoses and creating a new problem.    I like the double clamp idea, that will be this year's solution.

Thanks again guys!

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Believe it's been stated before but there are new, wider and different designed clamps available for this concern. These have a telescoping sleeve which is kind of like a clamp within a clamp. There is also new coolant hose which is thicker. Mat at FD can provide these and I've been told these are also available at outside of FD USA.

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Believe it's been stated before but there are new, wider and different designed clamps available for this concern. These have a telescoping sleeve which is kind of like a clamp within a clamp. There is also new coolant hose which is thicker. Mat at FD can provide these and I've been told these are also available at outside of FD USA.

Dick,

Any commercial weblink for those clamps?

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Hi Dave. Thanks for providing the type of clamp. These worked well on the CTLS that Hillsdale Aviation repaired.

 

Bill, I don't have a link but I'll check on this.

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I have the same leaking problem with my 912 and 912S on EUROPA aircraft and when I buy my CTSW.  These leaks are due to temperature expansion > winter > summer.

 

It is necessary to replace the screw clamps by spring clamp after you have no leaking problems.

 

Spring Band Clamps - Mubea 

 

they sales all dimensions and small quantity.

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If spring clamps and the RIGHT worm drive clamp (Wurth, see maint. pictures on our forum) is applied in the correct location you will not have any leaks. The spring clamps should be placed on the hose up by the flared end the metal tube under the hose. Standard worm drive clamps with the serrated holes should not be used and certainly not on fuel lines. These clamps seal poorly under the flat area under the screw and can over cam to easy when tightened too much. Placing clamps too far back away from the metal tube flares allows clamps to leak more easily. After clamps have been applied a few months and certainly by 100 hrs. the screw drive clamps should all be tightened because the rubber hose settles. In cold climates this is very important because of more expansion and contraction of hose and underlying metal tubing. Using some clamps with the wrong hose also lends itself to leaks.

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Hi all, I seem to have a similar problem with cooler temperatures in winter. There seems to be a leak on the constant tension clamp joining the rubber hose coming down from the expansion tank to a metal bent pipe. Does anyone think that this is ok and ignore as during flight it will be warm and hence tight due to expansion or should I maybe consider having the constant tension clamp replaced? I will have it inspected by my engineer but wonder whether anyone has managed to stop it when constant tension clamps are used already, which would be a great guidance.

Thanks, Matt

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Hi Matt,

 

Extreme cold can cause this, but just cooler weather shouldn't. Make sure the clamp is right up against the raised area on the piping under the hose. Too far back causes leaks. Do not place the clamp right on top of the raised part of the piping. If it still leaks replace the clamp. If it leaks after that use a Wurth wormdrive clamp on the hose. 

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Hi Matt. here's some additional info to Roger's recommendation.  This comes from my friend Phil, the other CT owner who I fly with.  Phil  has had recurring coolant leaks ever since he had the rubber change a few years ago. After many tries to stop the leaks, including using the Wurth clamps Roger recommends, Phill called FD and spoke to Arian.  In response to Phil's concern, Arian and Phil arranged to install newer, thicker wall hoses and new, Tridon Smartseal, hose clamps on Phil's CT.  The thought was that the older coolant hoses have thinner walls and offer no cushion to account for the cold shrink.  By using the thicker walled hoses with the Tridon Waveseal clamps which have a double ribbed inner sleeve, there should be cushion to keep the seal when shrink occurs and the clamps were supposed to provide 360 degree tightening of the hose.  This didn't totally fix Phil's leak problem and he continues to have coolant leaks in cold weather.  Our mechanic even doubled up the clamps, trying to stop the small leaks still coming from some of the hoses. The clamps were placed in many different locations - up near the upset @ the end of the tube, etc., but still didn't stop the leaks.   As you point out, with warmer weather or as the engine heats up, the leaks go away.  There are various versions of "constant tension" clamps.  There are the Tridon screw clamps which FD supplied to Phil and there are the "spring" clamps which have the two ears which Rotax now uses on their latest engines.  Phil has since talked to Arian at Sebring regarding his continuing coolant leaks.  Arian said that the problem is that the coolant tubes and hoses expand and contract at a different rate than the stainless steel screw clamps.  In cold weather, the aluminum tubes and rubber hoses shrink at a different rate than the steel clamps, tension is lost and leaks occur.  From the information I have, the double eared, spring clamps, which Rotax now uses on new engines, is the recommended hose clamp. The theory is that these exert a clamping tension on the coolant hose regardless of temperature.  So, the last I checked, FD's position on this is to use a thicker walled coolant hose, which perhaps Arian might be able to provide the type or stock number, combined with the spring clamps. 

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Hi Roger, hi Dick, thank you for your replies. The temperature recently dropped to about 37 deg F overnight and maybe it was cold enough? As cold as it gets here. The clamp seems to sit near the raised part, but maybe it needs reseating. Will have a look at it.

Here is an image of where I think the leak occurs. Thanks again.

Matt

IMG 1690

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To make things easier just add a second clamp where you can reach it. The tubing at times is not perfectly round on some of the bends and if the clamp isn't right up against the flared part of the tubing it will leak. Just add the second clamp. Don't make the fix harder than it has to be. 

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