Radiator Mount Cracks

Radiator Mount Cracks

  • I have examine my aircraft and yes I found one or more cracks.

    Votes: 6 23.1%
  • I have examined my aircraft and found no cracks.

    Votes: 10 38.5%
  • My radiator is mounted in some other way. N/A

    Votes: 7 26.9%
  • I have not yet examined my radiator mounting.

    Votes: 3 11.5%

  • Total voters
    26

Joe Pires

star hoarder
Joined
Jan 16, 2006
Messages
2,901
Location
Geneva FL FD92
Aircraft
Aviomania GS2.
Total Flight Time
600 ish solo gyro and 190 ish two place
Larry, Penguin, posted a thread recently about the cracks he found in the supports that hold the Dominator radiator at the bottom. After reading that thread I checked more closely and found both of mine had the cracks and Ed Lemoine's did as well.

The thing that has me curious is that I didn't see many others with this issue. So if you don't mind if you now own a Dominator please respond to the poll.

Ed and I both operate regularly off grass fields and do the occasional "off airport" landings. But Larry as far as I know operates off hard surface runways mostly. Just trying to get a feel for the problem.
 
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Awh nuts!
I done lost it?
Guess my vote don't count!
 

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I guess we might as well let this stay open till Bensen Days is over. Some of you cold weather guys might not be seeing your gyro as much this time of year.
 
Joe - Good idea.
If you talk to me REAL NICE, I might let you take a gander at my new radiator and mounts.
$75 and picked up maybe 4mph WFO.
(But it is Not Approved By Ronnie!)
 
From an entire universe of 12 who participated in this poll and who have their radiator mounted as specified, 5 have found cracks. Rounding up to a whole number, that makes 42% of those reporting finding cracks.

I heard some comment about it being caused by out of balance props. 1. No one has inspected the aircraft to see if in fact the props are out of balance. 2. Even if it was the cause, if 42% of this model gyro can expect to have out of balance props then the mounting system should be accommodate it.

The two solutions that I have heard about so far are 1. to add a gusset and doubling at the site of the break which is how Edypaul fixed his and mine. 2. To mount the radiator in a completely different way, eliminating the long arm.

Penguin seems to have a good idea, although he is in the test pilot phase still so you might want to have him continue his experiment to see if he finds any unintended consequences.

In any event it would seem to be a great idea to be extra vigilant in the inspection of this component.
 
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Radiator Mounts

Radiator Mounts

I am in the process of purchasing Jamie Cleary's Dominator. I will ask him this evening if he has looked at the brackets and report back. I like Penguin's solution although it does'nt look like he gained that much in temperature however the improvement of airflow seems to be worthy. We will see how his mounting system holds up. I thought you could buy thermostats with different temp ranges?????
 
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Thermostat

Thermostat

You can for your Ford or whatever.
I have searched but can not find a 582 thermostat in a different range.

Wow, that's strange, maybe that's how Rotax gets so much for theirs, maybe it's a one-off design that they have made special and they need to recoup their investment ( it does happen). :usa2:
 
I inspected mine, no cracks found. Plenty of hours on the airframe too.....

Rotax blue head 582 ( and 618 ) thermostats are a two stage thermostat.... The engines are designed with two coolant paths, one that bypasses the radiator all together, and another that goes through the radiator. The thermostat controls which path the coolant takes, making it a more complicated piece and therefore more expensive. The idea is that when you start the engine, the coolant only circulates through the engine itself, which speeds up the warm up of the coolant... once the coolant inside the engine is up to a certain temp, the thermostat will slowly open allowing the coolant to go through the radiator... of course as that coolant enters the engine the thermostat closes until that water heats up, then reopens, more flows in, closes, heats up, etc.... till all the coolant is at operating temp.

It does this to keep the temp of the coolant going through the engine stable.

My Yamaha sled engine conversion uses a very simular two stage thermostat and dual path coolant routing.

My experience with several blue head 582 and 618 engines, is they tend to run at around 125-145 degrees once fully up to temp. I think Penguin is wanting to run his hotter. I believe Rotax says one thing in some of their manuals, yet the way they designed the engine and thermostat it does another... I have seen the same temps out of these engines mounting in pusher or tractor config, and with small rotax " twin radiator " set ups, smallish single piece radiators, and of course the radiator common on most gyros, the VW rabbit radiator.

Even my 120+ HP four stroke yamaha engine, fully warmed up, the coolant never gets above 145 degrees.

I have no explaination about these cracks a few have found. Perhaps since most of the people who found them live in florida, a state known for corrosion of aircraft due to all the humidity salty air, it may be a issue of corrosion? Could be improperly welded from RFD as well? I don't know....

I do know that on my last piper, it had steel wing struts and part of the annual inspections was to remove the struts and check the inside of the tubing for corrosion, and before putting it back on the plane, the mechanic poured Linn seed oil into the strut and the strut was rotated all different directions to coat the inside of the tube with this oil. Ive often wondered if we shouldn't be doing something like that to the insides of all our steel tubes on our gyros....
 
radiator mounts

radiator mounts

I spoke with Jamie Cleary last night and he said he did not find any cracks on his Dom, however he only has 45 hrs on the machine.
 
I think Penguin is wanting to run his hotter. I believe Rotax says one thing in some of their manuals, yet the way they designed the engine and thermostat it does another...

I totally agree with Ron and have alluded to that elsewhere.
I've tried to find a knowledgeable Rotax tech who can explain this dissonance without success.
 
I have no explaination about these cracks a few have found. Perhaps since most of the people who found them live in florida, a state known for corrosion of aircraft due to all the humidity salty air, it may be a issue of corrosion? Could be improperly welded from RFD as well? I don't know....

Here Ron and I part ways.
(Thankfully. Things are back to normal.)

There is ABSOLUTELY NO CORROSION, externally of internally on my failed strut.
The problem, is simple - the lower radiator mount is a long moment arm, with a small contact surface weldment. IMO, every one of them will eventually fail.

I have seen big glob job welds and gussets for repairs. I think it would be a straightforward repair to eliminate the lower mounts and replace with a piece of aluminum stock secured to the vertical engine supports with Adel clamps. Simple, light, and effective.
 
I was just throwing out two possible causes.... My machine has nearly 300 hours on it and no cracks at all.
 
I was just throwing out two possible causes.... My machine has nearly 300 hours on it and no cracks at all.
We do not all fly with your style and grace Ron.
 
Ron:

Yes, you should put either warm linseed oil or proprietary tube-sealing oil into welded-tube structures. The most serious rust-out problems naturally occur at the "downhill" ends of tubes, such as the aft ends of longerons on taildraggers.

The "hangar wisdom" I've heard about thermostats is to leave 'em out in 2-stroke cooling systems. The theory here is that warming the engine up using the radiator bypass circuit will result in a rush of cold coolant, and possible cold seizure, the moment the thermo opens.

I used no thermostat and a Rabbit radiator on my 912S, however, and it was way too much cooling on a cold Vermont winter's day. It wouldn't get above 95 until I blocked off most of the radiator with plastic and Ductape. I didn't have this problem with the 618 using the same radiator.
 
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The "hangar wisdom" I've heard about thermostats is to leave 'em out in 2-stroke cooling systems. The theory here is that warming the engine up using the radiator bypass circuit will result in a rush of cold coolant, and possible cold seizure, the moment the thermo opens.

Possibly true for the grey head but not for the blue head which has a special circuit and a 2-stage thermostat designed to eliminate cold in-rush.
 
Alternative Dom Radiator Mount?

Alternative Dom Radiator Mount?

I mentioned elsewhere that replacing the Dom's long moment arm lower mounts with a cross member secured by Adel clamps is almost exactly what the Air Command uses.

The following pic is of Art Irvine's Air Command and illustrates what I had in mind ...

picture.php
 
We do not all fly with your style and grace Ron.

Ive had my share of bad landings... you remember Bensen Days 2011 when I landed so hard my keel flexed enough that the prop cut one of my rudder cables during the spot landing contest?
 
Doug, the radiator on my Titans 912 is TINY! Its maybe a foot across and 8 inches tall.... It struggles below 50 degrees OAT to allow the coolant to get to the minimum for flight ( 120 degrees ) I usually tape it nearly shut.
 
I've crossed 600 hours and have had some hard landings.
Still intact.
I do believe Larry has a better solution and Ernie might want to change his design.
My thought was that the Rotax resonance might be a factor?! (As Larry already knows)
Hope to get a list compiled of Dom's with this problem for a comparison.
Mine has an EA-81 Subaru.
 
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