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undoctor
Joined: 21 Oct 2008
Posts: 212
Location: Bethelhem, PA
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 Posted: Thu Oct 17, 2013 11:30 am Post subject: 447 problem and expense |
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Hello Rotax wizards,
I'm searching for answers while I still live and breathe and have some
money left. I'll try to give all the pertinent info to see if someone
on the list can come up with an answer no small engine mechanic I spoke
to in my area was able to diagnose.
I have a FireFly which was damaged when Hurricane Sandy blew through.
Last winter I removed the wings and took them to a builder for some
rather minor repairs. I didn't get them back until well into the flying
season, but my 447 was safely fogged before shutdown.
A couple of months ago when I got the wings back and mounted I set the
FF up and started the engine. It seemed to run pretty good after
setting for so long, but the front cylinder wasn't warming up at the
same rate as the rear. After both cylinders were within operating temps
I revved it a while, then tied the FF off and gave it full throttle to
check max static RPMs. I was looking for the 6200 I had before the
Hurricane, but could only get 5800, so I shut it down and put the carb
at defualt settings. I started it up again and ran it up to max, still
5800, and left it work for less than two minutes, hoping if a ring was
stuck, etc. it would loosen up and run right.
At WOT the engine shut down and pulling the exhaust manifold revealed a
scored front piston. Since no one could give me a definitive diagnosis
of why it seized and since the piston had to be replaced, etc. I bought
two 1 over piston sets, the gasket packet for an overhaul, sent the jugs
to be bored to accept the 1 voer pistions, and had a good motorcycle
mechanic put it all together (one who builds motorcycles).
Put the engine back on, along with a new EGT thermocouple to replace one
I had to butcher to get out of the manifold, and started it up. It
started easily but idled rough needing the enricher to be halfway out
and it wouldn't take any throttle, so I removed the carb and took it to
the mechanic who cleaned it and replaced the needle and jets.
Put the carb back on and started it up. It now idled smoothly and took
fuel beautifully but the one EGT didn't begin to rise for quite a few
seconds. It did, however come up to the other cylinder temp and the
CHTs were pretty similar in their rise, so I thought with new bores,
pistons, carb, it must be the response of the new EGT thermocouple. I
ran it up and down, up and down, then tied it off to check max static.
It got up to over 6100, so I was satisfied that a new tight engine may
have to break in a tad before it would reach the 6200 it had before. I
taxied down to the end of the runway, which is downhill, turned around
and taxied back up the hill where I could give it quite a bit of
throttle without taking off. It sounded smooth and beautiful, so I
taxied all the way to the top of the runway to give myself all the
runway I could since I had to analyze any effect of the repaired wings
before going out.
Ran it up against the brakes almost to tail-up, released the brakes
started my roll, giving it full throttle as soon as I had horizontal
stab authority. It took off beautifully, the handling was accurate and
neat so I pulled the stick back and said goodbye to the world for the
first time in almost a year.
It was a euphoric few minutes, the engine sounded fantastic, so at about
1000' AGL I throttled back and leveled off. Within seconds it got very
quiet and knowing I couldn't do a 180 and land back at the strip I
looked for a place to set down. Nice field next to a road so I set my
glide path for it. I thought it was a soybean field, which it was, and
that soybeans grew low, which they don't and quickly learned that
landing in a soybean field in October is only slightly better than
landing in a forest.
A man who saw me going in took me back to the airstrip where I got my
cycle and rode back to the FF to remove the radio, GPS, etc. My
analysis was, since the engine and carb were virtually new, it must be
electrical or fuel starvation. I flipped the ignition switch, pulled
the starter and it fired up on the first pull. Advanced the throttle
and it wanted to fly.
Next day I returned and disassembled the plane and removed the engine,
wings and all the little stuff, walked them out the path through the 2'
high tangle of soybeans to my pickup and returned them to my hangar.
Last Thur. a couple of friends went with me and we carried the plane out
of the field. I brought the engine, chute, etc., home and a few days
ago I removed the exhaust manifold to make sure the pistons were OK.
They weren't; the front piston had seized again. Ever see a grown man
cry????
Before I go any further with repairing the engine or the FF I want to be
pretty sure of what I'm looking at, so if any of you experienced Rotax
wrenchers have an educated theory, I'd just love to hear it. Any and
all thoughts are welcome and will add to the data bank.
Thanks,
Dave Kulp
Bethlehem, PA
FireFly 11DMK
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rickofudall
Joined: 19 Sep 2009
Posts: 1392
Location: Udall, KS, USA
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| Posted: Thu Oct 17, 2013 6:45 pm Post subject: 447 problem and expense |
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|
Dave, I am very sorry to hear about your troubles and that the Flag Fly is down again. It sounds like you have an air leak on the front cylinder. You might have a front seal that's gone bad, a leak in the gasket at the intake manifold front cylinder, or a leak at the exhaust manifold. Does your mechanic know how to do a crankcase pressure test? You might have to get a little fancier than and include both manifolds, but I think that might be where to start. Let me tell you a story. I have a Shovelhead Harley. When I first got it I had an S & S Super B carb that was worn out so I got the latest and greatest, the S & S Super E. The engine ran great, except every time I looked at the plugs I had a white front plug and a dark brown rear plug. I must have changed O rings and intake clamps a dozen times. I tried rubber band seals instead. I even tried a high bred system that used both O rings AND rubber bands. I was really stumped and then a buddy of mine suggested I try an SU carb. I did and the problem went away. I sold the S & S carb to a buddy. He put it on and within a week he called to say he had a dark front plug and a white rear plug. I was just insane and drove right over to his house. We looked at the carb and intake manifold, had a couple of shots of good single malt scotch, and then I had an idea. I asked Charlie for his dental mirror and went looking for the mark on the intake manifold that tells you it's right side up (even though it's symmetrical). Sure enough he had put the intake with the mark on the bottom, I always had it on top. All that time I'd been fighting the wrong battle. The intake manifold had a small porosity on one leg, hence the color of the plugs changed from Charlie's engine to mine, when the porosity moved from front to back.
My point is that the problem with your engine may not lie in an obvious direction. Don't give up.
Rick Girard
On Thu, Oct 17, 2013 at 2:29 PM, David Kulp <undoctor(at)ptd.net (undoctor(at)ptd.net)> wrote:
| Quote: | --> RotaxEngines-List message posted by: David Kulp <undoctor(at)ptd.net (undoctor(at)ptd.net)>
Hello Rotax wizards,
I'm searching for answers while I still live and breathe and have some money left. I'll try to give all the pertinent info to see if someone on the list can come up with an answer no small engine mechanic I spoke to in my area was able to diagnose.
I have a FireFly which was damaged when Hurricane Sandy blew through. Last winter I removed the wings and took them to a builder for some rather minor repairs. I didn't get them back until well into the flying season, but my 447 was safely fogged before shutdown.
A couple of months ago when I got the wings back and mounted I set the FF up and started the engine. It seemed to run pretty good after setting for so long, but the front cylinder wasn't warming up at the same rate as the rear. After both cylinders were within operating temps I revved it a while, then tied the FF off and gave it full throttle to check max static RPMs. I was looking for the 6200 I had before the Hurricane, but could only get 5800, so I shut it down and put the carb at defualt settings. I started it up again and ran it up to max, still 5800, and left it work for less than two minutes, hoping if a ring was stuck, etc. it would loosen up and run right.
At WOT the engine shut down and pulling the exhaust manifold revealed a scored front piston. Since no one could give me a definitive diagnosis of why it seized and since the piston had to be replaced, etc. I bought two 1 over piston sets, the gasket packet for an overhaul, sent the jugs to be bored to accept the 1 voer pistions, and had a good motorcycle mechanic put it all together (one who builds motorcycles).
Put the engine back on, along with a new EGT thermocouple to replace one I had to butcher to get out of the manifold, and started it up. It started easily but idled rough needing the enricher to be halfway out and it wouldn't take any throttle, so I removed the carb and took it to the mechanic who cleaned it and replaced the needle and jets.
Put the carb back on and started it up. It now idled smoothly and took fuel beautifully but the one EGT didn't begin to rise for quite a few seconds. It did, however come up to the other cylinder temp and the CHTs were pretty similar in their rise, so I thought with new bores, pistons, carb, it must be the response of the new EGT thermocouple. I ran it up and down, up and down, then tied it off to check max static. It got up to over 6100, so I was satisfied that a new tight engine may have to break in a tad before it would reach the 6200 it had before. I taxied down to the end of the runway, which is downhill, turned around and taxied back up the hill where I could give it quite a bit of throttle without taking off. It sounded smooth and beautiful, so I taxied all the way to the top of the runway to give myself all the runway I could since I had to analyze any effect of the repaired wings before going out.
Ran it up against the brakes almost to tail-up, released the brakes started my roll, giving it full throttle as soon as I had horizontal stab authority. It took off beautifully, the handling was accurate and neat so I pulled the stick back and said goodbye to the world for the first time in almost a year.
It was a euphoric few minutes, the engine sounded fantastic, so at about 1000' AGL I throttled back and leveled off. Within seconds it got very quiet and knowing I couldn't do a 180 and land back at the strip I looked for a place to set down. Nice field next to a road so I set my glide path for it. I thought it was a soybean field, which it was, and that soybeans grew low, which they don't and quickly learned that landing in a soybean field in October is only slightly better than landing in a forest.
A man who saw me going in took me back to the airstrip where I got my cycle and rode back to the FF to remove the radio, GPS, etc. My analysis was, since the engine and carb were virtually new, it must be electrical or fuel starvation. I flipped the ignition switch, pulled the starter and it fired up on the first pull. Advanced the throttle and it wanted to fly.
Next day I returned and disassembled the plane and removed the engine, wings and all the little stuff, walked them out the path through the 2' high tangle of soybeans to my pickup and returned them to my hangar. Last Thur. a couple of friends went with me and we carried the plane out of the field. I brought the engine, chute, etc., home and a few days ago I removed the exhaust manifold to make sure the pistons were OK. They weren't; the front piston had seized again. Ever see a grown man cry????
Before I go any further with repairing the engine or the FF I want to be pretty sure of what I'm looking at, so if any of you experienced Rotax wrenchers have an educated theory, I'd just love to hear it. Any and all thoughts are welcome and will add to the data bank.
Thanks,
Dave Kulp
Bethlehem, PA
FireFly 11DMK
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It isn't necessary to have relatives in Kansas City in order to be unhappy.
- Groucho Marx
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