Today's Message Index:
----------------------
1. 03:12 AM - Re: Sprag clutch circlip (Duncan McFadyean)
2. 06:26 AM - My 912ULS (MR PAUL MITCHELL)
3. 07:59 AM - Re: My 912ULS (BOB MCMILLIN)
4. 08:36 AM - Re: My 912ULS (MR PAUL MITCHELL)
5. 09:01 AM - Re: My 912ULS (Duncan McFadyean)
6. 10:30 AM - Re: My 912ULS (MR PAUL MITCHELL)
7. 07:07 PM - Re Sprag Clutch (gtblu)
Message 1
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| Subject: | Re: Sprag clutch circlip |
--> RotaxEngines-List message posted by: "Duncan McFadyean" <ami@mcfadyean.freeserve.co.uk>
Can't answer your question, but would ask for more details about your
experience.
Had the starter sprag been replaced?
Had you been experiencing starting problems?
Duncan McF.
----- Original Message -----
Sent: Saturday, July 01, 2006 11:11 PM
> --> RotaxEngines-List message posted by: "gtblu" <gtbjbell@gmail.com>
>
>
> Hi Listers
>
> I have just had a 912 uls send a cprag clutch circlip through the engine.
> Has anyone experienced this before/
>
> Regards
> Gtblu
>
>
>
Message 2
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I have a 912ULS that has now run 20 hours, It is very harsh , not
exactly a vibration but not smooth. If I do a ignition cut on one side
at 2000rpm I get a smooth drop in revs of 60 to 80. If I cut the other
side I get about 100 but with a real harshness not quite a misfire but
the engine really runs rough. When back on both ignitions this roughness
is evident all through the rev range. I did a compression test today
with one at 158psi, one at 165psi and the other two at 185. Surely they
should be more equal than that after 20 hours running.
Tried all the obvious thing like plugs swapping but not found a cure.
Plug colour seems ok with the front pair slightly darker than the back.
It is at present spoiling my flying.
Any suggestions.
Paul Mitchell
Message 3
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have carbs bin synchronized ? check ground conection 's at coils.
----- Original Message -----
From: MR PAUL MITCHELL
To: rotaxengines-list@matronics.com
Sent: Sunday, July 02, 2006 9:24 AM
Subject: RotaxEngines-List: My 912ULS
I have a 912ULS that has now run 20 hours, It is very harsh , not
exactly a vibration but not smooth. If I do a ignition cut on one side
at 2000rpm I get a smooth drop in revs of 60 to 80. If I cut the other
side I get about 100 but with a real harshness not quite a misfire but
the engine really runs rough. When back on both ignitions this roughness
is evident all through the rev range. I did a compression test today
with one at 158psi, one at 165psi and the other two at 185. Surely they
should be more equal than that after 20 hours running.
Tried all the obvious thing like plugs swapping but not found a cure.
Plug colour seems ok with the front pair slightly darker than the back.
It is at present spoiling my flying.
Any suggestions.
Paul Mitchell
Message 4
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Carbs done, engine will come down to a very smooth 1200 . All electrical
connections checked so many times I dream about it.
Paul
----- Original Message -----
From: BOB MCMILLIN
To: rotaxengines-list@matronics.com
Sent: Sunday, July 02, 2006 3:58 PM
Subject: Re: RotaxEngines-List: My 912ULS
have carbs bin synchronized ? check ground conection 's at coils.
----- Original Message -----
From: MR PAUL MITCHELL
To: rotaxengines-list@matronics.com
Sent: Sunday, July 02, 2006 9:24 AM
Subject: RotaxEngines-List: My 912ULS
I have a 912ULS that has now run 20 hours, It is very harsh , not
exactly a vibration but not smooth. If I do a ignition cut on one side
at 2000rpm I get a smooth drop in revs of 60 to 80. If I cut the other
side I get about 100 but with a real harshness not quite a misfire but
the engine really runs rough. When back on both ignitions this roughness
is evident all through the rev range. I did a compression test today
with one at 158psi, one at 165psi and the other two at 185. Surely they
should be more equal than that after 20 hours running.
Tried all the obvious thing like plugs swapping but not found a
cure. Plug colour seems ok with the front pair slightly darker than the
back. It is at present spoiling my flying.
Any suggestions.
Paul Mitchell
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No virus found in this incoming message.
30-Jun-06
Message 5
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At 20 hours the engine won't be run-in. So I would reserve judgement.
On the other hand, new engines in new 'planes tend to get abused in the
first few hours before cooling matters are sorted and at a time when the
engine runs abnormally hot anyway.
Duncan McF.
----- Original Message -----
From: MR PAUL MITCHELL
To: rotaxengines-list@matronics.com
Sent: Sunday, July 02, 2006 2:24 PM
Subject: RotaxEngines-List: My 912ULS
I have a 912ULS that has now run 20 hours, It is very harsh , not
exactly a vibration but not smooth. If I do a ignition cut on one side
at 2000rpm I get a smooth drop in revs of 60 to 80. If I cut the other
side I get about 100 but with a real harshness not quite a misfire but
the engine really runs rough. When back on both ignitions this roughness
is evident all through the rev range. I did a compression test today
with one at 158psi, one at 165psi and the other two at 185. Surely they
should be more equal than that after 20 hours running.
Tried all the obvious thing like plugs swapping but not found a cure.
Plug colour seems ok with the front pair slightly darker than the back.
It is at present spoiling my flying.
Any suggestions.
Paul Mitchell
Message 6
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Duncan,
Do not think it is heat, it tends to run cool, 150 oil and about the
same CHT,
Paul
----- Original Message -----
From: Duncan McFadyean
To: rotaxengines-list@matronics.com
Sent: Sunday, July 02, 2006 5:00 PM
Subject: Re: RotaxEngines-List: My 912ULS
At 20 hours the engine won't be run-in. So I would reserve judgement.
On the other hand, new engines in new 'planes tend to get abused in
the first few hours before cooling matters are sorted and at a time when
the engine runs abnormally hot anyway.
Duncan McF.
----- Original Message -----
From: MR PAUL MITCHELL
To: rotaxengines-list@matronics.com
Sent: Sunday, July 02, 2006 2:24 PM
Subject: RotaxEngines-List: My 912ULS
I have a 912ULS that has now run 20 hours, It is very harsh , not
exactly a vibration but not smooth. If I do a ignition cut on one side
at 2000rpm I get a smooth drop in revs of 60 to 80. If I cut the other
side I get about 100 but with a real harshness not quite a misfire but
the engine really runs rough. When back on both ignitions this roughness
is evident all through the rev range. I did a compression test today
with one at 158psi, one at 165psi and the other two at 185. Surely they
should be more equal than that after 20 hours running.
Tried all the obvious thing like plugs swapping but not found a
cure. Plug colour seems ok with the front pair slightly darker than the
back. It is at present spoiling my flying.
Any suggestions.
Paul Mitchell
-------------------------------------------------------------------------
-----
No virus found in this incoming message.
30-Jun-06
Message 7
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Thanks Duncan for reply.
Problem started about twenty hours ago with an increasing vibration winding
back to 5000 revs down to 4000. We are talking a vibration that would travel
up the back of the seat and down through my legs. But only at those revs. It
was becoming worse so first step ( after checking prop balance and replacing
the engine mounts) was dismantling gearbox. Found one of the disk spring
(part no 2 in Heavy Maintenance Manual Page 95 fig 146)) had been installed
the wrong way. That has been so for about 400 hours. There was also a lot of
metal bits in the oil tank (912 uls). We suspected that this was a washer.
Reinstalled the gearbox and the vibration was dramatically reduced, but
still there. I suspected paranoia or perhaps that the gearbox problem had
been amplifying a vibration somewhere else!
15 hours down the track and without warning engine would not start.
Symptoms seemed to be as soon as there was a kick in the cylinders of the
slightest nature the starter would let go, allowing the engine to Kick
Back. The only way I could get it started was to reduce the choke to nil,
and advance throttle to about half way. Totally contrary to how I have been
starting it which was as recommended ie full choke throttle just cracked.
Hooking up another battery made no difference.
Scanning Matronics site struck on sprag clutch problems, which seemed
logical on research. The clutch was letting go on the slightest kick which
was just before tdc allowing the engine to kick back in a very unpleasant
way. By using half throttle and no choke the engine wasnt firing so readily
allowing the revs to build up a little and then starting.
I removed the engine and sent it to dealer in Australia and they found the
circlip on the sprag clutch has come off and been broken into pieces.
There is a directive for the circlip to be replaced at 1200 hours but I
suspect this could be an issue before this in some circumstances.
What I dont know is whether the springs in the gearbox being incorrectly
fitted are a primary cause or whether they are unrelated.
As far as I can gather the springs would mean that the amount of travel
would be reduced when the dog gears start to engage. The correct tension was
there but there is no way to check the travel? I cant logically see how
that may affect the sprag clutch except to perhaps kick back a little more
violently because the tension on the dog clutch would build up fairly
quickly with less travel.
So now we go looking for more bits of circlip and hopefully finding the
source of vibration.
Expensive!
Any comments greatly appreciated
Regards
Geoff Bell
Slepcev Storch
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