Today's Message Index:
----------------------
1. 02:56 AM - Re: Kick back on starting (Gtblu)
2. 03:17 AM - Engine Vibration (Gtblu)
3. 03:56 AM - Re: Kick back on starting (Matt Tucciarone)
4. 07:12 AM - Rotax 912UL for sale (Tim Perkins)
5. 07:41 AM - Re: Engine Vibration (Roger Lee)
6. 04:12 PM - Re: Engine Vibration (Gtblu)
7. 04:30 PM - Re: Engine Vibration (Roger Lee)
8. 06:03 PM - Re: Engine Vibration (Gtblu)
9. 07:00 PM - Re: Re: Kick back on starting (Craig Payne)
Message 1
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| Subject: | Re: Kick back on starting |
Hi Paul, I had the same symptoms at about the same hours on a 912 uls which proved
to be sprag clutch. In this case the circlip holding the sprag clutch together
came off and went through the engine. We didn't ascertain whether the circlip
came off because the clutch had worn out and the violent kick backs caused
the circlip to break or the other way round. The damage was considerable with
chunks of circlip ending up in the oil tank and damage to water pump cogs and
starter cogs.
If it is the sprag clutch then battery or starter won't solve the issue I feel.
You could check the battery by jump starting from a heavy duty truck or car battery.
I did replace the starter with a Rotax HD starter which had been faultless ever
since and starts first kick everytime. It is a bit longer that the old starter
motor.
You could also check for metal in the oil tank.
The kick backs are violent and damaging, so the sooner the better for resolution.
I think I persisted too long trying to get it started rather than accepting
it was the sprag clutch.
Good luck
regards
GtBlu
Read this topic online here:
http://forums.matronics.com/viewtopic.php?p=187702#187702
Message 2
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| Subject: | Engine Vibration |
Hi all,
Just wanted to close issue of an 912 uls engine that was vibrating/resonating at
5000 revs and above. I think I have finally resolved the issue by exchanging
props. Vibration disappeared instantly prompting me to really focus on the original
prop. It seems the bolts attaching prop to engine were fractionally too
long so that torquing them up wasn't tightening them properly. We are talking
microns here but enough to allow a resonance on certain days given certain conditions.
A little wear on the washers reduced the tension causing the sudden
change. Temperature may have been expanding or contracting various bits such as
hub and bolts to make more or less tension as well. A little wear on the hub
and "smoke" on the back of the hub suggested that things were moving.
Thanks to all for ideas and thoughts, and especially Roger Lee and "Buffalo Thom"
for great advice and patience.
It's been fascinating trying a few props as they are all so different in their
nature prompting me to try more. I'd like to hear other users experience on this
ie what revs do they vibrate in, etc.
The wooden 2 blade prop creates a kind of rumble in the air and feels softer on
the engine. Its swish out of time with the engine was quite disconcerting to
start with. It has a vibration/resonance zone around 4000 revs
The old three blade vibrated at around 4800, but man does it rip off the strip!
Fascinating
Thanks again
regards
Geoff Bell
Read this topic online here:
http://forums.matronics.com/viewtopic.php?p=187704#187704
Message 3
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| Subject: | Kick back on starting |
Paul,
I also had to replace my sprag clutch. Lockwood used to rent the wrench to
do the job. I sent my 912s to them and it cost about a grand when it was all
over.
The kickbacks did some damage to my ignition wires and it will fry your carb
sockets. I now take no chances. I have the Odyssey battery with 925 cranking
amps, and the rotax high torque starter.
Matt
_____
From: owner-rotaxengines-list-server@matronics.com
[mailto:owner-rotaxengines-list-server@matronics.com] On Behalf Of Paul
McAllister
Sent: Thursday, June 12, 2008 8:17 PM
Subject: RotaxEngines-List: Kick back on starting
Hi all,
My 914 has just started the evil habit of kicking back when trying to start
it cold. I called Lockwood Aviation and they told me that the sprag clutch
probably needs changing, my engine has nearly 800 hours on it. Anyhow, I
called the mechanic at a nearby airport who works on Rotax's and he came up
with some different advice.
The first one is easy, since the battery is 3 years old maybe its time to
swap it. Its a 18 ah Odyssey and although it seems in good shape maybe its
time.
The next advice was if the kick back stuff has just started then is would be
easier to fit a starter engine from a 912S than to go to all of the grief of
pulling the engine, removing the ignition housing, replacing the clutch and
so forth.
So, my question to the forum, I seem to recall the Skytec now offer a 912S
starter. Has anyone had any experience with this. Would they happen to be
the OEM supplier to Rotax.
Any thoughts or suggestions would be appreciated.
Thanks, Paul
BTW, the other thing I am looking into is a product called SoftStart sold by
the Rotax agent in the UK. This unit apparently works by starting on one
mag and it retards the timing just for starting. Once the engine fires up
it flips the timing to be correct and you turn on the second mag. I have
ordered one so I will keep you all posted.
Message 4
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| Subject: | Rotax 912UL for sale |
I have a Rotax 912UL (80hp) with ~250 hrs on it. My instructor had a
landing incident resulting in a minor prop strike in June 2006. The plastic
insert of the GSC wood prop was knocked out, but the engine kept running
until I shut it down. Although several sources said it was unlikely there
was any damage, I had the engine torn down by a certified Rotax shop to
inspect the gearbox (no problems) and flange runout (in spec). Had the Bing
carbs serviced at the same time. It has been reinstalled on the plane and
run briefly since the incident and seems to operate fine. Asking $6,500
(firm) for engine, or $7,000 for engine/FWF/engine instruments (Zenith
601HD/VDO).
Buyer will need to arrange pickup in Vermont.
Email me OFF-LIST at vtootm@accessvt.com or call me at 802-434-4738 (leave a
message). Don't reply to the list as I only subscribe to the digest version
and only read it occasionally, and to avoid list clutter.
Do not archive
Tim Perkins
Message 5
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| Subject: | Re: Engine Vibration |
Hi Geoff,
Congratulations.
I know chasing a ghost can be frustrating to say the least. Wood props are usually
formed by hand after the roughing out. The prop bolts on a wood prop should
be re torqued every couple of months due to wood's expanding and contracting
properties. This can be a little more pronounced in different parts of the country
(i.e. dry climates v.s. humid climates).
Out of curiosity did you ever balance your old prop and check blade tracking?
I just checked a guys prop that had flown in from N.Y. and traveling around the
country. He complained of very slow rate of climb with his 912ULS in a Flight
Design CT (100' a min). He was only getting
5150-5200rpm WOT straight/level. When I checked the three blade prop one blade
was out from the other two 3/4 degree. I re pitched all of them to achieve 5500rpm.
It was like a whole new engine and he stated that the vibration he had been
feeling for a while was gone.
--------
Roger Lee
Tucson, Az.
Light Sport Repairman - Maintenance Rated
Rotax Service Center
520-574-1080
Read this topic online here:
http://forums.matronics.com/viewtopic.php?p=187738#187738
Message 6
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| Subject: | Re: Engine Vibration |
Hi Roger,
I did check the tracking, and one blade was out. I voiced my concerns to the manufacturer,
and they said that they were within tolerances. I also voiced concern
that the pitch varied down the blade on one blade compared to the other two.
That is to say that if I pitched the blades at say 200 mm from the tip, they
were not equal on the tip by half a degree. Manufacturer also said that was
within tolerances, but did say send them back for balance check. I inspected the
prop very carefully with magnifying glasses and found some damage right up
near the hub on two blades (not the one that was different?). The blade root
has come in contact with the corner of the radiator before my time.
I have ordered a new prop!
Such a relief.
Thanks Roger
regards
Geoff Bell
Read this topic online here:
http://forums.matronics.com/viewtopic.php?p=187800#187800
Message 7
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| Subject: | Re: Engine Vibration |
Hey Geoff,
Who's prop do you have?
Now you will be able to sleep at nights and fly in the morning and leave to worry
part behind. :D
--------
Roger Lee
Tucson, Az.
Light Sport Repairman - Maintenance Rated
Rotax Service Center
520-574-1080
Read this topic online here:
http://forums.matronics.com/viewtopic.php?p=187806#187806
Message 8
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| Subject: | Re: Engine Vibration |
Hi Roger,
really I'm just very glad it didn't break in flight. It must have been on the cards!
regards
Geoff Bell
Read this topic online here:
http://forums.matronics.com/viewtopic.php?p=187819#187819
Message 9
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| Subject: | Re: Kick back on starting |
I don't know how old your engine is but there is a service instruction from
7/2001 on changing the circlip to a different design:
SI-912-006
SI-914-008
-- Craig
-----Original Message-----
From: owner-rotaxengines-list-server@matronics.com
[mailto:owner-rotaxengines-list-server@matronics.com] On Behalf Of Gtblu
Sent: Friday, June 13, 2008 3:54 AM
Subject: RotaxEngines-List: Re: Kick back on starting
Hi Paul, I had the same symptoms at about the same hours on a 912 uls which
proved to be sprag clutch. In this case the circlip holding the sprag clutch
together came off and went through the engine. We didn't ascertain whether
the circlip came off because the clutch had worn out and the violent kick
backs caused the circlip to break or the other way round. The damage was
considerable with chunks of circlip ending up in the oil tank and damage to
water pump cogs and starter cogs.
If it is the sprag clutch then battery or starter won't solve the issue I
feel.
You could check the battery by jump starting from a heavy duty truck or car
battery.
I did replace the starter with a Rotax HD starter which had been faultless
ever since and starts first kick everytime. It is a bit longer that the old
starter motor.
You could also check for metal in the oil tank.
The kick backs are violent and damaging, so the sooner the better for
resolution. I think I persisted too long trying to get it started rather
than accepting it was the sprag clutch.
Good luck
regards
GtBlu
Read this topic online here:
http://forums.matronics.com/viewtopic.php?p=187702#187702
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