Today's Message Index:
----------------------
1. 02:42 AM - 582 oil line questions (Dave G)
2. 03:19 AM - 912 uls exhaust gas analysis (ndibiase)
3. 05:36 AM - Re: 912 uls exhaust gas analysis (FLYaDIVE)
4. 05:49 AM - Re: Re: Prop Strike crank damage (Catz631@aol.com)
5. 06:55 AM - Re: 912 uls exhaust gas analysis (Robert Borger)
6. 11:05 AM - Re: 912 uls exhaust gas analysis (rampil)
7. 02:02 PM - Re: 912 uls exhaust gas analysis (Roger Lee)
8. 03:06 PM - Re: Re: Prop Strike crank damage (bjones@dmv.com)
9. 03:43 PM - Re: 912 uls exhaust gas analysis (ndibiase)
10. 08:53 PM - Re: 912 uls exhaust gas analysis (Roger Lee)
Message 1
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Subject: | 582 oil line questions |
During maintenance I examined the oil supply line for my 582 and found
it needs replacement. It has become more prone to kinking over time and
I wish to replace it. The original builder used that "blue" tubing and I
could use that but I am curious what others use.
On the plus side the tubing does not appear to harden with age carrying
oil as I have seen with fuel.
Dave Goddard
KF IV 1050 / 582 / Warp
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Subject: | 912 uls exhaust gas analysis |
For diagnostic reasons after an over speed of unknown entity on my Savannah LSA
plane (consequence : big power loss -500 rpm with perfect carbs , push rods and
compression and leak down tests ok. Growing oil consumption, little misfiring)
i had the suggestion to do an exhaust gas analysis on my rotax 912 uls (100
hrs from new).
Infact after a boroscope analysis (with a very cheap but low res instrument) there
is evidence of some partial burned oil in the combustion chambers (little
spots dark orange caramel like appareance).
Leakage can be suspected from valve stem guides.
Someone has done an exhaust gas analysis on rotax 912 uls ?
Is there experience on witch are the normal range value of Co, Co2 , HC ?
If there is an oil leakage is it shown in altered HC reading values ?
Thanks in advance , i am not an expert and i am very far from nearest rotax service
center.
Nicola di Biase
Read this topic online here:
http://forums.matronics.com/viewtopic.php?p=317834#317834
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Subject: | Re: 912 uls exhaust gas analysis |
Nicola:
I think someone is pulling your leg... Exhaust Gas Analyzation!!!
Just look at your spark plugs. They should be DRY - GRAYISH in color,
sometimes with a brownish tinge and evenly eroding. Eroding, should be ZERO
in 100 Hours.
Check the internet - Look for a CHAMPION SPARK PLUG INSPECTION CHART. It
will give you spark plug color Vs cause.
What color is your engine oil?
When was the last time you changed the oil?
Double Check the compression readings. Sure reads like you have a bad ring
or two.
Look at the exhaust pipe... Is is heavy with BLACK SOOT? It should be light
gray to dark gray or maybe with a slight brownish tinge. It should also
feel dry.
Do you see any oil leaks around the engine? Is there oil spray under the
cowl?
Check your radiator - Any oil in the water?
Barry
On Tue, Nov 2, 2010 at 6:16 AM, ndibiase <ndibiase2@alice.it> wrote:
>
> For diagnostic reasons after an over speed of unknown entity on my Savannah
> LSA plane (consequence : big power loss -500 rpm with perfect carbs , push
> rods and compression and leak down tests ok. Growing oil consumption, little
> misfiring) i had the suggestion to do an exhaust gas analysis on my rotax
> 912 uls (100 hrs from new).
>
> Infact after a boroscope analysis (with a very cheap but low res
> instrument) there is evidence of some partial burned oil in the combustion
> chambers (little spots dark orange caramel like appareance).
>
> Leakage can be suspected from valve stem guides.
>
> Someone has done an exhaust gas analysis on rotax 912 uls ?
>
> Is there experience on witch are the normal range value of Co, Co2 , HC ?
> If there is an oil leakage is it shown in altered HC reading values ?
>
> Thanks in advance , i am not an expert and i am very far from nearest rotax
> service center.
>
> Nicola di Biase
>
>
> Read this topic online here:
>
> http://forums.matronics.com/viewtopic.php?p=317834#317834
>
>
--
Barry
"Chop'd Liver"
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Subject: | Re: Prop Strike crank damage |
Dick, Speaking of that English language bugaboo, did you mike the crank,
i.e. check it's size with a micrometer, or indicate the crank, i.e. place a
sensitive (resolution of .0001" or .005mm) dial indicator on the nose of the
crank and check for runout as the crank is rotated? The latter is what is
required after a prop strike, while the former is a nice to do but doesn't
really tell you much unless there is evidence that the taper on the crank
nose or the mating surface of the drive gear is damaged.
See the Line Maintenance Manual, <<
Rick
I just returned from vacation and was too pooped to talk let alone type!
Too many errors.
No,a dial indicator was applied to the crank to determine the runout and
it was fine, gearbox check will be next.(will use the manual as a guide)
Dick Maddux
912UL
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Subject: | Re: 912 uls exhaust gas analysis |
Nicola,
One of the biggest issues with an overspeed in a 9xx is a piston contacting a valve.
This can result in damage to the piston, a bent valve stem, damaged valve
guide or damage to other parts of the valve train. The engine probably needs
to be checked by a ROTAX repair shop to ensure everything in the valve train
is OK. They will also have a better knowledge of what other things may go wrong
as a result of an overspeed.
Good luck!
Bob Borger
Europa Kit #A221 N914XL, XS Tri-Gear, Intercooled 914, Airmaster C/S Prop
http://www.europaowners.org/forums/gallery2.php?g2_itemId=60232
http://www.biplaneforumgallery.com/index.php?cat=10046
Europa Flying!
3705 Lynchburg Dr.
Corinth, TX 76208
Home: 940-497-2123
Cel: 817-992-1117
On Nov 2, 2010, at 5:16, ndibiase wrote:
>
> For diagnostic reasons after an over speed of unknown entity on my Savannah LSA
plane (consequence : big power loss -500 rpm with perfect carbs , push rods
and compression and leak down tests ok. Growing oil consumption, little misfiring)
i had the suggestion to do an exhaust gas analysis on my rotax 912 uls (100
hrs from new).
>
> Infact after a boroscope analysis (with a very cheap but low res instrument)
there is evidence of some partial burned oil in the combustion chambers (little
spots dark orange caramel like appareance).
>
> Leakage can be suspected from valve stem guides.
>
> Someone has done an exhaust gas analysis on rotax 912 uls ?
>
> Is there experience on witch are the normal range value of Co, Co2 , HC ?
> If there is an oil leakage is it shown in altered HC reading values ?
>
> Thanks in advance , i am not an expert and i am very far from nearest rotax service
center.
>
> Nicola di Biase
Message 6
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Subject: | Re: 912 uls exhaust gas analysis |
I agree with Bob.
The engine manuals are free for the taking on the web and tell
you exactly what to do in case of an engine overspeed or other
issue.
If you are working in isolation, read the books and don't bother
asking advise from people who are not very familiar with the Rotax.
It is not like other aircraft engines in many ways.
Gas analysis is not a routine procedure, is not recommended by
Rotax, and would not be the best way to diagnose bent lifters and
bad, floated valves from an overspeed.
--------
Ira N224XS
Read this topic online here:
http://forums.matronics.com/viewtopic.php?p=317880#317880
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Subject: | Re: 912 uls exhaust gas analysis |
Hi Nicola,
How bad was the over speed? With prop or without? How long? Do all of the engine
temps and pressures look good and do you have all the read outs? (EGT, CHT
ect...)
You said now that oil is constantly used? What does the inside of the exhaust pipe
look like? (Oily, dry, black soot, gray soot ect...)
There is a procedure in the maint. manual for the over speed check, but these guys
are right that a Rotax shop should do the check.
--------
Roger Lee
Tucson, Az.
Light Sport Repairman - Maintenance Rated
Rotax Repair Center
Home 520-574-1080 TRY HOME FIRST
Cell 520349-7056
Read this topic online here:
http://forums.matronics.com/viewtopic.php?p=317894#317894
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Subject: | Re: Prop Strike crank damage |
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Message 9
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Subject: | Re: 912 uls exhaust gas analysis |
Roger Lee wrote:
> Hi Nicola,
>
> How bad was the over speed? With prop or without? How long? Do all of the engine
temps and pressures look good and do you have all the read outs? (EGT, CHT
ect...)
> You said now that oil is constantly used? What does the inside of the exhaust
pipe look like? (Oily, dry, black soot, gray soot ect...)
> There is a procedure in the maint. manual for the over speed check, but these
guys are right that a Rotax shop should do the check.
Over speed was of unknown entity , perhaps > 6200 rpm (i was forced to do a sudden
collision avoidance maneuver in the traffic circuit with full throttle, high
airplane speed and bad -minimum pitch- variable propeller setting) but it last
for only 2-3 seconds.
After that ,there was huge power loss (550 rpm) , CHT normal, EGT with no abnormal
sign (max 30 Celsius spread between cylinder couple and 90 between front and
rear). Very little misfiring at low load/rpm. Oil consumption has gone from
almost negligible to 250 gr. in 2-3 hour.
Leak down test and compression test perfect. carbs and leverages are ok.
spark plug seems ok.
Boroscope analysis (with a very cheap and low res instrument) showed evidence
of some partial burned oil in the combustion chambers (little spots dark orange
caramel like appearance) but i am not an expert and this is my first time of
using this kind of instrument in an engine.
There was also a very subtle sign. Oil recovery procedure (the "gurgle") takes
much more propeller turns than before. I am not a mechanic but, in my humble opinion,
this can be sign of valve stem guide problems (crankcase pressure escape
from the valve guides- heads in 912 are pressurized ). Is it a reasonable hypothesis
?
There is some black soot in the exhaust.
i know that in case over speed > 6200 rpm Rotax maint. manual states "the whole
engine must be inspected......and i will contact nearest rotax heavy maintenance
center. But i'd like to do a logical analysis before to open the engine.
My summary :
If is it a valve train problem it is strange that leak down and compression tests
are perfect.
if is it a crankshaft problem it seems very strange to have not a lot of engine
vibrations. i'd like to know how common and what are the usual signs of crankshaft
problems in 912 ULS?.
thanks
Nicola di Biase
Read this topic online here:
http://forums.matronics.com/viewtopic.php?p=317910#317910
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Subject: | Re: 912 uls exhaust gas analysis |
I sent Nicola's comments in for a second opinion and here is what was said. This
come from way up the food chain and should be considered very good information
to follow.
Roger
First, what was the differential pressure test result per cylinder, to just say
its ok is not good enough in this case. While the book says you can accept
25% loss I would not personally, anything over 10 would send an alarm bell ringing
for me.
Indeed, if the RPM was high enough the only way you would do anything is if you
kissed a valve and perhaps bent a push rod or two. If the report is correct
higher oil consumption might indicate damage to the oil ring(s) and that might
have happened in the case of cracking the piston ring lands if the piston hit
the head(s)
For sure since he reports performance loss treat it as requiring more in-depth
inspection. Remove the heads, check all the push rods and pistons. With the
heads off you will know right away if you have a sticking valve. If you have
any bent push rods pull all the valves and check for bent valve faces.
On the good side, if no valves hit the pistons it is extremely unlikely to have
caused any crankshaft problems, so this should be fine.
The report that it is harder to get it to gurgle can be a sign of perhaps damaged
rings, or leaking valves, both of which would cause the engine case pressures
to be slightly lower and affect the case pressure.
My recommendation, bring it to someone who can do a good evaluation of the top
end.
--------
Roger Lee
Tucson, Az.
Light Sport Repairman - Maintenance Rated
Rotax Repair Center
Home 520-574-1080 TRY HOME FIRST
Cell 520349-7056
Read this topic online here:
http://forums.matronics.com/viewtopic.php?p=317937#317937
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