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912S engine vibration

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riddon(at)sent.com
Guest

Posted: Sat Aug 05, 2006 1:45 am Post subject: 912S engine vibration

I am experiencing a slight vibration whilst at cruise speed / rev’s. I have tried a number of things to rectify it including balancing the prop (thanks to Mark Burton), checking the carb mounting rubbers for splits, balancing the carb’s and changing the spark plugs.  All to no avail.  It is not a major vibration and, having got a little paranoid about it, it is maybe mostly in my head now but I am still slightly concerned about it.  Seems to be worst at around 110 knots with the prop at ‘cruise’ setting, i.e. 5000 rpm and a manifold pressure around 23in.   Engine is 912S with an Airmaster prop.   

   

Any idea’s?  

   

Incidentally when checking the carb mounting rubbers I did discover a split starting in one.  It hadn’t gone right through but was significant so I have changed them for the latest mounting rubbers. This has probably been discussed before but If you are not sure whether yours are the latest, look at the jubilee type clip which holds them to the carb.  The latest have a spacer inserted to stop you overtightening them. Another check is the number on the flange.  My old one’s were numbered 267787 and the new one’s 267788  

   

Richard Iddon G-RIXS

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ami(at)mcfadyean.freeserv
Guest

Posted: Sat Aug 05, 2006 2:17 am Post subject: 912S engine vibration

<< I did discover a split starting in0 one>>

  

 Richard,

 Have you always had the airbox fitted?

  It is unusual to find the rubbers splitting0 in the presence of an airbox.

 Can't comment on the vibration, other than to check0 that any LE prop protection is secure.

  

 Rgds.,

 Duncan.

 [quote]   ---

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riddon(at)sent.com
Guest

Posted: Sat Aug 05, 2006 3:13 am Post subject: 912S engine vibration

Duncan.  

   

I always have had the airbox fitted.  It was my local Rotax man who urged me to have a closer look at the rubbers.  He tells me that he has come across splits in the sockets on engines with only a few hours although these are probably on microlights with unsupported carbs. I couldn’t see the crack with the rubbers in place, I had to remove them completely and bend them around to find it.   

   

Cheers.  

   

Richard.   

   

-----Original Message-----

 From: owner-europa-list-server(at)matronics.com [mailto:owner-europa-list-server(at)matronics.com] On Behalf Of Duncan McFadyean

 Sent: 05 August 2006 11:16

 To: europa-list(at)matronics.com

 Subject: Re: 912S engine vibration  

     

<< I did discover a split starting in one>>  

    

   

    

Richard,  

    

Have you always had the airbox fitted?  

    

 It is unusual to find the rubbers splitting in the presence of an airbox.  

    

Can't comment on the vibration, other than to check that any LE prop protection is secure.  

    

   

    

Rgds.,  

    

Duncan.  

  [quote]    

---

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rparigor(at)suffolk.lib.n
Guest

Posted: Sat Aug 05, 2006 11:04 am Post subject: 912S engine vibration

Hello Richard



"I am experiencing a slight vibration whilst at cruise speed / rev's."

"Any idea's?"



Have a look at:

http://www.rotaxservice.com/rotax_tips/rotax_vibration.htm

Have a look at causes of vibration and troubleshooting.



You will need to install Microsoft PowerPoint Viewer, free on that link if

Powerpoint will not open as was the case with my version. You need to

download the ppt, then open the viewer, and open the ppt through the

viewer.



Does operating on 1 igniton then the other change things?



You said you adjusted your carb sync. Did you make absolute certain that

the routing of your cables is not creating lost motion due to flexing of

the cables? How about the bug nuts perhaps being overtightened (bug nuts

are the cylinder in the carb linkage arm that you thread the cable through

and tighten the screw to hold the cable) if the cylinder is not able to

rotate free it can cause carbs to become out of sync, just like the

hysteriousis caused by flexing of cables.



You check careful no cable too close to heat and got damaged?



Did you replace the float pins as per the bulletin? If you think carbs are

perhaps a bit rich, turn off your fuel selector in cruise, when bowls go

low mixture will get leaner, best do it only for an instant, turn off

fuel, if it gets better, pull power and turn on selector, go land and

trouble shoot rich. If it has no change, the split second it begins to get

rough, or if you have a EGT and you see going high, pull power, and turn

on selector. I have no first hand experience with a Europa, but the BD5

used to adjust mixture (leaner) by having a needle valve control flow into

the 3 carbs of a Zenoah! It is possable that if you are good with fiddly

things you could actual restrict flow enough with selector to prolong the

good running to be sure.



Did you check to make absolute sure the prop blades are in good shape,

that they are tracking precise and that the angles are exact? The spinner

is tracking true, tight and no severe cracks?



Did you check to see if your undercarriage mounting frame is cracked>

Inspect motor mounts, tight and the motor mount and mounting ring OK.



Are your both your carb float bowl vents in good shape, no kinks and run

to ambient air?



Fly at vibration speed for a while, land and check plugs for color? Best

to pull power quit engine and deadstick but if not wanting to do that,

lose altitude with power setting left alone and lose altitude with steep

turns, and land and shut down as quick as practicable.



Check very careful your exhaust for cracks, your carbs are not covered in

exhaust grunge by chance, are they?



Let us know resolve.

Ron Parigoris

- The Matronics Europa-List Email Forum -

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rparigor(at)suffolk.lib.n
Guest

Posted: Sat Aug 05, 2006 11:04 am Post subject: 912S engine vibration

Hello Richard



"I am experiencing a slight vibration whilst at cruise speed / rev's."

"Any idea's?"



Have a look at:

http://www.rotaxservice.com/rotax_tips/rotax_vibration.htm

Have a look at causes of vibration and troubleshooting.



You will need to install Microsoft PowerPoint Viewer, free on that link if

Powerpoint will not open as was the case with my version. You need to

download the ppt, then open the viewer, and open the ppt through the

viewer.



Does operating on 1 igniton then the other change things?



You said you adjusted your carb sync. Did you make absolute certain that

the routing of your cables is not creating lost motion due to flexing of

the cables? How about the bug nuts perhaps being overtightened (bug nuts

are the cylinder in the carb linkage arm that you thread the cable through

and tighten the screw to hold the cable) if the cylinder is not able to

rotate free it can cause carbs to become out of sync, just like the

hysteriousis caused by flexing of cables.



You check careful no cable too close to heat and got damaged?



Did you replace the float pins as per the bulletin? If you think carbs are

perhaps a bit rich, turn off your fuel selector in cruise, when bowls go

low mixture will get leaner, best do it only for an instant, turn off

fuel, if it gets better, pull power and turn on selector, go land and

trouble shoot rich. If it has no change, the split second it begins to get

rough, or if you have a EGT and you see going high, pull power, and turn

on selector. I have no first hand experience with a Europa, but the BD5

used to adjust mixture (leaner) by having a needle valve control flow into

the 3 carbs of a Zenoah! It is possable that if you are good with fiddly

things you could actual restrict flow enough with selector to prolong the

good running to be sure.



Did you check to make absolute sure the prop blades are in good shape,

that they are tracking precise and that the angles are exact? The spinner

is tracking true, tight and no severe cracks?



Did you check to see if your undercarriage mounting frame is cracked>

Inspect motor mounts, tight and the motor mount and mounting ring OK.



Are your both your carb float bowl vents in good shape, no kinks and run

to ambient air?



Fly at vibration speed for a while, land and check plugs for color? Best

to pull power quit engine and deadstick but if not wanting to do that,

lose altitude with power setting left alone and lose altitude with steep

turns, and land and shut down as quick as practicable.



Check very careful your exhaust for cracks, your carbs are not covered in

exhaust grunge by chance, are they?



Let us know resolve.

Ron Parigoris

- The Matronics Europa-List Email Forum -

Use the List Feature Navigator to browse the many List utilities available such as the Email Subscriptions page, Archive Search & Download, 7-Day Browse, Chat, FAQ, Photoshare, and much more:

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kpaviat(at)verizon.net
Guest

Posted: Sat Aug 05, 2006 3:53 pm Post subject: 912S engine vibration

Hello Richard!

 I noticed that the replies to your vibration inquiry included everything external. My 912, at about 400 hours started developing a significant vibration that drove me nuts until I sent in the propeller speed reduction assembly in for service. Upon disassembly, I noticed that the primary gear set from the crankshaft to the driving dog was worn. Whatever frequency was associated with that apparently translated to low frequency vibration output to the gearbox and engine. I replaced the gear set in addition to the usual servicing of the gearbox and this made the engine smooth again. An internal problem, not external. I don’t know how many hours you have on your Rotax and if you have serviced the gearbox at the recommended 200 hour intervals but this can make a significant difference and has proven out in other Europas with same complaint. 

 Good Luck and ...

 Happy Skies!

 kp

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riddon(at)sent.com
Guest

Posted: Sun Aug 06, 2006 12:34 am Post subject: 912S engine vibration

Kim,  

   

My engine has done around 300 hours and I wasn’t aware of the need to service the gearbox at 200 hour intervals. All I can find on the Rotax web site is SB-912-033 service bulletin which recommends inspecting the gearbox at 600 hours if using avgas for more than 30% of the time. Can you point me in the direction of the instructions for servicing the gearbox?  

   

Regards,  

   

Richard.   

   

-----Original Message-----

 From: owner-europa-list-server(at)matronics.com [mailto:owner-europa-list-server(at)matronics.com] On Behalf Of Kim Prout

 Sent: 06 August 2006 00:52

 To: europa-list(at)matronics.com

 Subject: Re: 912S engine vibration  

   

Hello Richard!

 I noticed that the replies to your vibration inquiry included everything external. My 912, at about 400 hours started developing a significant vibration that drove me nuts until I sent in the propeller speed reduction assembly in for service. Upon disassembly, I noticed that the primary gear set from the crankshaft to the driving dog was worn. Whatever frequency was associated with that apparently translated to low frequency vibration output to the gearbox and engine. I replaced the gear set in addition to the usual servicing of the gearbox and this made the engine smooth again. An internal problem, not external. I don’t know how many hours you have on your Rotax and if you have serviced the gearbox at the recommended 200 hour intervals but this can make a significant difference and has proven out in other Europas with same complaint. 

 Good Luck and ...

 Happy Skies!

 kp

- The Matronics Europa-List Email Forum -

Use the List Feature Navigator to browse the many List utilities available such as the Email Subscriptions page, Archive Search & Download, 7-Day Browse, Chat, FAQ, Photoshare, and much more:

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kpaviat(at)verizon.net
Guest

Posted: Mon Aug 07, 2006 12:26 pm Post subject: 912S engine vibration

The gearbox should be serviced by qualified personnel with proper equipment

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riddon(at)sent.com
Guest

Posted: Mon Aug 07, 2006 1:51 pm Post subject: 912S engine vibration

Thanks Kim.  

   

I did check the friction torque at 200 hours as per Rotax manual and I also have a ‘tame’ Rotax engineer who lives close to me so I have checked with him.  I am intending to re check the friction torque next time I have the lid off the engine.  

   

I use Shell VSX4 engine oil which is a motorbike oil as recommended by Rotax which is suitable for engine and gearbox lube..  

   

Thanks for the feedback.  

   

Regards,  

   

Richard.   

   

-----Original Message-----

 From: owner-europa-list-server(at)matronics.com [mailto:owner-europa-list-server(at)matronics.com] On Behalf Of Kim Prout

 Sent: 07 August 2006 21:28

 To: europa-list(at)matronics.com

 Subject: Re: 912S engine vibration  

   

The gearbox should be serviced by qualified personnel with proper equipment. Having said that, the equipment needed is a hydraulic press with the correct mandrel to compress the disc springs that are used to “pre-load” the assembly against the driving dog hub. You can check the pre-load as part of the normal inspection process. Lock the crankshaft in place and use a spring scale to pull the propeller back and forth to determine the sliding force needed. The newest bulletin regarding this states the friction pre-load to be higher than before. I can’t remember the bulletin numbers but check out the Rotax list for that. If you have a slipper clutch, the check is similar but I believe the pre-load values are different. You can get the exploded views for the parts on line or check out the parts manual. The overhaul manual provides details also. 

 When the gearbox is removed, you can easily check the condition of the primary gear set. 

 Be sure to use the approved engine oil(s) that contain a gearing additive. Rotax does not allow you to add your own gear oil to the motor oil. 

 Hope this helps!

 kp

- The Matronics Europa-List Email Forum -

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