Matronics Email Lists :: View topic - Mysterious vibration on Europa Tri Gear

Matronics Email Lists
Web Forum Interface to the Matronics Email Lists

Get Email Distribution Too! FAQ Search Memberlist Usergroups Register

Profile Log in to check your private messages Log in

Mysterious vibration on Europa Tri Gear

Matronics Email Lists Forum Index -> Europa-List

View previous topic :: View next topic

Author Message

GBWFH2010

Joined: 31 Jul 2011
Posts: 38

Posted: Sun Jul 31, 2011 10:13 am Post subject: Mysterious vibration on Europa Tri Gear

Aircaft: Europa Tri Gear

Engine: Rotax 912 UL

Propeller: Airmaster 322

Help! I would welcome any advice or suggestions regarding a problem which is afflicting my aircraft. It has developed a strange vibration/resonance which occurs after establishing the cruise. For example, after a normal take off and climb I set the prop to Cruise, reduce the MFP to 26â€  which gives approx. 100Kts at an indicated 5200 RPM. Everything appears â€˜normalâ€™ at this stage. If I increase the cruise setting to 27â€, or greater, everything remains smooth, but reducing back to 26â€ re-introduces the vibration (which is noticeable unless the throttle is reduced almost to idle), which although it does not shake the aircraft to pieces, is most noticeable. The vibration remains through reduced throttle settings and can only be cleared temporarily by adjusting prop pitch to use a higher RPM and power settings. 



Initially I was convinced it was a propeller issue, but detailed checks have so far failed to highlight any problem. Airmaster are convinced it is not their propeller at fault but gave me several thing to check, all of which I have done. Europa suggested the prop carbon brushes and tracking should be cleaned which I have done. For a while I thought this might have cleared the fault, but it returned after 55 mins of flight. Interestingly At the same time as I had cleaned the tracking I had removed the whole exhaust system for inspection. I could not find anything wrong, no holes, or loose pipes so I refitted it and lock wired everything.



I have inspected the carburettors, replaced the rubber mountings and balanced the system and everything appears to be normal.  



I have to admit I am at a loss to know what to check next. It may be related to something that was removed and refitted during the exhaust inspection, but I cannot find anything obvious and  I do not understand why the problem is not apparent as soon as cruise power is applied. 



I would welcome any thoughts on this matter as it is driving me mad!

_________________
Gordon Grant

G-BWFH

rparigoris

Joined: 24 Nov 2009
Posts: 792

Posted: Sun Jul 31, 2011 11:07 am Post subject: Re: Mysterious vibration on Europa Tri Gear

Hi Gordon



A few thoughts:

**Although you stated that you have balanced the carbs, did you check that they are being opened the same throughout the throttle range? Do you have a kinked or otherwise compromised set of cables? Did you try balancing at around the throttle position you are having a problem? 

**Are your carb float bowl vents in good condition and both plumbed to approx. ambient pressure? 

**If you switch from both to left then right mag, is there a change?

**I am not sure, did you check the tracking of the blades? Did you measure that the blades are the same pitch, especially at the approx pitch where you are having vibrations?

**Did you ever dynamic balance the blades?

**Did you do the mod to undercarriage mounting frame? Is it or the motor mount cracked? Is the engine mounting bolts (Binx nuts) properly torqued? Are the motor mounts in OK condition?

**Is the choke (enriching circuit) cables completely closing the arms?

**Is there a leak in the balancing tube?

**When was the last time you replaced the spark plugs? Is there a chance you may have wires that got mixed up?

**Is the spinner tight with screws tight and no cracks and does it track true? Is the backing plate cracked? Did you by chance install different hardware where on the spinner, back plate or other is causing the prop to be out of balance?

** How many hours on your gearbox since it was checked? Do you have a slipper clutch? Do you use 100LL a lot? do you have a problem starting?



Have a look through here, especially vibration:

http://www.europaowners.org/forums/gallery2.php?g2_itemId=81550



Ron Parigoris

Rocketman

Joined: 07 Sep 2010
Posts: 87
Location: USA, Earth

Posted: Sun Jul 31, 2011 12:29 pm Post subject: Mysterious vibration on Europa Tri Gear

Gordon,



Just for giggles, clean and re-lubricate the throttle cables and insure 

that there is no binding in the system, check the return springs, that 

they are plenty strong, then re-balance the carbs at the exact rpm the 

vibration is occurring.  Also, be very sure that no exhaust gas is 

making it's way up to the carb bowl area.  This should rule out a leaky 

exhaust system (causing vapor lock) and any carb balance issue.  The 

very design of the throttle cable system causes the carbs to go slightly 

in and out of sync, as the throttle in manipulated, due to the cables 

changing length, slightly, in relation to each other.  Nothing to lose 

but time and everything to gain...



Jeff - Baby Blue

600+ hours



On 7/31/2011 1:13 PM, GBWFH2010 wrote:

 	  Quote: 	
		   



 Aircaft: Europa Tri Gear

 Engine: Rotax 912 UL

 Propeller: Airmaster 322

 Help! I would welcome any advice or suggestions regarding a problem which is afflicting my aircraft. It has developed a strange vibration/resonance which occurs after establishing the cruise. For example, after a normal take off and climb I set the prop to Cruise, reduce the MFP to 26â€  which gives approx. 100Kts at an indicated 5200 RPM. Everything appears â€˜normalâ€™ at this stage. If I increase the cruise setting to 27â€, or greater, everything remains smooth, but reducing back to 26â€ re-introduces the vibration (which is noticeable unless the throttle is reduced almost to idle), which although it does not shake the aircraft to pieces, is most noticeable. The vibration remains through reduced throttle settings and can only be cleared temporarily by adjusting prop pitch to use a higher RPM and power settings.



 Initially I was convinced it was a propeller issue, but detailed checks have so far failed to highlight any problem. Airmaster are convinced it is not their propeller at fault but gave me several thing to check, all of which I have done. Europa suggested the prop carbon brushes and tracking should be cleaned which I have done. For a while I thought this might have cleared the fault, but it returned after 55 mins of flight. Interestingly At the same time as I had cleaned the tracking I had removed the whole exhaust system for inspection. I could not find anything wrong, no holes, or loose pipes so I refitted it and lock wired everything.



 I have inspected the carburettors, replaced the rubber mountings and balanced the system and everything appears to be normal.



 I have to admit I am at a loss to know what to check next. It may be related to something that was removed and refitted during the exhaust inspection, but I cannot find anything obvious and  I do not understand why the problem is not apparent as soon as cruise power is applied.



 I would welcome any thoughts on this matter as it is driving me mad!



 --------

 Gordon Grant



 G-BWFH





 Read this topic online here:



 http://forums.matronics.com/viewtopic.php?p=348173#348173





 -----

 No virus found in this message.

 Checked by AVG - www.avg.com

GBWFH2010

Joined: 31 Jul 2011
Posts: 38

Posted: Tue Aug 02, 2011 9:30 am Post subject: Re: Mysterious vibration on Europa Tri Gear

Ron, 



Thank you for your suggestions which are greatly appreciated. I have been working on the Europa today checking a number of the things you suggested. 



I found all cables to be in good condition and the physical operation of the carbs appears to be correct and in sync. I have yet to re balance, but I will explain why later. 

The carb bowl vents appear to be Ok and plumbed in and connected correctly.

Switching mags makes no difference to the noise.

The blades have been checked, are all at the same pitch and are within the manufacturers limits. A basic check of the tracking has been conducted and no problems highlighted. The blades have not been dynamically balanced.

I can find no damage to the engine mount, or mounting bolts which are torqued correctly. The aircraft was converted to a Tri Gear in 2007 â€“ which mod are you referring to?

The chokes are closing correctly, there is no leak in the balancing tube and the plugs were replaced last September.

The spinner is in good condition and on tight, with all screws checked and hub appears to be fine. No changes have been made to any part of the prop system.

I do not often use 100LL â€“ only 40 litres in 33 hours. The total engine time is 265 hours and as far as I know the gearbox has never been removed or checked. I have checked the slipper clutch friction torque and it was 24 ft lb â€“ well within the range stated by Rotax.  I never have any starting problems.

When I was checking the slipper clutch I removed the four upper spark plugs. I was surprised to find those from cyls 2 and 4 were very black and sooty but 1 and 3 were perfect. I checked the needle jet in the left carburettor and found the circlip located on the richest setting. I moved this down one notch, re-assembled the carburettor and test flew the aircraft. For nearly one hour it was perfect with no vibration at any cruise setting from 28 inches to 25 inches MFP, but after descending into the circuit and returning to cruise power the vibration/harmonic was very noticeable at 26 inches MFP. Obviously  I need to re-balance the carbs and I will do this tomorrow, but it does seem that working on the carburettors/air intake system seems to improve things for up to 60 mins and then the problem returns. 

Regards

_________________
Gordon Grant

G-BWFH

GBWFH2010

Joined: 31 Jul 2011
Posts: 38

Posted: Tue Aug 02, 2011 9:35 am Post subject: Re: Mysterious vibration on Europa Tri Gear

Jeff,



Thank you for your suggestions. I have checked all the cables and operation seems to be perfect. I have also had a good look for exhaust leaks and can not find any trace of any leaks - the system seems in good health. As explained to Ron I will be balancing the carbs tomorrow and will keep you posted.



Regards

_________________
Gordon Grant

G-BWFH

rparigoris

Joined: 24 Nov 2009
Posts: 792

Posted: Tue Aug 02, 2011 10:09 am Post subject: Mysterious vibration on Europa Tri Gear

Hi Gordon 

 	Reply below **** 

 	  

 	> --> Europa-List message posted by: "GBWFH2010" <gcgrant(at)supanet.com> 	> 	> Ron, 	> 	> Thank you for your suggestions which are greatly appreciated. I have been 	> working on the Europa today checking a number of the things you suggested. 	> 	> I found all cables to be in good condition and the physical operation of 	> the carbs appears to be correct and in sync. I have yet to re balance, but 	> I will explain why later. 	> The carb bowl vents appear to be Ok and plumbed in and connected 	> correctly. 	> Switching mags makes no difference to the noise. 	> The blades have been checked, are all at the same pitch and are within the 	> manufacturers limits. A basic check of the tracking has been conducted and 	> no problems highlighted. The blades have not been dynamically balanced. 

 	****Good idea to try and get rebalanced no matter. 

 	 	> I can find no damage to the engine mount, or mounting bolts which are 	> torqued correctly. The aircraft was converted to a Tri Gear in 2007 â&euro;&ldquo; 	> which mod are you referring to? 

 	****Mod 72: 

 	http://www.europa-aircraft.com/updates/mods.php 

 	****Below 5K the manifold does not provide equal mixing, think a very common problem. If you were to run at 5K for a while and turn off you would probably see nice color of plugs. i am not flying yet but do know Type 64 carbs. Adjusting idle needle as lean as you can may help. 

 	I checked the needle jet in the left 	> carburettor and found the circlip located on the richest setting. I moved 	> this down one notch, re-assembled the carburettor and test flew the 	> aircraft. For nearly one hour it was perfect with no vibration at any 	> cruise setting from 28 inches to 25 inches MFP, but after descending into 	> the circuit and returning to cruise power the vibration/harmonic was very 	> noticeable at 26 inches MFP. Obviously I need to re-balance the carbs and 	> I will do this tomorrow, but it does seem that working on the 	> carburettors/air intake system seems to improve things for up to 60 mins 	> and then the problem returns. 

 	****Be very careful messing with main jets and jet needle settings. Verify and clean jets, my 914 has different main jets and different jet needle positions I think from the factory. 

 	  

 	Go after carbs. Even though the enriching circuit is not supposed to do much in cruise, you can try pulling choke at cruise and see if that makes a difference. Perhaps ask Bud or Airmaster if you can try and switching blades? 

 	  

 	Good luck 

 	Ron P. 

 	  

 	  

 	  

 	 	> Regards 	> 	> -------- 	> Gordon Grant 	> 	> G-BWFH 	> 	> 	> 	> 	> Read this topic online here: 	> 	> http://forums.matronics.com/viewtopic.php?p=348399#348399 	> 	> 	> 	> 	> 	> 	> 	> 	> 	> 	>    [quote][b]

rehn(at)rockisland.com
Guest

Posted: Tue Aug 02, 2011 10:47 am Post subject: Mysterious vibration on Europa Tri Gear

Just another thought. Could it be airframe related not engine? Does it happen only at lower airspeeds? Perhaps as you slow down a vibration sets up maybe in the cowling or baffles in the cowling vibrating? Have you made any changes in those areas or something loosening up?

Worth a look maybe.

Jerry



--

nigel henry

Joined: 24 Feb 2011
Posts: 16
Location: oxford uk

Posted: Tue Aug 02, 2011 2:21 pm Post subject: Mysterious vibration on Europa Tri Gear

Not read the thread  but   prop tips check for cracks running from the tip use a magnifying glass,tape each prop tip the same amount oI could not see the tip cracks till it became a problem. Undercarriage leg covers check and wind with 

electrical tape also check any resin covers like flaps  of fairings  cowling and bits check for vibration  I have a sailing yacht   and the long runs of rope hum under tension and wind cowls can resonate   hope it helps      but record the noise   to us somebody knows the noise  x x x  

 	  Quote: 	
		   Subject: Re: Mysterious vibration on Europa Tri Gear

 From: gcgrant(at)supanet.com

 Date: Tue, 2 Aug 2011 10:30:42 -0700

 To: europa-list(at)matronics.com

 --> Europa-List message posted by: "GBWFH2010" <gcgrant(at)supanet.com>

 Ron, 

 Thank you for your suggestions which are greatly appreciated. I have been working on the Europa today checking a number of the things you suggested. 

 I found all cables to be in good condition and the physical operation of the carbs appears to be correct and in sync. I have yet to re balance, but I will explain why later. 

 The carb bowl vents appear to be Ok and plumbed in and connected correctly.

 Switching mags makes no difference to the noise.

 The blades have been checked, are all at the same pitch and are within the manufacturers limits. A basic check of the tracking has been conducted and no problems highlighted. The blades have not been dynamically balanced.

 I can find no damage to the engine mount, or mounting bolts which are torqued correctly. The aircraft was converted to a Tri Gear in 2007 â€“ which mod are you referring to?

 The chokes are closing correctly, there is no leak in the balancing tube and the plugs were replaced last September.

 The spinner is in good condition and on tight, with all screws checked and hub appears to be fine. No changes have been made to any part of the prop system.

 I do not often use 100LL â€“ only 40 litres in 33 hours. The total engine time is 265 hours and as far as I know the gearbox has never been removed or checked. I have checked the slipper clutch friction torque and it was 24 ft lb â€“ well within the range stated by Rotax.  I never have any starting problems.

 When I was checking the slipper clutch I removed the four upper spark plugs. I was surprised to find those from cyls 2 and 4 were very black and sooty but 1 and 3 were perfect. I checked the needle jet in the left carburettor and found the circlip located on the richest setting. I moved this down one notch, re-assembled the carburettor and test flew the aircraft. For nearly one hour it was perfect with no vibration at any cruise setting from 28 inches to 25 inches MFP, but after descending into the circuit and returning to cruise power the vibration/harmonic was very noticeable at 26 inches MFP. Obviously  I need to re-balance the carbs and I will do this tomorrow, but it does seem that working on the carburettors/air intake system seems to improve things for up to 60 mins and then the problem returns. 

 Regards

 --------

 Gordon Grant

 G-BWFH

 Read this topic online here:

 http://forums.matronics.com/viewtopic.php?p=348399#348399

=====================

 	  Quote: 	
		   _====

  [quote][b]

frans(at)privatepilots.nl
Guest

Posted: Tue Aug 02, 2011 11:30 pm Post subject: Mysterious vibration on Europa Tri Gear

For what it is worth:

I have a small piece of tape to cover the hole of the rear wing pip

pins. Recently the aft end of this tape came loose and I had 1 inch of

tape end vibrating in the wind.

Unaware of this, I was strucked by a sudden buzzing vibration through

the ship. It behaved like described, with some speeds or prop settings

it was gone, to return at certain speeds, but a few times by temporarily

change a few parameters I could get it to stay away for a while.

I'm still surprised how difficult it was to determine what the source of

the vibration was, and how much vibration just 1 inch of tape can

create. The sound of it was much louder than the engine sound and it

appeared to come from everywhere.

I was worried enough to consider an immediate off field landing (it

could be flutter, or some critical part about to be teared off) but

decided to wait a little to see how it would develop. At least the

controls felt completely normal.

After the landing I discovered this small piece of tape, the end ragged

as a proof that it had been vibrating. After removing it the vibration

was gone and never returned.



Frans

Rocketman

Joined: 07 Sep 2010
Posts: 87
Location: USA, Earth

Posted: Wed Aug 03, 2011 10:26 am Post subject: Mysterious vibration on Europa Tri Gear

Frans,



You need some stronger tape... 



Jeff - Baby Blue



do not archive



On 8/3/2011 2:26 AM, Frans Veldman wrote:

 	  Quote: 	
		   



 For what it is worth:

 I have a small piece of tape to cover the hole of the rear wing pip

 pins. Recently the aft end of this tape came loose and I had 1 inch of

 tape end vibrating in the wind.

 Unaware of this, I was strucked by a sudden buzzing vibration through

 the ship. It behaved like described, with some speeds or prop settings

 it was gone, to return at certain speeds, but a few times by temporarily

 change a few parameters I could get it to stay away for a while.

 I'm still surprised how difficult it was to determine what the source of

 the vibration was, and how much vibration just 1 inch of tape can

 create. The sound of it was much louder than the engine sound and it

 appeared to come from everywhere.

 I was worried enough to consider an immediate off field landing (it

 could be flutter, or some critical part about to be teared off) but

 decided to wait a little to see how it would develop. At least the

 controls felt completely normal.

 After the landing I discovered this small piece of tape, the end ragged

 as a proof that it had been vibrating. After removing it the vibration

 was gone and never returned.



 Frans

 -----

 No virus found in this message.

 Checked by AVG - www.avg.com

watervet(at)mweb.co.za
Guest

Posted: Thu Aug 04, 2011 12:18 am Post subject: Mysterious vibration on Europa Tri Gear

Hi Gordon,



We had a similar problem with my Trigear XS with 914 Rotax - and after many hours of carb stripping and cleaning and balancing with a mercury manometer - we could not fix it till - we re-stripped the carbs and found a small defect on the base of one of the float chamber needles that caused the needle to "cock" to one side from time to time( we think) - we renewed needles and the float actuator arms - re- balanced the carbs and hey presto problem gone. The aircraft had stood for a while prior to the problem.



Regards

Mike Toft

Europa XS Trigear 914 Airmaster



On 31 Jul 2011, at 9:07 PM, rparigoris wrote:



 	  Quote: 	
		   

 

 Hi Gordon

 

 A few thoughts:

 **Although you stated that you have balanced the carbs, did you check that they are being opened the same throughout the throttle range? Do you have a kinked or otherwise compromised set of cables? Did you try balancing at around the throttle position you are having a problem? 

 **Are your carb float bowl vents in good condition and both plumbed to approx. ambient pressure? 

 **If you switch from both to left then right mag, is there a change?

 **I am not sure, did you check the tracking of the blades? Did you measure that the blades are the same pitch, especially at the approx pitch where you are having vibrations?

 **Did you ever dynamic balance the blades?

 **Did you do the mod to undercarriage mounting frame? Is it or the motor mount cracked? Is the engine mounting bolts (Binx nuts) properly torqued? Are the motor mounts in OK condition?

 **Is the choke (enriching circuit) cables completely closing the arms?

 **Is there a leak in the balancing tube?

 **When was the last time you replaced the spark plugs? Is there a chance you may have wires that got mixed up?

 **Is the spinner tight with screws tight and no cracks and does it track true? Is the backing plate cracked? Did you by chance install different hardware where on the spinner, back plate or other is causing the prop to be out of balance?

 ** How many hours on your gearbox since it was checked? Do you have a slipper clutch? Do you use 100LL a lot? do you have a problem starting?

 

 Have a look through here, especially vibration:

 http://www.europaowners.org/forums/gallery2.php?g2_itemId=81550

 

 Ron Parigoris

 

 

 

 

 Read this topic online here:

 

 http://forums.matronics.com/viewtopic.php?p=348176#348176

GBWFH2010

Joined: 31 Jul 2011
Posts: 38

Posted: Thu Aug 04, 2011 4:14 am Post subject: Re: Mysterious vibration on Europa Tri Gear

Yesterday I balanced the carbs and test flew the aircraft. It was beautifully smooth in the climb and cruise. I could initiate the noise by reducing the throttle setting to below 25inches MFP, but everything returned to normal at cruise power. Until I descended to join the circuit, when the noise became apparent at cruise setting after descending to the circuit height of 1000 ft. It was not as bad as previously as I could smooth it out by slightly increasing power and it disappeared when selecting Climb pitch on the downwind leg. Overall a great improvement.



I was very interested in Mike Toft's experience which seem very similar to mine and although I have not ruled anything out everything seems to be pointing to carburation. I think I will do the same as Mike and see what happens.

_________________
Gordon Grant

G-BWFH

ptag.dev(at)tiscali.co.uk
Guest

Posted: Thu Aug 04, 2011 10:23 am Post subject: Mysterious vibration on Europa Tri Gear

Hi! Gordon .

Have you checked your magnetic plug for ferrous swarf debris? I recommend

you to do this as if it were mandatory( I believe it to be at every 100

hours ) but I recommend it checked every oil change..

I have good reason to believe it is possible the anti -chatter drive dogs

are exhibiting back lash chatter. Propeller wind milling effect will allow

the lower RPM/drive torque position to be reached earlier and so allow the

drive dog/cams to be working together on a minimum bearing area  of male

nose and female trough. It may well be that you need the propeller backlash

tightening up with shims .(This is not referring to the crankshaft

protection slipper clutch mounted between the propeller and the back lash

device. Whilst I'm not purporting to be an expert I have god reason to pass

this advice.

Do the check and also measure the prop. Torque "break out" load at 24 "

radius to see if it is in spec. If you are sure your carbs are

sinchronised/balanced first then this is the way to go for peace of mind.

I'm thinking I have the same "tee" shirt. Please let us know your outcome.

And what engine you have.?

Regards

Bob Harrison  G-PTAG



--

Display posts from previous:

	Matronics Email Lists Forum Index -> Europa-List	All times are GMT - 8 Hours
Page 1 of 1

Jump to:

You cannot post new topics in this forum
You cannot reply to topics in this forum
You cannot edit your posts in this forum
You cannot delete your posts in this forum
You cannot vote in polls in this forum
You cannot attach files in this forum
You can download files in this forum