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air.guerner(at)wanadoo.fr
Guest

Posted: Sun Jun 24, 2007 1:05 am Post subject: Tailplane flutter

<?xml:namespace prefix = o ns = "urn:schemas-microsoft-com:office:office" />Hi all, 

  

The half inch play tolerance as specified by the factory means that, in a more than one degree range, the tailplanes are not balanced at all. This is a possible cause for flutter. I consider that any play in the chain between the mass balance arm and the tailplanes is unacceptable: that means zero play between TP4 and TP9 and zero play between TP 4 and TP12. The factory solution is Mod 62: replacement of the Â¼â€ pins by 3/8â€ pins. This mod is known to only delay, not eliminate, the problem. As far as I know, there are 3 solutions which have been implemented successfully by builders: 

-         gluing TP9 and TP12 to TP4 

-         replace the straight pins TP14C and TP14D by AN486 taper pins 

-         replace the straight pins TP14C and TP14D by AN bolts 

As some builders have mentioned in this forum in the past, all these solutions have their own inconveniences and must be implemented carefully, but I believe these inconveniences are far outweighed by the safety of a fully balanced tailplane in all conditions.  

Regards 

  

Remi Guerner 

F-PGKL, XS S/N395 monowheel,  912S, Airmaster, 482 hours   

    [quote][b]

willie.harrison(at)tinyon
Guest

Posted: Sun Jun 24, 2007 1:45 am Post subject: Tailplane flutter

I did Mod 62 and it seemed a big improvement (all holes drilled and reamed in a machine shop). 120 flying hours later it developed "a tad" of slop on one side. I have loctited that side (therefore could still remove the torque tube since loctite is on one side only). Is the idea of the AN bolt option that it clamps the two parts together? Is this a PFA approved mod?



Willie

 	  Quote: 	
		  Hi all,

 

The half inch play tolerance as specified by the factory means that, in a more than one degree range, the tailplanes are not balanced at all. This is a possible cause for flutter. I consider that any play in the chain between the mass balance arm and the tailplanes is unacceptable: that means zero play between TP4 and TP9 and zero play between TP 4 and TP12. The factory solution is Mod 62: replacement of the ¼” pins by 3/8” pins. This mod is known to only delay, not eliminate, the problem. As far as I know, there are 3 solutions which have been implemented successfully by builders:

-         gluing TP9 and TP12 to TP4

-         replace the straight pins TP14C and TP14D by AN486 taper pins

-         replace the straight pins TP14C and TP14D by AN bolts

As some builders have mentioned in this forum in the past, all these solutions have their own inconveniences and must be implemented carefully, but I believe these inconveniences are far outweighed by the safety of a fully balanced tailplane in all conditions. 

Regards

 

Remi Guerner

F-PGKL, XS S/N395 monowheel,  912S, Airmaster, 482 hours  

 

	




 [quote][b]

g-iani(at)ntlworld.com
Guest

Posted: Sun Jun 24, 2007 2:14 am Post subject: Tailplane flutter

William

  

 The  idea of the bolt option is that it does two things.  a) It clamps the two  parts together. b) to ensure the tubes stay round a cross drilled spacer is  fitted inside the TP4 tube.  This is Loctited in.  So you have both  clamping and a glue joint but retain the ability to  dismantle.

  

 This  is not PFA approved at present but has been discussed with Andy Draper in  2005.

  

 Francis Donaldson asked me on Friday to pool any ideas we have on  eliminating slop in this area.  He wants to address this as part of any  solution to the present problems.  I will have a document ready for him, by  tonight, summarising all the options (existing pins, big pins, taper pins, Bobs  blocks and bolts).  If anyone can think of anything else I will be glad to  hear from them.

  

 If the  PFA decides that bolts is the way to go, then we will have it documented and  approved very quickly.

  

 

  

 Ian Rickard  #505 G-IANI XS Trigear

Europa Club Mods Rep  (Trigear)

e-mail mods(at)europaclub.org.uk  

   or direct  g-iani(at)ntlworld.com 

  

    [quote][b]

ami(at)mcfadyean.freeserv
Guest

Posted: Sun Jun 24, 2007 2:14 am Post subject: Tailplane flutter

Remi,

 I'm not sure about that.

 I had to replace my outer TP pins at 15  hours.

 300++ hours later they are still OK, despite  operating mostly from grass strips.

  

 In my opinion, the pins are very accurately made.  But the holes in the TP tubes are not. My new pins were set-up so that they had  to be driven in; I suspect this makes the difference. The PFA requirement is now  for an "interference" fit.

  

 Duncan McF.

 [quote]   ---

willie.harrison(at)tinyon
Guest

Posted: Sun Jun 24, 2007 3:08 am Post subject: Tailplane flutter

Thanks Ian

The bolted option sounds like good engineering if done properly.



One other idea I have heard suggested, (by Tony Kay) is that a snug fitting inner tube is assembled, eg with Bearing Fit /retainer grade Loctite, into the torque tube, basically to make the whole thing thicker-walled and therefore to reduce the contact stress of the pin/tube contact areas. I think it would be a machine shop job to get the drilling and reaming done accurately so obviously the torque tube would have to come out. 



The other option might be simply to junk the existing torque tube and substitute something beefier (thicker walled and or harder). Not sure how the CofG works out for a mono but most trigears seem to have a hefty lump of lead in the tail so they could presumably take the extra weight of a reinforced or beefier torque tube with a corresponding reduction in the ballast weight.



By the way, I think it is highly enlightened of Francis to invite ideas from owner/builders. Most of us know from uncomfortable experience what practical implications are  put on any solution by the access issue, to say nothing of being "stakeholders" in the success of the outcome.



Thanks for your good work.



Willie Harrison



On 24 Jun 2007, at 11:13, G-IANI wrote:

[quote]  William

  

 The idea of the bolt option is that it does two things.  a) It clamps the two parts together. b) to ensure the tubes stay round a cross drilled spacer is fitted inside the TP4 tube.  This is Loctited in.  So you have both clamping and a glue joint but retain the ability to dismantle.

  

 This is not PFA approved at present but has been discussed with Andy Draper in 2005.

  

 Francis Donaldson asked me on Friday to pool any ideas we have on eliminating slop in this area.  He wants to address this as part of any solution to the present problems.  I will have a document ready for him, by tonight, summarising all the options (existing pins, big pins, taper pins, Bobs blocks and bolts).  If anyone can think of anything else I will be glad to hear from them.

  

 If the PFA decides that bolts is the way to go, then we will have it documented and approved very quickly.

  

 

  

 Ian Rickard  #505 G-IANI XS Trigear

Europa Club Mods Rep (Trigear)

e-mail mods(at)europaclub.org.uk (mods(at)europaclub.org.uk)  

   or direct g-iani(at)ntlworld.com (g-iani(at)ntlworld.com) 

  

  	  Quote: 	
		  

href="http://www.matronics.com/Navigator?Europa-List">http://www.matronics.com/Navigator?Europa-List

href="http://forums.matronics.com">http://forums.matronics.com



	
[b]

grahamsingleton(at)btinte
Guest

Posted: Sun Jun 24, 2007 4:11 am Post subject: Tailplane flutter

Duncan

I think they always were supplied as an interference fit.

I've noticed, however, that once they have been in and out more than 

once they loosen up. Pushing a drill through to drill the nylon bush is 

an awful thing to do to an accurate hole.



Better way might be to supply the nylon bush pre drilled, then bond in 

the bronze bushes to fit the position of the nylon instead of the other 

way round.



Re write the plans a bit?



Graham



Duncan & Ami McFadyean wrote:

 	  Quote: 	
		   Hi all, 

 Remi,

 I'm not sure about that.

 I had to replace my outer TP pins at 15 hours.

 300++ hours later they are still OK, despite operating mostly from grass 

 strips.

  

 In my opinion, the pins are very accurately made. But the holes in the 

 TP tubes are not. My new pins were set-up so that they had to be driven 

 in; I suspect this makes the difference. The PFA requirement is now for 

 an "interference" fit.

  

 Duncan McF.

g-iani(at)ntlworld.com
Guest

Posted: Sun Jun 24, 2007 4:17 am Post subject: Tailplane flutter

William

  

 Thanks  for the reminder that thick wall tube is another solution.

  

  

Ian Rickard  #505 G-IANI XS Trigear

Europa Club Mods Rep  (Trigear)

e-mail mods(at)europaclub.org.uk  

   or direct  g-iani(at)ntlworld.com 

 [quote]   

    

[b]

ami(at)mcfadyean.freeserv
Guest

Posted: Sun Jun 24, 2007 5:32 am Post subject: Tailplane flutter

Graham,

I agree that they loosen up on repeated  fitment, yet I had taken great care 

to minimise this during the build (fitting back together only twice, less 

than which was not possible).



As such, unless marginally oversize pins are supplied for the final fitting, 

the design is invalidated by the build process.



Duncan McF.

---

josok-e(at)ukolo.fi
Guest

Posted: Sun Jun 24, 2007 5:42 am Post subject: Tailplane flutter

Ian,



Slop on the tail planes is far from a new problem, it has frequently been  

reported before.

Looking through history, there has been written a lot and several  

solutions have allready been suggested.



Until now, it has not been causing an accident, now it happened everybody  

seems to look at it as a new problem, which it is not.



One of them is the clamp system that Bob Harrison developed.

Is that not reliable or not usefull or why is it not mentioned in this  

respect?



Regards,



Jos Okhuijsen



-- 

workshopcam http://www.okhuijsen.org/plane

http://www.europaowners.org/kit600

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

Posted: Sun Jun 24, 2007 6:32 am Post subject: Tailplane flutter

Hi! Remi  

You forgot my torque tube clamps as a permanent fix for no slop ever.  

Regards  

Bob Harrison G-PTAG   

     

Robt.C.Harrison  

  

   

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

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

 Sent: 24 June 2007 09:56

 To: europa-list(at)matronics.com

 Subject: Tailplane flutter  

   

Hi all,  

   

The half inch play tolerance as specified by the factory means that, in a more than one degree range, the tailplanes are not balanced at all. This is a possible cause for flutter. I consider that any play in the chain between the mass balance arm and the tailplanes is unacceptable: that means zero play between TP4 and TP9 and zero play between TP 4 and TP12. The factory solution is Mod 62: replacement of the ¼” pins by 3/8” pins. This mod is known to only delay, not eliminate, the problem. As far as I know, there are 3 solutions which have been implemented successfully by builders:  

-         gluing TP9 and TP12 to TP4  

-         replace the straight pins TP14C and TP14D by AN486 taper pins  

-         replace the straight pins TP14C and TP14D by AN bolts  

As some builders have mentioned in this forum in the past, all these solutions have their own inconveniences and must be implemented carefully, but I believe these inconveniences are far outweighed by the safety of a fully balanced tailplane in all conditions.   

Regards  

   

Remi Guerner  

F-PGKL, XS S/N395 monowheel,  912S, Airmaster, 482 hours    

   [quote] [b]

jp(at)brannenworks.com
Guest

Posted: Sun Jun 24, 2007 6:37 am Post subject: Tailplane flutter

Is the tail flutter problem the consequence of having 

easily removable stabilators?

jp

--- "R.C.Harrison" <ptag.dev(at)tiscali.co.uk> wrote:



[quote] Hi! Remi

 You forgot my torque tube clamps as a permanent fix

 for no slop ever.

 Regards

 Bob Harrison G-PTAG

  

 Robt.C.Harrison

  

 --

willie.harrison(at)tinyon
Guest

Posted: Sun Jun 24, 2007 6:59 am Post subject: Tailplane flutter

Hi Bob

Where can I access details of your clamp design?



Cheers



Willie Harrison

On 24 Jun 2007, at 15:30, R.C.Harrison wrote:

[quote]

Hi! Remi

You forgot my torque tube clamps as a permanent fix for no slop ever.

Regards

Bob Harrison G-PTAG

 

Robt.C.Harrison



[b]

mau11(at)free.fr
Guest

Posted: Sun Jun 24, 2007 8:52 am Post subject: Tailplane flutter

Hi  Robert,

  

 Do you  have pictures and/or scheme of your solution?

 Thanks

 Michel  Auvray

 Builder N°145

 [quote]   -----Message d'origine-----

De :    owner-europa-list-server(at)matronics.com    [mailto:owner-europa-list-server(at)matronics.com]De la part de    R.C.Harrison

Envoyé : dimanche 24 juin 2007    16:31

À : europa-list(at)matronics.com

Objet : RE:    Tailplane flutter

      

Hi! Remi   

You forgot my torque    tube clamps as a permanent fix for no slop ever.   

Regards   

Bob Harrison    G-PTAG   

       

Robt.C.Harrison

   

    

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

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

Sent: 24 June 2007 09:56

To: europa-list(at)matronics.com

Subject: Tailplane    flutter   

    

Hi    all,   

    

The half inch play tolerance as    specified by the factory means that, in a more than one degree range, the    tailplanes are not balanced at all. This is a possible cause for flutter. I    consider that any play in the chain between the mass balance arm and the    tailplanes is unacceptable: that means zero play between TP4 and TP9 and zero    play between TP 4 and TP12. The factory solution is Mod 62: replacement of the    ¼” pins by 3/8” pins. This mod is known to only delay, not eliminate, the    problem. As far as I know, there are 3 solutions which have been implemented    successfully by builders:   

-            gluing TP9 and    TP12 to TP4   

-            replace the    straight pins TP14C and TP14D by AN486 taper pins   

-            replace the    straight pins TP14C and TP14D by AN bolts   

As some builders have mentioned in    this forum in the past, all these solutions have their own inconveniences and    must be implemented carefully, but I believe these inconveniences are far    outweighed by the safety of a fully balanced tailplane in all conditions.       

Regards   

    

Remi    Guerner   

F-PGKL, XS S/N395 monowheel,  912S, Airmaster, 482 hours     

  	  Quote: 	
		   



href="http://www.matronics.com/Navigator?Europa-List">http://www.matronhref="http://forums.matronics.com">http://forums.matronics.com



	
[b]

carl(at)flyers.freeserve.
Guest

Posted: Sun Jun 24, 2007 10:35 am Post subject: Tailplane flutter

There is a slight misunderstanding regarding where  the wear in the "torque tube assembly" occurrs. The torque tube itself is a  hardened (possibly crome moly) steel.

  

 Having just implemented Mod 62 we found that there  was no noticeable wear in the torque tube itself. All the wear occurred in the  TP9 and TP12 components as these do not appear to be hardened steel (or as hard  as the torque tube itself).

  

 You are right about the reaming needing to be done  accurately and it is advisable to drill each hole from the outside and not  through the tube. The reaming should also be done from the outside and not  through the opposing holes. The factory specified drill size and reamer is  crucial (23/64 drill and 3/8 reamer) - dont be tempted to use a 3/8 or  9.5mm drill - it will ruin the job. Incidentally we measured the factory  supplied pins and found them to be a couple of thou oversize which is probably a  good thing.

  

 The factory instructions say you should ream  through the whole assembly but our experience was that this opened the holes out  too much with a slightly looser fit. We practiced on a spare piece of mild  steel tube before risking our engineering skills on the real thing. The purists  among you will say this leads to misalignment of the holes however under  the circumstances we found this simply made for a tighter fit.

  

 We drilled and reamed all the holes individually  making sure the opposing hole had a TP14 pin inserted half way. We then  assembled the whole assembly once on the workbench and it was necessary to  lightly hammer all the pins into place.

  

 We thought it prudent to assemble at least once in  case of a possible misalignment even though this process will have started to  wear the pin holes. The risk of discovering the misalignment down the back end  of the tailplane and the attendant possibility of being unable to remove the  pins was not an option we wanted to contemplate. In the final event a fair  amount of tapping with a hammer was needed to fully drive the pins home but has  resulted in an excellent solid fit. Only time will tell how good a job this  makes.

  

 Carl Pattinson

 G-LABS

  

 PS: Im not sure the bolted option will prevent  wear/ elongation of the holes.  I had a Shadow pre the Europa and a lot of  the tubular components were held together using bolts - in time the holes still  elongated.

  

 I did suggest to Andy that perhaps building the  counterweights into the leading edge of the tailplanes would eliminate the need  for the counterbalance arm but he was quick to point out this would require  a substantial increase in the weight needed due to the relatively short distance  between the torque tube and leading edges. Ultimately this may not be as big a  problem as it seems since many Europas with heavy VP props have additional  weight in the rear anyway. If this could be used to counterbalance the tailplane  it would be likking two birds with one stone.

  

 Still I am not a design engineer and I havent done  the sums - and wouldnt know how to.

  

  

 [quote]   ---

carl(at)flyers.freeserve.
Guest

Posted: Sun Jun 24, 2007 10:48 am Post subject: Tailplane flutter

The final alignment could be checked by trial fitting the torque assembly 

using the shank of a 3/8" drill. The factory supplied pins are a couple of 

thou oversize which is probably deliberate. Fortunately we had the help of a 

licenced aircraft engineer who loaned his workshop and checked our pins with 

a micrometer screw guage. Not sure of the exact dimension but they were 

measurably oversize.



Or alternately make dummy pins from 3/8" steel stock - or aircraft quality 

bolts. They would need to be checked with a gague to ensure they were the 

correct size.



---

rparigor(at)suffolk.lib.n
Guest

Posted: Sun Jun 24, 2007 10:54 am Post subject: Tailplane flutter

Hello Ian



"Francis Donaldson asked me on Friday to pool any ideas we have on

eliminating slop in this area."



I am very happy with my resolution. I made pins out of 416SS ~.402" in

diameter. Interference fit between .0006" and .0008". I made a slight

dogbone (relief of a few thousands of an ") between interference contact

areas.



If I were to do it again I would make all the entrance holes slight larger

than the back side and eliminate the dogbone (I did this on a few holes).

I used paint primer as an assembly lubricant.



Search Ron Parigoris Torque Tube for a bit more detail on procedure.



A fixture for holding work is needed if the fit was as bad as mine

(trilobal holes, pins slide in with just gravity, way over 3/4"

differential motion at TE.



Burnishing is an essential (as described in my prior post) step for a true

interference fit.



Ron Parigoris

rparigor(at)suffolk.lib.n
Guest

Posted: Sun Jun 24, 2007 10:54 am Post subject: Tailplane flutter

Hello Ian



"Francis Donaldson asked me on Friday to pool any ideas we have on

eliminating slop in this area."



I am very happy with my resolution. I made pins out of 416SS ~.402" in

diameter. Interference fit between .0006" and .0008". I made a slight

dogbone (relief of a few thousands of an ") between interference contact

areas.



If I were to do it again I would make all the entrance holes slight larger

than the back side and eliminate the dogbone (I did this on a few holes).

I used paint primer as an assembly lubricant.



Search Ron Parigoris Torque Tube for a bit more detail on procedure.



A fixture for holding work is needed if the fit was as bad as mine

(trilobal holes, pins slide in with just gravity, way over 3/4"

differential motion at TE.



Burnishing is an essential (as described in my prior post) step for a true

interference fit.



Ron Parigoris

rparigor(at)suffolk.lib.n
Guest

Posted: Sun Jun 24, 2007 10:54 am Post subject: Tailplane flutter

Hello Ian



"Francis Donaldson asked me on Friday to pool any ideas we have on

eliminating slop in this area."



I am very happy with my resolution. I made pins out of 416SS ~.402" in

diameter. Interference fit between .0006" and .0008". I made a slight

dogbone (relief of a few thousands of an ") between interference contact

areas.



If I were to do it again I would make all the entrance holes slight larger

than the back side and eliminate the dogbone (I did this on a few holes).

I used paint primer as an assembly lubricant.



Search Ron Parigoris Torque Tube for a bit more detail on procedure.



A fixture for holding work is needed if the fit was as bad as mine

(trilobal holes, pins slide in with just gravity, way over 3/4"

differential motion at TE.



Burnishing is an essential (as described in my prior post) step for a true

interference fit.



Ron Parigoris

rparigor(at)suffolk.lib.n
Guest

Posted: Sun Jun 24, 2007 11:22 am Post subject: Tailplane flutter

Hello Duncan



"I agree that they loosen up on repeated  fitment"



Once you do what I refer to as burnishing, the hole size remains much more

stable. I suspect that not only does it smooth the inperfections of the

wall, but expands the metal just a bit where it becomes less resiliant to

change.



I talked to a guy who used to refirbish critical gear components of Gruman

carrier aircraft. Before final reaming, he would use a hydraulic expander

to first enlarge and stabalize hole.



Making a dogbone or first hole slight larger than the second goes even

further to preventing damaging fit.



Ron Parigoris

grahamsingleton(at)btinte
Guest

Posted: Sun Jun 24, 2007 2:51 pm Post subject: Tailplane flutter

Duncan

I think you are right. The surface finish on the pins might be 

unsuitable, maybe the grinding marks are rubbed off when fitting?

Graham



Duncan & Ami McFadyean wrote:

 	  Quote: 	
		   Graham,

 I agree that they loosen up on repeated  fitment, 

 

 As such, unless marginally oversize pins are supplied for the final 

 fitting, the design is invalidated by the build process.

 

 Duncan McF.

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