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Tailplane flutter
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grahamsingleton(at)btinte
Guest

Posted: Sun Jun 24, 2007 3:22 pm Post subject: Tailplane flutter

Carl

The torque tube is chrome plated 4130 I believe, stainless isn't strong 

enough.

You may have spotted the weakest link in the chain, if the TP9 & 12 had 

more bearing area the slop problem might go away. Wouldn't be much 

weight penalty either.

OTH clamp bolting as Nigel Graham did years ago might be the best answer.

Graham



Carl Pattinson wrote:

 	  Quote: 	
		   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).

air.guerner(at)wanadoo.fr
Guest

Posted: Mon Jun 25, 2007 12:08 am Post subject: Tailplane flutter

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

  

Sorry I missed your clamp solution. Anyway, I went the taper pin way. Easy to do and very effective. 

Remi 

  



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

Subject: RE: Europa-List: 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



--

nigel_graham(at)btconnect
Guest

Posted: Mon Jun 25, 2007 2:42 am Post subject: Tailplane flutter

Hi Graham,



FYI - I am working with Ian Rickard at the moment to document exactly what I

did and present this to the PFA.



To enlighten those of you not familiar with this mod:

A long time ago I identified the inherent shortfall with the TP14 method of

securing the drive arms to the torque tube. Merely replacing these pins with

oversized pins would not in my opinion, cure the problem - only delay the

next re-occurrence once play developed.



I developed a simple arrangement (KISS technology) that positively clamps

the drive arms (TP9 and TP12) onto the torque tube by replacing all four

TP14 pins with 1/4" x 2.125" AN bolts.

To support the torque tube and prevent it distorting, 15mm wide

cross-drilled discs are inserted into TP4 at each of the four stations.

To spread the clamping load over a larger surface, "saddle blocks" (profiled

to mate with the OD of TP9 and TP12) are fitted under the bolt head and

castellated nut.



The beauty of clamping is that it introduces a torque damper into the drive

system - eliminating the shock "chattering" that wears the standard TP14

pins and elongates the holes - and it can be retrofitted to tubes with worn

holes.



Nigel (The other one) Graham

--

grahamsingleton(at)btinte
Guest

Posted: Mon Jun 25, 2007 3:06 am Post subject: Tailplane flutter

Nigel

Hi! sorry to hear about your motor bike incident, get better soon.

Your mod is probably the neatest one and good engineering practice. I 

will be surprised if PFA don't like it, not invented here syndrome seems 

unlikely in this case. {{

Graham

Nigel Graham wrote:

 	  Quote: 	
		   

 

 Hi Graham,

 

 FYI - I am working with Ian Rickard at the moment to document exactly what I

 did and present this to the PFA.

willie.harrison(at)tinyon
Guest

Posted: Mon Jun 25, 2007 3:08 am Post subject: Tailplane flutter

Nigel,



Would there be any problem with doing this with 3/8 bolts on an  

aircraft which had Mod 62 already done to it?



This is such an appealing idea I think.



Willie





On 25 Jun 2007, at 11:29, Nigel Graham wrote:



[quote] 

 <nigel_graham(at)btconnect.com>



 Hi Graham,



 FYI - I am working with Ian Rickard at the moment to document  

 exactly what I

 did and present this to the PFA.



 To enlighten those of you not familiar with this mod:

 A long time ago I identified the inherent shortfall with the TP14  

 method of

 securing the drive arms to the torque tube. Merely replacing these  

 pins with

 oversized pins would not in my opinion, cure the problem - only  

 delay the

 next re-occurrence once play developed.



 I developed a simple arrangement (KISS technology) that positively  

 clamps

 the drive arms (TP9 and TP12) onto the torque tube by replacing all  

 four

 TP14 pins with 1/4" x 2.125" AN bolts.

 To support the torque tube and prevent it distorting, 15mm wide

 cross-drilled discs are inserted into TP4 at each of the four  

 stations.

 To spread the clamping load over a larger surface, "saddle  

 blocks" (profiled

 to mate with the OD of TP9 and TP12) are fitted under the bolt head  

 and

 castellated nut.



 The beauty of clamping is that it introduces a torque damper into  

 the drive

 system - eliminating the shock "chattering" that wears the standard  

 TP14

 pins and elongates the holes - and it can be retrofitted to tubes  

 with worn

 holes.



 Nigel (The other one) Graham

 --

kheindl(at)msn.com
Guest

Posted: Mon Jun 25, 2007 3:30 am Post subject: Tailplane flutter

Hi Nigel,



My main concern with this mod would be the insertion of the (predrilled) 

15mm discs into a tube with anti-corrosion paint on the inside. Would there 

be a suitable reamer to get it absolutely smooth, also to remove any burr 

from the enlarged holes. Then how do you aim to position the discs so that 

all the holes line up ? Maybe a threaded hole in the centre for attaching a 

long rod temporarily just for the lineup ?



Karl





[quote]From: "Nigel Graham" <nigel_graham(at)btconnect.com>

Reply-To: europa-list(at)matronics.com

To: <europa-list(at)matronics.com>

Subject: RE: Tailplane flutter

Date: Mon, 25 Jun 2007 11:29:20 +0100




<nigel_graham(at)btconnect.com>



Hi Graham,



FYI - I am working with Ian Rickard at the moment to document exactly what 

I

did and present this to the PFA.



To enlighten those of you not familiar with this mod:

A long time ago I identified the inherent shortfall with the TP14 method of

securing the drive arms to the torque tube. Merely replacing these pins 

with

oversized pins would not in my opinion, cure the problem - only delay the

next re-occurrence once play developed.



I developed a simple arrangement (KISS technology) that positively clamps

the drive arms (TP9 and TP12) onto the torque tube by replacing all four

TP14 pins with 1/4" x 2.125" AN bolts.

To support the torque tube and prevent it distorting, 15mm wide

cross-drilled discs are inserted into TP4 at each of the four stations.

To spread the clamping load over a larger surface, "saddle blocks" 

(profiled

to mate with the OD of TP9 and TP12) are fitted under the bolt head and

castellated nut.



The beauty of clamping is that it introduces a torque damper into the drive

system - eliminating the shock "chattering" that wears the standard TP14

pins and elongates the holes - and it can be retrofitted to tubes with worn

holes.



Nigel (The other one) Graham

--

nigel_graham(at)btconnect
Guest

Posted: Mon Jun 25, 2007 3:52 am Post subject: Tailplane flutter

Willie,



I can think of no reason why not.

The only point you need to check is the bolt head to rear bulkhead

clearance. The circumference of the TP9 and TP12 is only about 16mm away

from this bulkhead - so the total assembly thickness is a limiting factor

and I'm not sure how deep a 3/8" bolt head is.



If this did prove to be a problem, small 1/4" to 3/8" step-down spigots

would solve the problem and allow you to use 1/4" bolts.



Nigel (The other one)



--

nigel_graham(at)btconnect
Guest

Posted: Mon Jun 25, 2007 5:01 am Post subject: Tailplane flutter

Hi Karl,



You're clearly thinking this through!



My description was only an abstract to give an idea of the concept.

The detailed proposals handle preparation insertion and bonding.



Here is a description for those of you with an enquiring mind - I will not

take offence if the rest of you skip this!



TP4 has to be de-greased and de-burred inside prior to insertion. The discs

have a scribe line on one side to indicate the orientation of the cross

drill (facilitating alignment). You were on the money with regard to the

insertion tool. A 6.0mm threaded bar (with two lock  nuts) screws into a

central hole in the disc. This allows the discs to be inserted into TP4 and

rotated into correct alignment - two from one side and two from the other.



The discs have a shallow groove centrally around the circumference. Once in

position, bearing grade anaerobic adhesive (Loctite) is introduced through

one of the TP4 holes and the discs rotated to distribute the adhesive. This

ensures concentricity and accommodates any small variance of inside

diameter.

An AN4 bolt can be temporally inserted to locate the disc in the correct

position and the thread bar removed. In this way, all four discs are placed

and bonded. The 6mm holes also serve to cross vent the tube and provide a

method (via spray tube) of introducing the anti-corrosion treatment of your

choice (ACF50, WD40, Shell "Ensis" fluid, granny's beef dripping) into TP4.



Once bonded, the tail can be re-assembled. The bolts have to be inserted

from the rear to guarantee clearance with the rear bulkhead. This will

involve rotating the TP4 assy up through 90 degrees to allow the bolts to be

inserted from underneath. (The counter balance arm needs to be removed

first). It does have the advantage that the castellated nuts and split pins

can be inserted from the front of TP4 and not tucked behind as in the TP14

assembly instructions.



Hope this answers some of you (good) questions.



Nigel (The other one)



--

wdaniell(at)etb.net.co
Guest

Posted: Mon Jun 25, 2007 8:32 am Post subject: Tailplane flutter

Hey bob can we talk off line so I can get a set  

Will  

         

  

From: owner-europa-list-server(at)matronics.com [mailto:owner-europa-list-server(at)matronics.com] On Behalf Of R.C.Harrison

 Sent: Sunday, June 24, 2007 09:31

 To: europa-list(at)matronics.com

 Subject: RE: Europa-List: 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  

  

   

--

kheindl(at)msn.com
Guest

Posted: Mon Jun 25, 2007 11:51 am Post subject: Tailplane flutter

Hi Nigel



Yes, thank you for the additional detail. Bt you still don't say HOW the TP4 

is to be cleaned out. And you say that the mass balance arm has to be 

disconnected. That means having to crawl into the tail section and 

performing all kinds of difficult tasks. My balance arm is very tight and 

that was easy to do with the top off. I don't really want to touch it. I am 

also not rushing into mod 70.

And as Mark and others have remarked: we don't really know anything about 

the accident. Except, that a wing landed on the road, the main fuselage in a 

field, that at least one tailplane came off initially, and a pip pin was 

bent 90 degrees. Obviously something started the chain of events from the 

tail somewhere. There may or may not have been any flutter. I guess we'll 

find out a bit more in a week or so.

I like the idea of doing away with the mass balance arm, and weighting the 

tailplanes internally, at least for new kits.



Karl





[quote]From: "Nigel Graham" <nigel_graham(at)btconnect.com>

Reply-To: europa-list(at)matronics.com

To: <europa-list(at)matronics.com>

Subject: RE: Tailplane flutter

Date: Mon, 25 Jun 2007 13:59:25 +0100




<nigel_graham(at)btconnect.com>



Hi Karl,



You're clearly thinking this through!



My description was only an abstract to give an idea of the concept.

The detailed proposals handle preparation insertion and bonding.



Here is a description for those of you with an enquiring mind - I will not

take offence if the rest of you skip this!



TP4 has to be de-greased and de-burred inside prior to insertion. The discs

have a scribe line on one side to indicate the orientation of the cross

drill (facilitating alignment). You were on the money with regard to the

insertion tool. A 6.0mm threaded bar (with two lock  nuts) screws into a

central hole in the disc. This allows the discs to be inserted into TP4 and

rotated into correct alignment - two from one side and two from the other.



The discs have a shallow groove centrally around the circumference. Once in

position, bearing grade anaerobic adhesive (Loctite) is introduced through

one of the TP4 holes and the discs rotated to distribute the adhesive. This

ensures concentricity and accommodates any small variance of inside

diameter.

An AN4 bolt can be temporally inserted to locate the disc in the correct

position and the thread bar removed. In this way, all four discs are placed

and bonded. The 6mm holes also serve to cross vent the tube and provide a

method (via spray tube) of introducing the anti-corrosion treatment of your

choice (ACF50, WD40, Shell "Ensis" fluid, granny's beef dripping) into TP4.



Once bonded, the tail can be re-assembled. The bolts have to be inserted

from the rear to guarantee clearance with the rear bulkhead. This will

involve rotating the TP4 assy up through 90 degrees to allow the bolts to 

be

inserted from underneath. (The counter balance arm needs to be removed

first). It does have the advantage that the castellated nuts and split pins

can be inserted from the front of TP4 and not tucked behind as in the TP14

assembly instructions.



Hope this answers some of you (good) questions.



Nigel (The other one)



--

grahamsingleton(at)btinte
Guest

Posted: Mon Jun 25, 2007 2:42 pm Post subject: Tailplane flutter

Remi

the clamp solution was Nigel Graham's not mine, but I do like it. I'm 

pleased your solution works too, my reservations about taper pins are 

about the risk of distorting the cross tube and causing binding in the 

bearings

regards

Graham



Rémi Guerner wrote:

[quote] Hi Graham,

 

  

 

 Sorry I missed your clamp solution. Anyway, I went the taper pin way. 

 Easy to do and very effective.

 

 Remi

 

  

 

 

 From: "R.C.Harrison" <ptag.dev(at)tiscali.co.uk 

 <mailto:ptag.dev(at)tiscali.co.uk>>

 Subject: 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

 

 --

grahamsingleton(at)btinte
Guest

Posted: Mon Jun 25, 2007 2:49 pm Post subject: Tailplane flutter

Don't think so Willie but I could be mistaken, only downside I can think 

of is a slight weight penalty.

Graham



William Harrison wrote:

 	  Quote: 	
		   

 <willie.harrison(at)tinyonline.co.uk>

 

 Nigel,

 

 Would there be any problem with doing this with 3/8 bolts on an  

 aircraft which had Mod 62 already done to it?

 

 This is such an appealing idea I think.

 

 Willie

fklein(at)orcasonline.com
Guest

Posted: Mon Jun 25, 2007 7:59 pm Post subject: Tailplane flutter

Nigel...very sweet (KISS) solution...one question: Why castellated nuts 

rather than nylocs?



Also.. What material(s) did you use for your "discs" and "saddles"?



Fred



On Monday, June 25, 2007, at 03:29  AM, Nigel Graham wrote:



 	  Quote: 	
		   To support the torque tube and prevent it distorting, 15mm wide

 cross-drilled discs are inserted into TP4 at each of the four stations.

 To spread the clamping load over a larger surface, "saddle blocks" 

 (profiled

 to mate with the OD of TP9 and TP12) are fitted under the bolt head and

 castellated nut.


	


-- 

This message has been scanned for viruses and

dangerous content by MailScanner, and is

believed to be clean.

carl(at)flyers.freeserve.
Guest

Posted: Mon Jun 25, 2007 11:54 pm Post subject: Tailplane Flutter

For what its worth, I believe the cause of this accident has nothing to do 

with "wear" in the tailplane assemblies. I base my "theory" on the simple 

fact that many Europas have flown many flying hours with no reported 

evidence of tailplane flutter.



Wear and tear is a fact of engineering life and the current Mod 62 seems to 

be as good a design as any.  Reports from the field suggest that with Mod 62 

done properly, subsequent wear is minimal.  Undoubtedly there are 

potentially better designs out there - hindsight is a wonderful thing.



My other concern is that changing a reasonably good design could move the 

problem elsewhere - how much damage is being done by builders kneeling in 

the back end of their fuselages - the push/ pull tube is very vunerable and 

simply cant be removed.



It seems more likely IMHO that there was a failure was due to the separation 

of one of the tailplanes for reasons which have already been discussed. 

Tailplane flutter may well have occurred when the tailplane disengaged the 

drive pins but this would not be attributable wear in the system. The PFA's 

current interest in the design of the pip pin recesses would lend weight to 

this possibility.



Till we have the full findings of the AIIB we shouldnt be redesigning the 

aeroplane based on such limited evidence (I know the PFA have asked for our 

feedback on this).



I would hope that before changing the design the PFA or Europa will conduct 

a survey amongst the current Europa fleet to establish if wear in the torque 

assembly (post Mod62) is a genuine problem or a myth. My understanding is 

that such a survey has not as yet been done - either by tha PFA or by the 

factory, though no doubt the recent sales figures of Mod 62 kits will give 

them a better idea.



Carl Pattinson

G-LABS

---

nigel_graham(at)btconnect
Guest

Posted: Tue Jun 26, 2007 12:35 am Post subject: Tailplane flutter

Hi Fred.



The castellated nut is a standard AN part and was chosen because the split

pins can be inspected visually at any time.

Nylocks would work perfectly - but there is no guarantee that somebody would

not re-use them and you cannot gauge the integrity by looking at them.



I specified zinc passivated mild steel for both on the grounds that the

coefficient of expansion is about the same as the TP4 and the risk of

galvanic action is reduced.

The truth is that you could probably make the discs out of an anodised alloy

with no ill effects - and save weight into the bargain.



Nigel



--

willie.harrison(at)tinyon
Guest

Posted: Tue Jun 26, 2007 1:04 am Post subject: Tailplane Flutter

Carl



Having flown around, at least for a short while, in a Europa with 1"  

of slop at the stab trailing edges (* see also below), without any  

sign of flutter, I tend to agree that slop of itself might not be a  

DIRECT cause of flutter in a Europa tailplane.   However, could it  

have been an INDIRECT cause: would you not agree that increasing  

"wear" in the TP12/TP4 joint could lead to a TP6 failure (via undue  

torsional loads going through the pip pin)? Having said that, I am  

aware that we are speculating about really happened and why, although  

some very strong hints are emerging already (PFA's invitation to us  

to propose anti-wear joint designs, and the focus on the pip pin recess)



* In my case, the slop was not due to wear but due to bad manufacture  

(he aircraft had total time of 12 hours when I bought it). If you can  

believe the paperwork, it had also been tested to Vne on two  

occasions in the previous 12 months when most or all of the 1" slop  

was present. Makes you think.



Willie



On 26 Jun 2007, at 08:53, Carl Pattinson wrote:



[quote] 

 <carl(at)flyers.freeserve.co.uk>



 For what its worth, I believe the cause of this accident has  

 nothing to do with "wear" in the tailplane assemblies. I base my  

 "theory" on the simple fact that many Europas have flown many  

 flying hours with no reported evidence of tailplane flutter.



 Wear and tear is a fact of engineering life and the current Mod 62  

 seems to be as good a design as any.  Reports from the field  

 suggest that with Mod 62 done properly, subsequent wear is  

 minimal.  Undoubtedly there are potentially better designs out  

 there - hindsight is a wonderful thing.



 My other concern is that changing a reasonably good design could  

 move the problem elsewhere - how much damage is being done by  

 builders kneeling in the back end of their fuselages - the push/  

 pull tube is very vunerable and simply cant be removed.



 It seems more likely IMHO that there was a failure was due to the  

 separation of one of the tailplanes for reasons which have already  

 been discussed. Tailplane flutter may well have occurred when the  

 tailplane disengaged the drive pins but this would not be  

 attributable wear in the system. The PFA's current interest in the  

 design of the pip pin recesses would lend weight to this possibility.



 Till we have the full findings of the AIIB we shouldnt be  

 redesigning the aeroplane based on such limited evidence (I know  

 the PFA have asked for our feedback on this).



 I would hope that before changing the design the PFA or Europa will  

 conduct a survey amongst the current Europa fleet to establish if  

 wear in the torque assembly (post Mod62) is a genuine problem or a  

 myth. My understanding is that such a survey has not as yet been  

 done - either by tha PFA or by the factory, though no doubt the  

 recent sales figures of Mod 62 kits will give them a better idea.



 Carl Pattinson

 G-LABS

 ---

carl(at)flyers.freeserve.
Guest

Posted: Tue Jun 26, 2007 2:09 am Post subject: Tailplane Flutter

Im not saying we shouldnt be concerned about the amount of slop in the 

tailplanes. The PFA's current limit of 1/2 inch would seem to be reasonable.



We checked ours last week - as soon as we recieved the PFA bulletins and 

found 3/8" movement between the tailplanes and a total of 5/8" movement when 

the counterbalance arm was locked against the top fuselage stop and both 

tailplanes moved up and down (hope that makes sense). Note - the second 

measurement is not a requirement of the original 1999 PFA bulletin though it 

goes on to say that no play is acceptable between TP04 an TP09.



We promptly installed Mod 62 and have concluded that the original 1/4" pins 

had probably always been a loose fit - either due to poor manufacture or 

installation. Unfortunately 13 years ago when we were building the aircraft 

we didnt understand the implications of loose fitting pins.



The aircraft had its annual in March and we did the dive to 150kts twice - 

once with Andy Draper at the controls and once with me. Im sure if anything 

had been amiss Andy would have noticed. We also did a series of stalls and 

incipient spins and again no problems were found.



One point I would mention is that there is no official Annual Inspection 

checklist for the Europa fuselage (as far as I am aware) and I believe this 

issue should be addressed. The current regime relies on the owner and 

inspectors vigilance in noticing defects and potential problems. Some 

inspectors will have more experience with Europa related issues and others 

less so.



And before anyone jumps to conclusions, I should make it clear that Andy 

Draper did not conduct the annual inspection - only the test flight. The 

annual inspection was none the less a thorough one.



So the business of tailplane flutter is a bit of a mystery.

---

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