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StructuraL failure or?

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josok-e(at)ukolo.fi
Guest

Posted: Tue Sep 11, 2007 6:25 am Post subject: StructuraL failure or?

Hi All,

As far as i know there is still no conclusion from the AAIB about the cause of this one and only structural failure. It keeps buzzing in my mind. It is a fact that there should be no slop in tail planes, that the bushes should be secure, and that wing pins should be properly attached. Period.

But was it the cause off the accident? Speed 90 knots, no abnormal movements, then suddenly very steep up and down movements, paper flying from the cabin. All according the AAIB report. 

I received the following suggestion, which i think has not been communicated before: The plane was rigged by three persons. What if one of the anti-trim tab drive pins was not in but on the T-rod? Everything would look pretty much OK, feel pretty much OK, until the pin would pass the T-rod, on which the anti tab would become a  pro-tab. This would cause a violent movement, on which the pilots correction would cause another and so on, until destruction. It would explain the described up and down movements eh? Start shooting please!



Regards,



Jos Okhuijsen

Visit -  www.EuropaOwners.org

gcrowder2

Joined: 09 Jan 2006
Posts: 136
Location: Golden, Colorado USA

Posted: Tue Sep 11, 2007 7:15 am Post subject: StructuraL failure or?

Also I've noticed that the T rod can be unthreaded by turning it over and over enough

 times to completely separate it from the drive mechanism if the nut is not tight.  What if this happened slowly over a period of years and finally came loose on that particular flight?  

   The trim position would be affected, but over time it might not be noticed.

  

                                                  Glenn 



 	  Quote: 	
		   Subject: StructuraL failure or?

 From: josok-e(at)ukolo.fi

 Date: Tue, 11 Sep 2007 17:23:02 +0300

 To: europa-list(at)matronics.com

 

 --> Europa-List message posted by: "josok" <josok-e(at)ukolo.fi>

 

 Hi All,

 As far as i know there is still no conclusion from the AAIB about the cause of this one and only structural failure. It keeps buzzing in my mind. It is a fact that there should be no slop in tail planes, that the bushes should be secure, and that wing pins should be properly attached. Period.

 But was it the cause off the accident? Speed 90 knots, no abnormal movements, then suddenly very steep up and down movements, paper flying from the cabin. All according the AAIB report. 

 I received the following suggestion, which i think has not been communicated before: The plane was rigged by three persons. What if one of the anti-trim tab drive pins was not in but on the T-rod? Everything would look pretty much OK, feel pretty much OK, until the pin would pass the T-rod, on which the anti tab would become a pro-tab. This would cause a violent movement, on which the pilots correction would cause another and so on, until destruction. It would explain the described up and down movements eh? Start shooting please!

 

 Regards,

 

 Jos Okhuijsen

 

 

 

 

 

 

 Visit - www.EuropaOwners.org

 

 



 

 

 


	


Make your little one a shining star! Shine on!  [quote][b]

josok-e(at)ukolo.fi
Guest

Posted: Tue Sep 11, 2007 8:01 am Post subject: StructuraL failure or?

Hi Glenn 

No, the T bar can not turn, because there should be a lock nut on the thread. But it's perfectly possible to rig a trim tab wrong, at least on one side. It's not obvious on quick visual inspection. Only moving the tabs  by hand one at a time does make sure that they are engaged properly. 



Regards,



Jos Okhuijsen

Visit -  www.EuropaOwners.org

gcrowder2

Joined: 09 Jan 2006
Posts: 136
Location: Golden, Colorado USA

Posted: Tue Sep 11, 2007 9:32 am Post subject: StructuraL failure or?

Hi Josok - well mine turns and it's probably not the only one!

  

                                             Glenn



 	  Quote: 	
		   Subject: Re: Europa-List: StructuraL failure or?

 From: josok-e(at)ukolo.fi

 Date: Tue, 11 Sep 2007 18:59:35 +0300

 To: europa-list(at)matronics.com

 

 --> Europa-List message posted by: "josok" <josok-e(at)ukolo.fi>

 

 Hi Glenn 

 No, the T bar can not turn, because there should be a lock nut on the thread. But it's perfectly possible to rig a trim tab wrong, at least on one side. It's not obvious on quick visual inspection. Only moving the tabs by hand one at a time does make sure that they are engaged properly. 

 

 Regards,

 

 Jos Okhuijsen

 

 

 

 

 

 

 Visit - www.EuropaOwners.org

 

 

 

 

 

&=======================
	


&g=================

 	  Quote: 	
		   

 

 


	


Kick back and relax with hot games and cool activities at the Messenger Café. Play now!  [quote][b]

josok-e(at)ukolo.fi
Guest

Posted: Tue Sep 11, 2007 10:12 am Post subject: StructuraL failure or?

Hi Glenn, 



Good that you noticed, now please check the Manual, chapter 19 page 6, and find the lock nut that you forgot. Better late and in time then another addition to the statistics.



Regards,



Jos Okhguijsen

Visit -  www.EuropaOwners.org

carl(at)flyers.freeserve.
Guest

Posted: Tue Sep 11, 2007 1:11 pm Post subject: StructuraL failure or?

Please be assured you would know if you attempted a takeoff with the T bar 

disconnected - I have done it !!!!



On commencing the takeoff run the stick was VERY back heavy such that when I 

started to ease the stick forwards I assumed the controls were jammed and 

aborted the takeoff. Gravity makes the trim tabs hang down forcing the 

trailing edge of the tailplanes upwards. As this is the normal position for 

takeoff (stick hard back till airspeed is reached), the problem dosent 

become obvious till the pilot tries to move the stick forward in order to 

raise the tailplane. Believe me it isnt something you could miss.



If only one of the pins was engaged this would disengage fairly rapidly. 

Even if this didnt occurr there would still be a substantial force acting on 

the disengaged tailplane which would be hard to miss. It is unlikely that 

this could be trimmed out using the trim servo.



Carl Pattinson

G-LABS



---

josok-e(at)ukolo.fi
Guest

Posted: Tue Sep 11, 2007 2:17 pm Post subject: StructuraL failure or?

Hi Carl

Thanks for your observations.

My question was, what happens if one pin was engaged, and the other one rests on top of the T bar. 

It is possible to (mis)rig that way. The other pin will hold, because like many, i have a board with a slot just to keep the bar centered. 

Would it go unnoticed until the loose pin would pass the bar? Would it tear the plane apart because of the reverse reactions it would cause?



Regards,



Jos Okhuijsen

Visit -  www.EuropaOwners.org

ami(at)mcfadyean.freeserv
Guest

Posted: Wed Sep 12, 2007 1:41 pm Post subject: StructuraL failure or?

On the other hand, I have had one of the little plastic bushes in the T-bar 

fall out during derigging, although this was spotted before the next flight. 

But what could have been the consequence had it not been spotted?



Duncan Mcf.

---

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

Posted: Wed Sep 12, 2007 2:48 pm Post subject: StructuraL failure or?

All 

I believe Roger Bull had an incident with the servo trim tabs which

resulted in the modification which stiffened the drive pin plates.



Perhaps he would kindly contribute to this thread?



When I had my trim motor "failing to reverse" without going to full

travel position problem, the forces on the control stick were enormous

to such a degree I allowed the plane to climb momentarily until it

reached full trim nose up position before reversing the mode of

operation.  I would have had great difficulty landing in this

configuration in fact I doubt it possible. 

Regards

Bob H.



--

josok-e(at)ukolo.fi
Guest

Posted: Thu Sep 13, 2007 5:45 am Post subject: StructuraL failure or?

Hi Bob,



Yes, i noticed the enormous effect of the trim-tabs.

Trim to the limits at cruise was one of the items in the test program for my plane. And, exactly as in your experience, the forces, especially for the nose-up situation, were so much, that i was afraid something would break. 



The experience changed my opinion about the danger of the your out-of-control trim motor story, which i clearly remember. 

I have now a clear marking next to the pullable circuit breaker for the trim system, on the panel and in my mind, should this ever happen. 



Now i am writing this, i realize that the other action would be to slow down the plane, it would probably lower the stick forces to a manageable level as well. To be checked!



Still waiting for opinions on the one not-connected trim-tab leading to destruction scenario though!

Visit -  www.EuropaOwners.org

keithhickling(at)clear.ne
Guest

Posted: Thu Sep 13, 2007 11:15 pm Post subject: StructuraL failure or?

Jos,

I don't understand why you are suggesting that if one drive pin is not 

connected to the T bar, the anti-servo tabs would function in reverse (ie 

causing positive instead of negative feedback to tailplane movement, so 

causing instability. I don't see why the unconnected one should move in 

reverse direction. Can you explain your thoughts in more detail?



Regards,

Keith.

New Zealand.



---

josok-e(at)ukolo.fi
Guest

Posted: Fri Sep 14, 2007 1:42 am Post subject: StructuraL failure or?

Hi Keith,

Thanks for making clear that it is not so obvious.  Let me try again, in as much detail as i can think of. 

While rigging the tail planes, it is possible to have one anti-trim-tab drive pin on top of the TS05 t-bar instead of in. Once that is done, it will be difficult to see the difference. Gravity will keep the pin on top, there is no room for the pin to fall past the t-bar. The pitch control system will work, the trim tabs will move up and down just like in the proper rigging situ. 

Now we go flying. Everything will seem fine. Then, some turbulence or input force on the pitch trim system forces the trim tab drive pin past, down of the t-bar. The trim tab will now be pointing downwards of the original position. Remember, these are anti-trim tabs, so not only the trim will way off, but also the feed-back is wrong, opposite of what the pilot would expect. That's what i mean be reverse effect. So the nose is going down, and the force on the stick is up! As we know, the all moving tail pitch control is very powerful. Imagine you are happy flying along, maybe with a little bit of back pressure on the stick, and all of a sudden the stick wants to move backwards, and the plane pitches sharp UP. The first reaction will be to control the stick, which, because of the error in the pitch control and the lack of anti forces, will cause awesome forces, lots of G´s. The next input will be opposite, and IMHO could start breaking things apart. The lack of anti-forces, tog

 ether with the trim badly off track will cause a Pilot Induced Oscillation way beyond what ever could happen with a connected anti-trim-tab.

Well, that's the theory, and folks, please try to put it to rest. 



Regards,



Jos Okhuijsen

Visit -  www.EuropaOwners.org

jonsmitheuropa(at)tiscali
Guest

Posted: Sun Sep 16, 2007 12:00 am Post subject: StructuraL failure or?

Hi, Just a couple more points on this topic!  Two years ago a friend of mine with his owner/build partner flew with one trim tab's pin disengaged (for 200 nm to the PFA Kemble rally infact!) and they didn't notice any difference!  Neither were very experienced on the Europa at the time though having only recently finished it.  My friend (his turn to fly home) noticed it on his preflight walk around at Kemble.



I think they were both very lucky.  Yesterday, as a result of this topic, when I was at my plane I deliberately "accidently" rigged the tailplanes with a pin disengaged, to see what happens to the tab and T-bar.  I started with the pin resting on top of the T-bar.  On mine the pin sits naturally on top of the bar towards the rear of it.  On moving the elevator control the pin can very easily drop to beneath the bar and does so readily.   Personally I don't think this would have an enormous aerodynamic effect, the tab is very light and I think it would just stream with the airflow if it's not fixed to the actuating mechanism (my uneducated opinion) [b:57be851a4b]BUT, what I did notice was that with the pin below the T-bar, when I moved the stick fully back the pin was able to drop a bit lower and lodge on top of that funny fuselage joggle/ moulding that sticks out from the fuselage vertically parallel to the T-bar slot, very effectively jamming the elevator almost fully up.[/b

 :57be851a4b]  On mine it did it every time I tried it and was impossible to free from the cockpit.

Easy solution - do not fly a mis-rigged aeroplane!

Cheers, Jon

Visit -  www.EuropaOwners.org

fklein(at)orcasonline.com
Guest

Posted: Sun Sep 16, 2007 8:47 am Post subject: StructuraL failure or?

On Sunday, September 16, 2007, at 12:57  AM, JonSmith wrote:



 	  Quote: 	
		   Yesterday, as a result of this topic, when I was at my plane I 

 deliberately "accidently" rigged the tailplanes with a pin disengaged, 

 to see what happens to the tab and T-bar.  I started with the pin 

 resting on top of the T-bar.  On mine the pin sits naturally on top of 

 the bar towards the rear of it.  On moving the elevator control the 

 pin can very easily drop to beneath the bar and does so readily.


	


 	  Quote: 	
		   BUT, what I did notice was that with the pin below the T-bar, when I 

 moved the stick fully back the pin was able to drop a bit lower and 

 lodge on top of that funny fuselage joggle/ moulding that sticks out 

 from the fuselage vertically parallel to the T-bar slot, very 

 effectively jamming the elevator almost fully up.[/b:57be851a4b]


	


 	  Quote: 	
		   On mine it did it every time I tried it and was impossible to free 

 from the cockpit.


	


Jon...thanks for taking the time to check this out (safely on the 

ground). Coupled with Jos's hypothesis and the radar tracking data he 

referenced in his posts of Sept. 11 and Sept. 14, this is beginning to 

sound like a plausible scenario. I hope someone is forwarding it to the 

AAIB.



Fred

A194

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willie.harrison(at)tinyon
Guest

Posted: Sun Sep 16, 2007 9:14 am Post subject: StructuraL failure or?

In addition to the radar tracking data I understand (don't know if it  

is rumour or established fact) that the investigators have  

interrogated the aircraft's gps and found evidence of much higher  

speed than previously assumed. Can anyone shed light on this?



Willie H.

rparigor(at)suffolk.lib.n
Guest

Posted: Sun Sep 16, 2007 9:26 am Post subject: StructuraL failure or?

For what it is worth, I attached a copy of Mod 58 which describes

handeling of Europa in flight with a fractured trim tab drive pin.



Ron parigoris

carl(at)flyers.freeserve.
Guest

Posted: Sun Sep 16, 2007 11:28 am Post subject: StructuraL failure or?

The aircraft had just been through its annual inspection at Bodmin (where 

the aircraft had flown to). My understanding is that the post inspection 

flight test may have taken place during the course of the return flight.



This would have included a dive to VNE (ie: 165 kts). If the recovery was 

made badly the airframe could have become overstressed, resulting in 

premature failure of one or both of the wings.



It is already public knowledge that one of the wing root pins was badly 

installed resulting in the pin ripping out from the alloy mounting plates in 

the wing root.



However this is only a theory and we may never know what caused this tragic 

accident.



Carl Pattinson



---

fklein(at)orcasonline.com
Guest

Posted: Sun Sep 16, 2007 1:17 pm Post subject: StructuraL failure or?

On Sunday, September 16, 2007, at 12:27  PM, Carl Pattinson wrote:



 	  Quote: 	
		   It is already public knowledge that one of the wing root pins was 

 badly installed resulting in the pin ripping out from the alloy 

 mounting plates in the wing root.



 However this is only a theory and we may never know what caused this 

 tragic accident.


	


As Carl implies, the key question is: What was the initiating event?



Fred



do not archive

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willie.harrison(at)tinyon
Guest

Posted: Sun Sep 16, 2007 1:26 pm Post subject: StructuraL failure or?

....or if the air was not smooth at vne???



On 16 Sep 2007, at 20:27, Carl Pattinson wrote:



 	  Quote: 	
		   

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



 The aircraft had just been through its annual inspection at Bodmin  

 (where the aircraft had flown to). My understanding is that the  

 post inspection flight test may have taken place during the course  

 of the return flight.



 This would have included a dive to VNE (ie: 165 kts). If the  

 recovery was made badly the airframe could have become  

 overstressed, resulting in premature failure of one or both of the  

 wings.



 I

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