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British testing

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yak52

Joined: 25 Oct 2007
Posts: 50

Posted: Tue Jun 16, 2009 11:12 am Post subject: British testing

The following might be of interest to you. This is the reply from the LAA to my inquiry about the  purposes and parameters of the upcoming testing.  

  

  

 "If I may expand very briefly.  Firstly, there have been no cases of wing failure in the UK involving 601XL aircraft, there has been a failure of the three piece wing which lead to discussions about the light stick force per g.  This failure was a clear overload failure and (I appreciate that it is impossible to be 100% sure) evidence from witnesses suggest strongly that the pilot ‘pulled the wings off’.  Clearly we are not happy that this can happen and other (worldwide) failures appear to point to two principle areas of concern; 1. pilot training for sport type aircraft and 2. the low stick force per g.  We will be making recommendations about light pitch control forces, based on experience gained with this incident, when we issue the mod kit to update XL’s.  

  

When the AD grounding the CH 601 XL was issued in Holland we discussed whether we should follow suit, we decided not to do this as it was effectively an unknown machine operating within a completely different regulatory environment.  We were quite surprised when Zenair Europe published a Factory AD requiring ‘validation’ of the control cable tensions because, at low tensions, flutter had been reported.  As you may know we recommended that the aircraft be grounded on the strength of this.  

  

As an organisation we decided to do a re-validation exercise on the primary structure and found one or two areas that we were not happy with, hence the wing mods.  What we have never said is that the aircraft is not strong enough, only that it doesn’t meet our requirements fully in some areas.  We have never connected the structural failures reported worldwide with the UK grounding, because they are not connected.  The LAA  system for Permit aircraft is, whilst slower than some entrepreneur’s would like, very robust.  I say all this because we are certainly not going to fly the aircraft to different loads until it breaks, we can find this braking point with a pen and paper, and, we know that the mass balance will prevent aileron flutter (even at light cable tensions), so we don’t need a ‘baseline’ here.

  

As soon as the aircraft is successfully test flown we will approve the mod kit and start the process of getting chaps back in the air.  It will be up to others to determine reasons for other accidents worldwide."

  [quote][b]

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psm(at)att.net
Guest

Posted: Tue Jun 16, 2009 5:35 pm Post subject: British testing

Hi Roger,



 Thank you for posting the LAA comments on the UK handling of the Zodiac XL.



 I hope the mods approved by the LAA will be distributed so the rest of us can install them.  I don't know if it is appropriate for the mods to be distributed without a fee or if a fee would be appropriate.  I don't really care if there is a modest fee.



 I have grounded my XL waiting for properly engineered design changes to satisfy the NTSB ruling.  In particular I want aileron mass balance and some redesign to eliminate the stick force per G issues.  I would prefer if the changes were analyzed by Chris or one of his representative engineers, but perhaps the LAA changes already have met that burden.  The only question remaining in my mind is whether or not the UK XL version is close enough to my own (standard Zenith kit) so the analysis is valid.



 Paul

 XL grounded



 

 At 11:59 AM 6/16/2009, you wrote:

 [quote]The following might be of interest to you. This is the reply from the LAA to my inquiry about the  purposes and parameters of the upcoming testing.  

  

  

 "If I may expand very briefly.  Firstly, there have been no cases of wing failure in the UK involving 601XL aircraft, there has been a failure of the three piece wing which lead to discussions about the light stick force per g.  This failure was a clear overload failure and (I appreciate that it is impossible to be 100% sure) evidence from witnesses suggest strongly that the pilot ‘pulled the wings off’.  Clearly we are not happy that this can happen and other (worldwide) failures appear to point to two principle areas of concern; 1. pilot training for sport type aircraft and 2. the low stick force per g.  We will be making recommendations about light pitch control forces, based on experience gained with this incident, when we issue the mod kit to update XL’s.  

  

 When the AD grounding the CH 601 XL was issued in Holland we discussed whether we should follow suit, we decided not to do this as it was effectively an unknown machine operating within a completely different regulatory environment.  We were quite surprised when Zenair Europe published a Factory AD requiring ‘validation’ of the control cable tensions because, at low tensions, flutter had been reported.  As you may know we recommended that the aircraft be grounded on the strength of this.  

  

 As an organisation we decided to do a re-validation exercise on the primary structure and found one or two areas that we were not happy with, hence the wing mods.  What we have never said is that the aircraft is not strong enough, only that it doesn’t meet our requirements fully in some areas.  We have never connected the structural failures reported worldwide with the UK grounding, because they are not connected.  The LAA  system for Permit aircraft is, whilst slower than some entrepreneur’s would like, very robust.  I say all this because we are certainly not going to fly the aircraft to different loads until it breaks, we can find this braking point with a pen and paper, and, we know that the mass balance will prevent aileron flutter (even at light cable tensions), so we don’t need a ‘baseline’ here.

  

 As soon as the aircraft is successfully test flown we will approve the mod kit and start the process of getting chaps back in the air.  It will be up to others to determine reasons for other accidents worldwide."



  	  Quote: 	
		  

[/b] 	
[b]

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jonaburns

Joined: 23 May 2007
Posts: 32

Posted: Tue Jun 16, 2009 6:48 pm Post subject: Re: British testing

Paul,



You say:  "I have grounded my XL waiting for properly engineered design changes to satisfy the NTSB ruling."



You have not grounded anything, you have abandoned it.  You have a kit that YOU have chosen NOT to complete, just like thousands of builders of different manufacturers.  



My brother has a float plane kit he started 15 years ago.  The fiberglass boat is delaminated, so I guess he should call it "grounded" too.



Your choice of words, along with your attitude towards those that do fly safely is the main problem we have here.



Using your logic, my kids have a grounded time machine in their bedroom and a grounded spaceship out back.   



Jon Burns

Little Elm, TX

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psm(at)att.net
Guest

Posted: Tue Jun 16, 2009 7:12 pm Post subject: British testing

Dear Jon,



You are simply full of shit.



You have no concept what I might have or not have.  To support such a 

statement as you have made you would need either godlike powers or 

keys to my hangar.



I don't know why you would want to attack my situation in such a 

personal and offensive way, but I suggest you consider making such 

comments in a private channel and checking your facts before making a 

public spectacle of yourself.



I do not have a kit.  I have a finished airplane.  It is registered 

with the FAA registry (N773PM).  It was about to be inspected for 

airworthiness within a few days of the NTSB ruling.  When the ruling 

came out I spent a couple of days considering all the details and 

discussing them with my wife (who is also an aviator).  We decided 

the only reasonable choice was to ground the plane until the issues 

raised by the NTSB were resolved.



I do not suggest that anyone should follow my lead and ground their 

own planes.  I never have.  This is a decision each owner must make 

for himself.  Of course this freedom doesn't extend to the many 

owners in the UK, Netherlands, and Germany where the government has 

grounded their planes for them.



I have not abandoned anything - except perhaps for my faith in the 

reasonableness of some members of this email discussion group.  My XL 

is still in my hangar awaiting resolution of the issues raised by the NTSB.



I can understand small minded people who feel a need to attack others 

who don't agree with them.  I do not consider this acceptable behavior.



I fully expect an apology, in the same public media as your foolish 

accusation, for your outrageous and unsupportable comments.



Paul

XL grounded

At 07:48 PM 6/16/2009, you wrote:



 	  Quote: 	
		  Paul,



You say:  "I have grounded my XL waiting for properly engineered 

design changes to satisfy the NTSB ruling."



You have not grounded anything, you have abandoned it.  You have a 

kit that YOU have chosen NOT to complete, just like thousands of 

builders of different manufacturers.



My brother has a float plane kit he started 15 years ago.  The 

fiberglass boat is delaminated, so I guess he should call it "grounded" too.



Your choice of words, along with your attitude towards those that do 

fly safely is the main problem we have here.



Using your logic, my kids have a grounded time machine in their 

bedroom and a grounded spaceship out back.



Jon Burns

Little Elm, TX

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jonaburns

Joined: 23 May 2007
Posts: 32

Posted: Tue Jun 16, 2009 7:42 pm Post subject: Re: British testing

Paul,



You made a post a few days ago stating your plane is not complete.  You said it would be 2 or so weeks more work.   You state here that it has not been inspected, thus you still have a kit.  



I will not apologize here or anywhere.  Your have not completed the kit, you do not have an airworthiness certificate, therefore you couldn't fly even if you want to... which you do not.   Calling it grounded is a misnomer.  



AGAIN, you cannot ground that which cannot fly.



Jon Burns

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rene(at)felker.com
Guest

Posted: Tue Jun 16, 2009 8:06 pm Post subject: British testing

I have been a lurker on this list for a couple of months and I am shocked at

the discourse.  I have been trying to convince my wife to let me build a

Zenith and have been gathering data, etc.  And, had to suffer through all

this ?????? (whatever you want to call it) trying to form an opinion about

the Zenith products.  I am looking at the 750, but would not build one if I

was not confident in the company.



I also participate in other lists and just can not believe the attacks that

go on here.  Paul, I understand your point about your decision to ??ground

your kit, but why attack Jon over the definition of whether or not your

project is airplane.  Does it matter, no.  And Jon, why the sideways attack

of Paul by trying to define his aircraft as just an abandoned project...it

does not add anything to topic, just looks like an attempt to

inflame....that worked



Here are my options......flame away.



The 601 has some unexplained crashes and it is important to try and find the

reason.



A lot of people are pointing fingers at root causes that they have no

evidence or proof for. E.g flutter



The law of unintended consequences should be understood...what will a 5

pound weight do to the aileron?  The wing......be careful not to create one

problem trying to fix another....



We had an accident here in Utah last year, I don't think I would have flown

that day......I think they were forecasting 30 knots winds from the south,

when I heard about the crash and saw it on the news I was not totally

surprised.  With winds that strong, flight in the leeward side of the

mountains can be very tough...



I am still going to keep monitoring this and other list and just ignore the

hostile post.



Rene'

801-721-6080

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