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jfowler120(at)verizon.net
Guest

Posted: Wed Oct 28, 2009 7:28 am Post subject: Flying Times

N156WT (Williamsburg, VA with 4 owners) does about  140 hours per year.

 [quote]   ---

johnd

Joined: 09 Jun 2009
Posts: 27

Posted: Wed Oct 28, 2009 7:45 am Post subject: Flying Times

N601JD in Spruce Pine, NC, I've gotten 32 hours since my first flight in Jan. Would have had more but the wx has been crummy this year...

 

 John Davis

 

 BobbyPaulk(at)comcast.net (BobbyPaulk(at)comcast.net) wrote: [quote]   p { margin: 0; }   Guys   

 can we get a show of hands on who is flying and how much. i would have done much more except for weather and runway construction. went to a fly-in 100 miles away. good time, good food. indicated 125 mph at 5500' with a 155 mph ground speed

 hopefully we are getting better weather. 

   

 N131BP

 601 XL E-AB

 14hrs since June

   

    	  Quote: 	
		  



 href="http://www.matronics.com/Navigator?Zenith601-List">http://www.matronics.com/Navigator?Zenith601-List

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

 href="http://www.matronics.com/contribution">http://www.matronics.com/contribution



	
 [b]

mhubel

Joined: 05 Sep 2009
Posts: 141

Posted: Wed Oct 28, 2009 7:55 am Post subject: Re: Flying Times

N708HU FIT, MA have 32 hours since first flight. Like others, weather and fighting with Bing have reduced the total.

_________________
Mark Hubelbank
N708HU
CH601XL
Jabiru 3300
Rotec TBI 40-3 carb
Sensenich ground adj prop.
240 hr TAF
Pictures at photo.hubbles.com

DaveG601XL

Joined: 27 Oct 2006
Posts: 351
Location: Cincinnati, Oh

Posted: Wed Oct 28, 2009 7:59 am Post subject: Re: Flying Times

I flew about 70 hours this year and have 115 total hours now.  Made x-country trips to Oshkosh once and to Illinois three times.  Hit about 15 fly-ins and pancake breakfasts.  This week I flew at night for the first time and got enough takeoff's and landings to become night current.  I have no qualms about flying the 601XL, even at night.



p.s. since we have had recent discussions about nose gear, my experience with a light engine (Jabiru) and the gear turned around (flat face forward), is that I can typically hold the nose gear off for about 5 seconds before it eases down. It required some technique refining, but not a lot.  



Footloose and flutter free,

SWORFI09_35.jpg

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_________________
David Gallagher
Cincinnati, OH area

bryanmmartin

Joined: 10 Jan 2006
Posts: 1018

Posted: Wed Oct 28, 2009 8:08 am Post subject: Flying Times

52 hours over the past twelve months out of Ray, MI.

BobbyPaulk(at)comcast.net wrote:

 	  Quote: 	
		   Guys

 can we get a show of hands on who is flying and how much. i would  

 have done much more except for weather and runway construction. went  

 to a fly-in 100 miles away. good time, good food. indicated 125 mph  

 at 5500' with a 155 mph ground speed

 hopefully we are getting better weather.




	


-- 

Bryan Martin

N61BM, CH 601 XL,

RAM Subaru, Stratus redrive.

do not archive.

_________________
--
Bryan Martin
N61BM, CH 601 XL, Stratus Subaru.
do not archive.

Doug.Norman(at)sportaviat
Guest

Posted: Wed Oct 28, 2009 8:37 am Post subject: Flying Times

172 hrs personal flying so far this year on the Zodiac; 468 total. No

Stephen Smith trips, but regularly back and forth between north Georgia and

Clearwater, FL. And often back and forth between Clearwater and Boca Raton,

FL (visiting kids). Only issue (since taking it off the rental line - whole

other story there) was an oil leak in a valve cover (Continental O-200); and

a cracked canopy from having it slam down onto a headset from a gust of wind

- take note folks. Nothing with the airframe. 



Doug Norman, CFI, AGI

N601DN



--

yak52

Joined: 25 Oct 2007
Posts: 50

Posted: Wed Oct 28, 2009 10:12 am Post subject: Flying times

Approximately 90 hrs/year. 220 in total on this airframe. The real question is: how many of you have stopped flying the airplane because of this "flutter" mess. The nay-sayers are of the opinion that only a few people are flying, and they're in the majority with their decision not to fly.  I don't see anyone on ZenithAero having made that decision, and no, I don't include those don't have a finished airplane and spend their days wringing their hands and looking for another reason not to complete.  [quote][b]

psm(at)att.net
Guest

Posted: Wed Oct 28, 2009 10:48 am Post subject: Flying times

Hi Roger,



 I hope you are not including me in the "nay-sayers of the opinion that only a few people are flying" but I suspect this is indeed your interpretation.  I also object to your characterization of the problems with the Zodiac XL as "Flutter" mess.  Let me try to clear up my own position.



 Flutter never was a serious likelihood to explain the XL problems.  Indeed, the problems are a considerable number of fatal in-flight structural failures in the last few years.  I don't know the exact number of these events but I think it is somewhere between 5 and 10 worldwide.



 As to the number of grounded XLs, my belief is that nobody knows the answer to this question.  There is no official registry of flights world-wide to give a definitive answer.  We all know that several countries in Europe have grounded the XL and that one of them, the UK, has released a long list of changes that will enable owners in that country to resume flights.  As far as I know the other countries still have the XLs grounded.



 I appreciate the idea of having list members announce their own recent flight records.  This is a haphazard way to determine how many planes are flying vs. grounded, but it is the best one I have heard of yet.



 So far I have counted around 8 owners who replied that they are still flying their XLs.  For reference, the 2008 Kitplanes lists the number of completed and flying XLs as 950.  I don't know how to interpret these related numbers, but it does seem only a few are still flying.  Of course the number of responses is only a small percentage of the number actually in use.  This is a limited, but large, email list of Zodiac builders and owners, and I am sure there are a number of owners flying that have not responded.  Several list members have made it clear they are flying and have not responded to this query.



 If only 10 percent of the flying Zodiac XL owners have responded and the Kitplanes number is reasonably accurate that would suggest 90 percent of the fleet is grounded.  This doesn't surprise me since the NTSB asked for this result and indeed several countries (not including the USA) have responded with regulatory force on the subject.  



 Still, I am not sure of the real numbers, and I don't even think this really matters.  My position always has been that we don't need a consensus on this issue.  It is a decision each owner should make according to his own judgement and situation.  It is only a few very vocal folks still flying their Zodiac XLs that seem to want a justification for their choice by citing numbers of people who agree with them.  



 My own position since the NTSB letter has been, and remains, my plane is grounded until we get a formal release of engineering changes from Chris Heintz or one of his related companies to resolve this problem.  That change has been promised to me by Sebastian Heintz as coming "Soon".  I have no idea when his promise will be filled, but I will wait for it.  I don't know why it seems to annoy some people so much that I have chosen this path, but apparently it does.



 Paul

 XL awaiting engineering changes



 

 At 11:06 AM 10/28/2009, you wrote:



 [quote]Approximately 90 hrs/year. 220 in total on this airframe. The real question is: how many of you have stopped flying the airplane because of this "flutter" mess. The nay-sayers are of the opinion that only a few people are flying, and they're in the majority with their decision not to fly.  I don't see anyone on ZenithAero having made that decision, and no, I don't include those don't have a finished airplane and spend their days wringing their hands and looking for another reason not to complete. 

  	  Quote: 	
		  

[/b] 	
[b]

zjohnson(at)ucnsb.net
Guest

Posted: Wed Oct 28, 2009 10:51 am Post subject: Flying Times

Add my 2 cents worth..672 hrs total..CH601HDS.NSI subaru



 Jackie Johnson  N5JZ

--- bryanmmartin(at)comcast.net wrote:



From: Bryan Martin <bryanmmartin(at)comcast.net>

To: zenith601-list(at)matronics.com

Subject: Re: Flying Times

Date: Wed, 28 Oct 2009 12:05:57 -0400






52 hours over the past twelve months out of Ray, MI.

BobbyPaulk(at)comcast.net wrote:

 	  Quote: 	
		   Guys

 can we get a show of hands on who is flying and how much. i would  

 have done much more except for weather and runway construction. went  

 to a fly-in 100 miles away. good time, good food. indicated 125 mph  

 at 5500' with a 155 mph ground speed

 hopefully we are getting better weather.




	


-- 

Bryan Martin

N61BM, CH 601 XL,

RAM Subaru, Stratus redrive.

do not archive.

jfowler120(at)verizon.net
Guest

Posted: Wed Oct 28, 2009 11:08 am Post subject: Flying times

Rubbish.

  

 Karl

 [quote]   ---

Doug.Norman(at)sportaviat
Guest

Posted: Wed Oct 28, 2009 1:39 pm Post subject: Flying times

Paul’s right that nobody knows the actual number of “grounded” 601s, or those “still flying.” And there are some weak arguments offered which claim some statistical backup for what one might conclude. He’s also correct that this isn’t a consensus activity.   

   

If one could gather data on a reasonable sample of people who have XLs, and mine their experiences, then one could apply simple non-parametric statistics and get a handle on what the likely status is.  

   

So… I took a couple of hours and went on the Zenith.Aero site to gather what data there might be. I went and pulled the member data from the site for all the 601 XLs which are flying in the US. I then divided them into four categories:   

<![if !supportLists]>1)      <![endif]>Those who list themselves as “flying,” but there’s not enough data to put them clearly into flying or not flying (as determined by there being no activity on the site. They registered, described themselves, but no other data is there to conclude whether they are actually flying or not).  

<![if !supportLists]>2)      <![endif]>Those who are clearly flying as determined by pictures, discussions with others, etc.  

<![if !supportLists]>3)      <![endif]>Those who list themselves as flying, but are explicit about keeping themselves on the ground, or where one can reasonably infer that they are not flying  

<![if !supportLists]>4)      <![endif]>Those who register as “other” and who might have changed their listing from “flying” based on them grounding themselves.  

   

Remember, these are only for those people who have registered on the site. The details are below for those who want to check my math.  

   

The results are clear: people, as a rule, are not grounding themselves. The explanation for the continuing belief that they are grounding themselves must be due to those who are asserting this without any data to support their contention. In fact I wasn’t able to find a single example of someone who had voluntarily grounded themselves on the site. But we know they exist. Paul is one. Therefore, they must represent a small slice of the owners/operators of Xls. Essentially, statistically insignificant (yet loud with assertions).  

   

This invalidates a number of assertions I’ve seen which suggest that the reason there are few additional episodes is probably due to the lack of flight hours. Sorry, that suggestion is not supportable.  

   

The most likely explanation is that people are flying within the limits of the airplane in a reasonable, responsible manner. And, isn’t that what everyone should do at all times? Fly your airplanes and enjoy them.  

   

----------------------------------------------------------  

Here are the results:  

   

<![if !supportLists]>-          <![endif]>Total 601 XLs Flying in the US:     92  

<![if !supportLists]>-          <![endif]>“Flying” but indeterminate:         32  

<![if !supportLists]>-          <![endif]>“Flying” and flying:                          60  

<![if !supportLists]>-          <![endif]>“Flying” but grounded:                   0  

<![if !supportLists]>-          <![endif]>“Other” and grounded:                  0  

   

We now have sufficient data to test a number of hypotheses  

---------------------------------------------------  

Hypothesis 1: “90% of the fleet are voluntarily grounded”  

   

To allow the best possibility of this, we’ll assign all “Flying but indeterminate” to the “voluntarily grounded” category.  

Now we’ll perform a Chi Square in the following way:  

                Flying:   

Observed: 60     Expected: 9        (10% of 92)  

                Grounded:  

                                Observed: 32     Expected: 83     (90% of 92)  

   

Chi Square = 0.0001         Thus, this hypothesis is exceedingly unlikely, and we reject it.  

-------------------------------------------------------  

   

Hypothesis 2: “50% of the fleet are voluntarily grounded”  

   

Again, to allow for the reading of the data which would most support this possibility we assign all “Flying but indeterminate” to the “voluntarily grounded category”  

   

                Flying:  

                                Observed: 60     Expected: 46  

                Grounded:  

                                Observed: 32     Expected: 46  

   

Chi Square = 0.0035         Thus, as before, we reject the hypothesis  

-----------------------------------------------------------------  

   

Hypothesis 3: “Everybody is flying”  

   

                Flying:  

                                Observed: 60     Expected: 91  

                Grounded:  

                                Observed: 32     Expected: 1  

   

Chi Square = 0.0001         Thus this must be rejected too. Thus, because we can’t assign the indeterminate category, we can’t make this statement either.  

                  

It turns out the largest supportable global distribution of voluntarily grounded aircraft  turns out to be about 20% IF you assume ALL indeterminates are voluntary groundings. This is probably not correct; thus, one might conclude that, among the Zenith.Aero community, there are few voluntary groundings.   

   

I suspect that, since there were NO explicit statements of voluntary grounding, they probably are pretty rare.  

   

Thus, fleet-hours are being accumulated at a rate consistent with what one would expect absent this unfortunate set of issues.   

       

From: owner-zenith601-list-server(at)matronics.com [mailto:owner-zenith601-list-server(at)matronics.com] On Behalf Of KARL POLIFKA

 Sent: Wednesday, October 28, 2009 3:08 PM

 To: zenith601-list(at)matronics.com

 Subject: Re: Flying times  

  

  

     

Rubbish.  

    

   

    

Karl  

   	  Quote: 	
		      

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

    

From: Paul Mulwitz (psm(at)att.net)   

    

To: zenith601-list(at)matronics.com (zenith601-list(at)matronics.com)   

    

Sent: Wednesday, October 28, 2009 2:44 PM  

    

Subject: Re: Zenith601-List: Flying times  

    

   

  

Hi Roger,

 

 I hope you are not including me in the "nay-sayers of the opinion that only a few people are flying" but I suspect this is indeed your interpretation.  I also object to your characterization of the problems with the Zodiac XL as "Flutter" mess.  Let me try to clear up my own position.

 

 Flutter never was a serious likelihood to explain the XL problems.  Indeed, the problems are a considerable number of fatal in-flight structural failures in the last few years.  I don't know the exact number of these events but I think it is somewhere between 5 and 10 worldwide.

 

 As to the number of grounded XLs, my belief is that nobody knows the answer to this question.  There is no official registry of flights world-wide to give a definitive answer.  We all know that several countries in Europe have grounded the XL and that one of them, the UK, has released a long list of changes that will enable owners in that country to resume flights.  As far as I know the other countries still have the XLs grounded.

 

 I appreciate the idea of having list members announce their own recent flight records.  This is a haphazard way to determine how many planes are flying vs. grounded, but it is the best one I have heard of yet.

 

 So far I have counted around 8 owners who replied that they are still flying their XLs.  For reference, the 2008 Kitplanes lists the number of completed and flying XLs as 950.  I don't know how to interpret these related numbers, but it does seem only a few are still flying.  Of course the number of responses is only a small percentage of the number actually in use.  This is a limited, but large, email list of Zodiac builders and owners, and I am sure there are a number of owners flying that have not responded.  Several list members have made it clear they are flying and have not responded to this query.

 

 If only 10 percent of the flying Zodiac XL owners have responded and the Kitplanes number is reasonably accurate that would suggest 90 percent of the fleet is grounded.  This doesn't surprise me since the NTSB asked for this result and indeed several countries (not including the USA) have responded with regulatory force on the subject.  

 

 Still, I am not sure of the real numbers, and I don't even think this really matters.  My position always has been that we don't need a consensus on this issue.  It is a decision each owner should make according to his own judgement and situation.  It is only a few very vocal folks still flying their Zodiac XLs that seem to want a justification for their choice by citing numbers of people who agree with them.  

 

 My own position since the NTSB letter has been, and remains, my plane is grounded until we get a formal release of engineering changes from Chris Heintz or one of his related companies to resolve this problem.  That change has been promised to me by Sebastian Heintz as coming "Soon".  I have no idea when his promise will be filled, but I will wait for it.  I don't know why it seems to annoy some people so much that I have chosen this path, but apparently it does.

 

 Paul

 XL awaiting engineering changes

 

 

 At 11:06 AM 10/28/2009, you wrote:

 

 

   

Approximately 90 hrs/year. 220 in total on this airframe. The real question is: how many of you have stopped flying the airplane because of this "flutter" mess. The nay-sayers are of the opinion that only a few people are flying, and they're in the majority with their decision not to fly.  I don't see anyone on ZenithAero having made that decision, and no, I don't include those don't have a finished airplane and spend their days wringing their hands and looking for another reason not to complete.    	  Quote: 	
		   	
  

    	  Quote: 	
		    href="http://www.matronics.com/Navigator?Zenith601-List">http://www.matronics.com/Navigator?Zenith601-Listhref="http://forums.matronics.com">http://forums.matronics.comhref="http://www.matronics.com/contribution">http://www.matronics.com/c 	
   	
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        [quote][b]

ter_turn(at)yahoo.com
Guest

Posted: Wed Oct 28, 2009 1:58 pm Post subject: Flying times

Ouch Doug, you've hurt my brain!  Thanks anyway.

Terry

From: Doug - SportAviation <Doug.Norman(at)sportaviation.aero>

To: zenith601-list(at)matronics.com

Sent: Wed, October 28, 2009 4:36:05 PM

Subject: RE: Zenith601-List: Flying times

Paulâ€™s right that nobody knows the actual number of â€œgroundedâ€ 601s, or those â€œstill flying.â€ And there are some weak arguments offered which claim some statistical backup for what one might conclude. Heâ€™s also correct that this isnâ€™t a consensus activity.    

If one could gather data on a reasonable sample of people who have XLs, and mine their experiences, then one could apply simple non-parametric statistics and get a handle on what the likely status is.   

Soâ€¦ I took a couple of hours and went on the Zenith.Aero site to gather what data there might be. I went and pulled the member data from the site for all the 601 XLs which are flying in the US. I then divided them into four categories:    

1)      Those who list themselves as â€œflying,â€ but thereâ€™s not enough data to put them clearly into flying or not flying (as determined by there being no activity on the site. They registered, described themselves, but no other data is there to conclude whether they are actually flying or not).   

2)      Those who are clearly flying as determined by pictures, discussions with others, etc.   

3)      Those who list themselves as flying, but are explicit about keeping themselves on the ground, or where one can reasonably infer that they are not flying   

4)      Those who register as â€œotherâ€ and who might have changed their listing from â€œflyingâ€ based on them grounding themselves.   

Remember, these are only for those people who have registered on the site. The details are below for those who want to check my math.   

The results are clear: people, as a rule, are not grounding themselves. The explanation for the continuing belief that they are grounding themselves must be due to those who are asserting this without any data to support their contention. In fact I wasnâ€™t able to find a single example of someone who had voluntarily grounded themselves on the site. But we know they exist. Paul is one. Therefore, they must represent a small slice of the owners/operators of Xls. Essentially, statistically insignificant (yet loud with assertions).   

This invalidates a number of assertions Iâ€™ve seen which suggest that the reason there are few additional episodes is probably due to the lack of flight hours. Sorry, that suggestion is not supportable.   

The most likely explanation is that people are flying within the limits of the airplane in a reasonable, responsible manner. And, isnâ€™t that what everyone should do at all times? Fly your airplanes and enjoy them.   

----------------------------------------------------------   

Here are the results:   

-          Total 601 XLs Flying in the US:     92   

-          â€œFlyingâ€ but indeterminate:         32   

-          â€œFlyingâ€ and flying:                          60   

-          â€œFlyingâ€ but grounded:                   0   

-          â€œOtherâ€ and grounded:                  0   

We now have sufficient data to test a number of hypotheses   

---------------------------------------------------   

Hypothesis 1: â€œ90% of the fleet are voluntarily groundedâ€   

To allow the best possibility of this, weâ€™ll assign all â€œFlying but indeterminateâ€ to the â€œvoluntarily groundedâ€ category.   

Now weâ€™ll perform a Chi Square in the following way:   

                Flying:    

Observed: 60     Expected: 9        (10% of 92)   

                Grounded:   

                                Observed: 32     Expected: 83     (90% of 92)   

Chi Square = 0.0001         Thus, this hypothesis is exceedingly unlikely, and we reject it.   

-------------------------------------------------------   

Hypothesis 2: â€œ50% of the fleet are voluntarily groundedâ€   

Again, to allow for the reading of the data which would most support this possibility we assign all â€œFlying but indeterminateâ€ to the â€œvoluntarily grounded categoryâ€   

                Flying:   

                                Observed: 60     Expected: 46   

                Grounded:   

                                Observed: 32     Expected: 46   

Chi Square = 0.0035         Thus, as before, we reject the hypothesis   

-----------------------------------------------------------------   

Hypothesis 3: â€œEverybody is flyingâ€   

                Flying:   

                                Observed: 60     Expected: 91   

                Grounded:   

                                Observed: 32     Expected: 1   

Chi Square = 0.0001         Thus this must be rejected too. Thus, because we canâ€™t assign the indeterminate category, we canâ€™t make this statement either.   

It turns out the largest supportable global distribution of voluntarily grounded aircraft  turns out to be about 20% IF you assume ALL indeterminates are voluntary groundings. This is probably not correct; thus, one might conclude that, among the Zenith.Aero community, there are few voluntary groundings.    

I suspect that, since there were NO explicit statements of voluntary grounding, they probably are pretty rare.   

Thus, fleet-hours are being accumulated at a rate consistent with what one would expect absent this unfortunate set of issues.    

From: owner-zenith601-list-server(at)matronics.com [mailto:owner-zenith601-list-server(at)matronics.com] On Behalf Of KARL POLIFKA

 Sent: Wednesday, October 28, 2009 3:08 PM

 To: zenith601-list(at)matronics.com

 Subject: Re: Zenith601-List: Flying times   

Rubbish.   

Karl   

  [quote]    

---

z601a(at)anemicaardvark.c
Guest

Posted: Wed Oct 28, 2009 2:51 pm Post subject: Flying times

Very erudite and thought provoking. This is about what common sense would 

suggest.



On Wednesday 28 October 2009 16:36, Doug - SportAviation wrote:

[quote] Paul's right that nobody knows the actual number of "grounded" 601s, or

 those "still flying." And there are some weak arguments offered which claim

 some statistical backup for what one might conclude. He's also correct that

 this isn't a consensus activity.



 If one could gather data on a reasonable sample of people who have XLs, and

 mine their experiences, then one could apply simple non-parametric

 statistics and get a handle on what the likely status is.



 So. I took a couple of hours and went on the Zenith.Aero site to gather

 what data there might be. I went and pulled the member data from the site

 for all the 601 XLs which are flying in the US. I then divided them into

 four categories:



 1)      Those who list themselves as "flying," but there's not enough data

 to put them clearly into flying or not flying (as determined by there being

 no activity on the site. They registered, described themselves, but no

 other data is there to conclude whether they are actually flying or not).



 2)      Those who are clearly flying as determined by pictures, discussions

 with others, etc.



 3)      Those who list themselves as flying, but are explicit about keeping

 themselves on the ground, or where one can reasonably infer that they are

 not flying



 4)      Those who register as "other" and who might have changed their

 listing from "flying" based on them grounding themselves.



 Remember, these are only for those people who have registered on the site.

 The details are below for those who want to check my math.



 The results are clear: people, as a rule, are not grounding themselves. The

 explanation for the continuing belief that they are grounding themselves

 must be due to those who are asserting this without any data to support

 their contention. In fact I wasn't able to find a single example of someone

 who had voluntarily grounded themselves on the site. But we know they

 exist. Paul is one. Therefore, they must represent a small slice of the

 owners/operators of Xls. Essentially, statistically insignificant (yet loud

 with assertions).



 This invalidates a number of assertions I've seen which suggest that the

 reason there are few additional episodes is probably due to the lack of

 flight hours. Sorry, that suggestion is not supportable.



 The most likely explanation is that people are flying within the limits of

 the airplane in a reasonable, responsible manner. And, isn't that what

 everyone should do at all times? Fly your airplanes and enjoy them.



 ----------------------------------------------------------



 Here are the results:



 -          Total 601 XLs Flying in the US:     92



 -          "Flying" but indeterminate:         32



 -          "Flying" and flying:                          60



 -          "Flying" but grounded:                  0



 -          "Other" and grounded:                  0



 We now have sufficient data to test a number of hypotheses



 ---------------------------------------------------



 Hypothesis 1: "90% of the fleet are voluntarily grounded"



 To allow the best possibility of this, we'll assign all "Flying but

 indeterminate" to the "voluntarily grounded" category.



 Now we'll perform a Chi Square in the following way:



                 Flying:



 Observed: 60     Expected: 9        (10% of 92)



                 Grounded:



                                 Observed: 32     Expected: 83     (90% of

 92)



 Chi Square = 0.0001         Thus, this hypothesis is exceedingly unlikely,

 and we reject it.



 -------------------------------------------------------



 Hypothesis 2: "50% of the fleet are voluntarily grounded"



 Again, to allow for the reading of the data which would most support this

 possibility we assign all "Flying but indeterminate" to the "voluntarily

 grounded category"



                 Flying:



                                 Observed: 60     Expected: 46



                 Grounded:



                                 Observed: 32     Expected: 46



 Chi Square = 0.0035         Thus, as before, we reject the hypothesis



 -----------------------------------------------------------------



 Hypothesis 3: "Everybody is flying"



                 Flying:



                                 Observed: 60     Expected: 91



                 Grounded:



                                 Observed: 32     Expected: 1



 Chi Square = 0.0001         Thus this must be rejected too. Thus, because

 we can't assign the indeterminate category, we can't make this statement

 either.



 It turns out the largest supportable global distribution of voluntarily

 grounded aircraft  turns out to be about 20% IF you assume ALL

 indeterminates are voluntary groundings. This is probably not correct;

 thus, one might conclude that, among the Zenith.Aero community, there are

 few voluntary groundings.



 I suspect that, since there were NO explicit statements of voluntary

 grounding, they probably are pretty rare.



 Thus, fleet-hours are being accumulated at a rate consistent with what one

 would expect absent this unfortunate set of issues.



 From: owner-zenith601-list-server(at)matronics.com

 [mailto:owner-zenith601-list-server(at)matronics.com] On Behalf Of KARL

 POLIFKA Sent: Wednesday, October 28, 2009 3:08 PM

 To: zenith601-list(at)matronics.com

 Subject: Re: Flying times



 Rubbish.



 Karl



 ---

rpf(at)wi.rr.com
Guest

Posted: Wed Oct 28, 2009 3:54 pm Post subject: Flying Times

I've been flying almost every week (spring, summer, fall  and winter) since May 2007.  Longest down time was three and a half  weeks do to weather.

  

 Randy    

 601xl

 360hrs since May 2007

 [quote]   ---

Tonyplane(at)bellsouth.ne
Guest

Posted: Wed Oct 28, 2009 4:32 pm Post subject: Flying Times

N493TG:  601XL (ser 6-5342)/Jab3300; 

 first flight Jul 05

 540 hrs; 

 1210 landings;  (231 landings on rough, short farm strip)  - now "based" on my farm

 4 annual condition inspections

 Easy to fly.  Lots of fun, inexpensive (relativity  speaking) flying.  

 (NO, I do not plan to balance my ailerons - modal surveys and  flight testings for flutter, and my own flight testing  has convinced me  there is no flutter problem within the flight envelop.  YES - I do believe  you can fail the wings with the wing removal device found on the XL and on  all airplanes, sometimes called the "stick" and on others the  "yoke".)

  

 Tony Graziano

 Buchanan, Tn

    [quote][b]

n4546v(at)mindspring.com
Guest

Posted: Wed Oct 28, 2009 7:10 pm Post subject: Flying Times

What Randy are you?  Are you my Pal Randy  Stout of San Antonio?  Are you Randy, Las vegas?  No wait that's  me.  Are you another Randy?  Need to add an identifyer  here.

  

 Regards,

  

 Randy, Las Vegas

  

  

 [quote]   ---

pfranke(at)tpg.com.au
Guest

Posted: Wed Oct 28, 2009 11:33 pm Post subject: Flying Times

Flying since March this year… 72 hours so far, and having a ball!  

   

19-7024  

Peter F in Oz  

         

  

From: owner-zenith601-list-server(at)matronics.com [mailto:owner-zenith601-list-server(at)matronics.com] On Behalf Of BobbyPaulk(at)comcast.net

 Sent: Thursday, 29 October 2009 12:50 AM

 To: zenith601-list-digest(at)matronics.com

 Subject: Flying Times  

  

     

Guys 

 can we get a show of hands on who is flying and how much. i would have done much more except for weather and runway construction. went to a fly-in 100 miles away. good time, good food. indicated 125 mph at 5500' with a 155 mph ground speed

 hopefully we are getting better weather. 

 

 N131BP

 601 XL E-AB

 14hrs since June  

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yak52

Joined: 25 Oct 2007
Posts: 50

Posted: Thu Oct 29, 2009 7:35 am Post subject: Flying times

Hi Paul:

  

 Actually, I recently conducted a poll on the ZBAG list. The results were for a period of 3 months this summer. There were  32 different people responding to anything posted on the list.  Of those  who responded to the poll: anonymously, I might add so they would feel free to speak their real feelings:

   

 44% didn't believe the FAA statement that the 601xl is capable of safe flight if built and flown according to manufacturers specifications(11 of 25)

  

 37.5% didn't believe The Austrian GVT testing and the opinions expressed as a result of that testing(one of them, who has wholeheartedly embraced the LAA tried and true method of conducting GVT testing of putting  wood on the wingtip and whacking it with a hammer, actually wanted "independent" verification of the Austrian GVT testing).(6 0f 16)

   

  

 So when you write:

  

 "I hope you are not including me in the "nay-sayers of the opinion

that only a few people are flying" but I suspect this is indeed your

interpretation"

  

 We need only look at your subsequent statements:

  

 "If only 10 percent of the flying Zodiac XL owners have responded and

the Kitplanes number is reasonably accurate that would suggest 90

percent of the fleet is grounded."

  

 and 

  

 " but it does seem only a few are still

flying. "

  

 Accordingly, I think you placed yourself in that group.

  

 Secondly, your statements:

  

 "  I also object to your characterization of the

problems with the Zodiac XL as "Flutter" mess.  Let me try to clear

up my own position.

 Flutter never was a serious likelihood to explain the XL

problems. "

  

  

 are belied by your actions. I was present at Sun-n-Fun.  A  whole tentful of people saw and heard  you shout  repeatedly at the Heintz brothers that the NTSB says flutter is the problem and when are you going to fix the ailerons so many times that the rest of the crowd told you to shut up and let other people speak.  You then proceeded to stalk the brothers across the area back to the Zenith display where you continued the harange until you left the area. If flutter was never a serious likelihood, why such actions? 

   

  

 Third, the statement:

  

 "  It is only a few very vocal folks still flying their Zodiac XLs that seem to want a

justification for their choice by citing numbers of people who agree

with them." 

  

 appears to be contraindicated. Actually the statistics support the proposition that it is a very vocal minority that are engaged that are justifying their position by refusing to believe any test, study or opinion that is at variance with the NTSB statement. 

   

  

 Fourth:

  

 "My own position since the NTSB letter has been, and remains, my plane

is grounded until we get a formal release of engineering changes from

Chris Heintz or one of his related companies to resolve this

 problem."

  

 Which problem is that? If its not flutter( as per the NTSB, which you now say never a serious likelihood),what is(are) it(they)?   Give us all an engineering analysis by an aeronautical engineer willing to actually sign his name to a document for public review that actually states the casual factor( the assumption implicit by the hand wringers in all this of their being only one) of the crashes and how to fix it. The FAA, NTSB, LAA and ZBAG despite millions of dollars haven't been able to do it .

   

 Lastly:

  

 "  I don't know why it seems to annoy some people so

much that I have chosen this path, but apparently it does."

  

 Perhaps its the circular logic, you continually state:

  

 1. I won't fly because of the NTSB letter saying flutter is the cause of the accidents.

 2. Flutter was never a serious likelihood to explain the accidents.

 3. I still won't fly because of the NTSB flutter letter. 

  

 Personally, I hope CH does come up with something, anything, to stop this ceaseless game of Whack-a-Mole being played by some members of these groups. If its not flutter, its rivit strength, or aileron bellcrank support or the rear spar attach or the hole in the rear spar for the aileron actuator rod. All most of us ever wanted was reputable analysis of the accidents for causation and some engineered fix. It would have been easy for CH to just put forth an external mass balanced aileron for everyone and pretend the problem is solved. Fortunately or unfortunately, he has too much integrity and has done, and paid for,  those  tests and studies to determine potential causes and solutions. Let's see what he comes up with. It all the accidents had one single cause, it would have been apparent and identified by now. It it were one design flaw, it would be happening to every aircraft built in accordance with that design operated within the same flight envelope. Risk managment is the goal, risk elimination is a figment of imagination.

  [quote][b]

psm(at)att.net
Guest

Posted: Thu Oct 29, 2009 8:21 am Post subject: Flying times

Hi Roger,



I really appreciate your comments.  Instead of making personal 

attacks, as some have done, you are making reasonably logical 

comments on my actual statements.  I will try my best to give you 

straight answers to your questions.



I never thought flutter was an issue with the XL.  My reason is the 

fact observed by witnesses to a couple of the accidents that the 

breakups tend to happen in level flight at moderate to slow 

speeds.  My understanding of flutter is that it is a high speed 

phenomenon and that increased speed greatly increases the likelihood.



In my personal interpretation of the NTSB letter, the real issue was 

always the structure failures and the comments about flutter were 

just a side issue.  The NTSB is in the business of analyzing 

accidents and their causes rather than engineering and design 

choices.  We all know the airplanes failed and lots of people 

died.  What ever the underlying cause of the failures is this simple 

fact is the basis of the NTSB letter and my own feelings.  OK, this 

may not be the only way to read the letter, but it is indeed my interpretation.



I understand some people were so focused on the question of flutter 

it didn't matter what I or anyone else said.  They simply heard 

"Flutter problem" rather than what was actually said.



I don't feel qualified to have a professional opinion on the 

underlying cause of the failures.  With that caveat, I do have a 

personal opinion about the basic problem.  I think the light pitch 

control forces and the gradient problem first identified in the NTSB 

letter are the root of the problem.  I also know there is some 

"Problem" that causes loud vibrations in level flight as reported by 

Bill of GA.  His winning solution for this problem was not a speed 

reduction - the normal solution if flutter is a problem - but 

unloading the wings by entering a steep bank.  I don't think the 

noisy vibration is actually fatal, but I think some pilots respond to 

this phenomenon as if it were flutter and sharply pull and push the 

stick removing the wings.  If this is indeed true and not just my own 

personal musing then the change already announced by Chris Heintz to 

reduce the pitch sensitivity with some sort of springs will indeed 

help reduce the accident rate.  It also means those pilots who are 

cool enough in an "Emergency" situation to maintain gentle control 

forces will be safe in XLs with or without the engineering change.



On to another engineering point . . . even though I am convinced 

flutter is not a problem I am still willing to install a mass balance 

change on the ailerons of my plane.  My reasoning may be impossible 

to follow, but here it is.  I have heard many "Old timers" from the 

FAA and my local pilot community say that this is a necessary change 

for safety.  They can't convince me that the XL has a flutter problem 

and this fixes it.  They have convinced me that planes with balanced 

control surfaces (virtually all existing planes with metal control 

surfaces) have better safety records.  Put this all together and you 

can see I am willing to add a few pounds to my plane to get the 

ailerons balanced simply because I think it might help and can't hurt.



I hope I have answered your questions.  The only point I want to 

emphasize is that the changes I want have already been promised from 

Chris with no specific delivery date other than "Soon".  My decision 

to wait for those changes and install them in my plane shouldn't 

upset anyone.  Since my "Choice of words" seems to upset some people 

I am indeed sorry.  I am trying to be straight forward with my ideas 

without inflammatory language.



I do want to make one more comment.  I have started building a 

Wittman Buttercup and have joined several email lists relating to 

that airplane and its builders/owners.  I have not seen a single 

instance of the kind of abrasive personal attacks that regularly 

happen on this list.  Perhaps it is because the other group is mostly 

experienced builders rather than first timers like the Zenith 

community.  I wish there were some magic wand I could wave to get the 

Zenith community to act more professionally and with less personal attacks.



If I left out any significant points please let me know.  I meant to 

answer all your concerns, but I am not perfect - particularly in the 

memory area.



Paul

XL awaiting engineering changes





At 08:31 AM 10/29/2009, you wrote:

 	  Quote: 	
		    If flutter was never a serious likelihood, why such actions?

fgantt(at)texaviation.com
Guest

Posted: Thu Oct 29, 2009 8:57 am Post subject: Flying times

PaulI think we grow tired of the constant posting of known facts.Why can't we wait and see what Chris and Zenith Aircraft's final report recommends. Each person has made their own decision to ground or not to ground their airplane. I think the statement ,"I do want to make one more comment. I have started building a Wittman Buttercup and have joined several email lists relating to that airplane and its builders/owners. I have not seen a single instance of the kind of abrasive personal attacks that regularly happen on this list. Perhaps it is because the other group is mostly experienced builders rather than first timers like the Zenith community. I wish there were some magic wand I could wave to get the Zenith community to act more professionally and with less personal attacks",is condescending  and unnecessary.



Floyd Gantt

From: "Paul Mulwitz" <psm(at)att.net>Sent: Thursday, October 29, 2009 11:26 AMTo: zenith601-list(at)matronics.comSubject: Re: Flying times--> Zenith601-List message posted by: Paul Mulwitz

Hi Roger,I really appreciate your comments.  Instead of making personal attacks, as some have done, you are making reasonably logical comments on my actual statements.  I will try my best to give you straight answers to your questions.I never thought flutter was an issue with the XL.  My reason is the fact observed by witnesses to a couple of the accidents that the breakups tend to happen in level flight at moderate to slow speeds.  My understanding of flutter is that it is a high speed phenomenon and that increased speed greatly increases the likelihood.In my personal interpretation of the NTSB letter, the real issue was always the structure failures and the comments about flutter were just a side issue.  The NTSB is in the business of analyzing accidents and their causes rather than engineering and design choices.  We all know the airplanes failed and lots of people died.  What ever the underlying cause of the failures is this simple fact is the basis of the NTSB letter and my own feelings.  OK, this may not be the only way to read the letter, but it is indeed my interpretation.I understand some people were so focused on the question of flutter it didn't matter what I or anyone else said.  They simply heard "Flutter problem" rather than what was actually said.I don't feel qualified to have a professional opinion on the underlying cause of the failures.  With that caveat, I do have a personal opinion about the basic problem.  I think the light pitch control forces and the gradient problem first identified in the NTSB letter are the root of the problem.  I also know there is some "Problem" that causes loud vibrations in level flight as reported by Bill of GA.  His winning solution for this problem was not a speed reduction - the normal solution if flutter is a problem - but unloading the wings by entering a steep bank.  I don't think the noisy vibration is actually fatal, but I think some pilots respond to this phenomenon as if it were flutter and sharply pull and push the stick removing the wings.  If this is indeed true and not just my own personal musing then the change already announced by Chris Heintz to reduce the pitch sensitivity with some sort of springs will indeed help reduce the accident rate.  It also means those pilots who are cool enough in an "Emergency" situation to maintain gentle control forces will be safe in XLs with or without the engineering change.On to another engineering point . . . even though I am convinced flutter is not a problem I am still willing to install a mass balance change on the ailerons of my plane.  My reasoning may be impossible to follow, but here it is.  I have heard many "Old timers" from the FAA and my local pilot community say that this is a necessary change for safety.  They can't convince me that the XL has a flutter problem and this fixes it.  They have convinced me that planes with balanced control surfaces (virtually all existing planes with metal control surfaces) have better safety records.  Put this all together and you can see I am willing to add a few pounds to my plane to get the ailerons balanced simply because I think it might help and can't hurt.I hope I have answered your questions.  The only point I want to emphasize is that the changes I want have already been promised from Chris with no specific delivery date other than "Soon".  My decision to wait for those changes and install them in my plane shouldn't upset anyone.  Since my "Choice of words" seems to upset some people I am indeed sorry.  I am trying to be straight forward with my ideas without inflammatory language.I do want to make one more comment.  I have started building a Wittman Buttercup and have joined several email lists relating to that airplane and its builders/owners.  I have not seen a single instance of the kind of abrasive personal attacks that regularly happen on this list.  Perhaps it is because the other group is mostly experienced builders rather than first timers like the Zenith community.  I wish there were some magic wand I could wave to get the Zenith community to act more professionally and with less personal attacks.If I left out any significant points please let me know.  I meant to answer all your concerns, but I am not perfect - particularly in the memory area.PaulXL awaiting engineering changesAt 08:31 AM 10/29/2009, you wrote:>  If flutter was never a serious likelihood, why such actions?

    [quote][b]

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