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bryanmmartin

Joined: 10 Jan 2006
Posts: 1018

Posted: Wed Mar 12, 2008 12:36 pm Post subject: Accident

The 601XL is rated for a maximum of +/-4G flight load limit, the +/-6G 

is the design load limit. Flight load limit is the maximum load the 

airplane should ever experience in flight, exceeding the design load 

limit may result in structural failure.



This is a common point of confusion because most factory built aircraft 

use the flight load limit in the flight manuals but most amateur built 

aircraft kit makers use the design load limit in their sales literature. 

If someone does get confused on this point and flys the plane to the 

design load limit, there is a real risk of structural failure.



mwtucker wrote:

 	  Quote: 	
		   

 

 

 What type of flight testing has the 601XL design been through?  Are there any flight test requirements that subject the airframe to the limits of the loading?  I think the plane is rated to +/- 6 G?  Does flight testing require that to be demonstrated?

 


	


-- 

Bryan Martin

Zenith 601XL N61BM

Ram Subaru, Stratus redrive

Do Not Archive

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

eldenej(at)yahoo.com
Guest

Posted: Wed Mar 12, 2008 1:13 pm Post subject: Accident

What, pray tell, is the point of your anti-government rant?

   

  Elden J.

  xl/3300



Paul Mulwitz <psm(at)ATT.NET> wrote:

  [quote]--> Zenith-List message posted by: Paul Mulwitz 



To my recollection, NASA has a long history of screwing up nearly 

everything they ever did. I attribute this to the fact they are a 

government bureaucracy, they buy most of their stuff from the lowest 

bidder, and they have no profit motive to move them toward perfection 

or even a satisfactory outcome. They are much more motivated by 

political and publicity pressures than anything else. I would never 

give even remote consideration to an offer to ride in a NASA space 

craft. (These are also the guys who spend millions of our dollars 

each year trying to develop a personal airplane that  can fly itself 

so the masses can enjoy personal flight without learning how to be a pilot.)



I agree that discussion of the facts and even some conjecture about 

the XL design is healthy. Where I get concerned is when someone with 

about zero qualifications as an aircraft designer offers one 

ridiculous design change after another to fix problems that have not 

even been indicated let alone established as fact. I realize most 

readers of the list can tell when someone is making ridiculous 

suggestions, but I am afraid there are some who might implement some 

of those design changes and suffer the outcome.



I am convinced that Chris Heintz has done a wonderful job designing 

this airplane. I am also convinced that any design changes 

considered by a kit or plans builder should be approved by one of the 

engineering support people readily available to us to consider such 

changes. While this is not a perfect system, it is the [quote][b]

swater6

Joined: 16 Dec 2006
Posts: 52
Location: Minnesota-KMIC/KANE

Posted: Wed Mar 12, 2008 1:31 pm Post subject: Re: Accident

FYI if you're not looking at the "British 601 Crash" , go there and look towards the bottom at a message from Rick Lindstrom.  He has some insight......

_________________
601 XL kit N596SW reserved
Tail, control surfaces and both wings complete. Now working on fuselage

www.scottwaters.com

psm(at)att.net
Guest

Posted: Wed Mar 12, 2008 2:56 pm Post subject: Accident

Hi Eldon,



I was responding to the notion, posted by another list member,  that 

all the millions of dollars spent by NASA on engineering means they 

do good work.  That is a preposterous notion considering the results 

they have had.



Perhaps you remember the Hubble Space Telescope?  That was completely 

wasted for years until NASA dispatched a shuttle mission to replace 

the final stage of the optics chain.  It seems they didn't bother to 

consider the lenses would be operating in a vacuum rather than in air.



And then there was the recent solar wind collector mission that was 

ruined because they installed a three pin electronic component 

backwards in the circuit used to open the parachute on reentry.



  NASA history is full of such stupid mistakes.



I will accept responsibility for an anti-NASA rant.  As to the 

government in general, I remain somewhat more neutral.  I am not an 

anarchist, but I do believe bureaucracies are inherently poor at 

doing anything - especially anything that requires creativity.   I 

also understand they are necessary for some functions.



Paul

XL fuselage

do not archive

At 02:09 PM 3/12/2008, you wrote:



 	  Quote: 	
		  What, pray tell, is the point of your anti-government rant?



Elden J.

xl/3300

craig(at)craigandjean.com
Guest

Posted: Wed Mar 12, 2008 3:13 pm Post subject: Accident

 	  Quote: 	
		   It seems they didn't bother to consider the lenses would be operating in a vacuum rather than in air.


	


Not true:



http://en.wikipedia.org/wiki/Hubble_Space_Telescope



"Working backwards from images of point sources, astronomers determined that the conic constant of the mirror was −1.01324, instead of the intended −1.00230. The same number was also derived by analyzing the null correctors (instruments which accurately measure the curvature of a polished surface) used by Perkin-Elmer to figure the mirror, as well as by analyzing interferograms obtained during ground testing of the mirror.



A commission headed by Lew Allen, director of the Jet Propulsion Laboratory, was established to determine how the error could have arisen. The Allen Commission found that the null corrector used by Perkin-Elmer had been incorrectly assembled. Its field lens had then been wrongly spaced by 1.3 mm.[16]



During the polishing of the mirror, Perkin-Elmer had analyzed its surface with two other null correctors, both of which (correctly) indicated that the mirror was suffering from spherical aberration. These tests were specifically designed to eliminate the possibility of major optical aberrations. Against written quality guidelines, the company ignored these test results as it believed that the two null correctors were less accurate than the primary device which was reporting that the mirror was perfectly figured.



The commission blamed the failings primarily on Perkin-Elmer. Relations between NASA and the optics company had been severely strained during the telescope construction due to frequent schedule slippage and cost overruns. NASA found that Perkin-Elmer had not regarded the telescope mirror as a crucial part of their business and were also secure in the knowledge that NASA could not take its business elsewhere once the polishing had begun. While the commission heavily criticized Perkin-Elmer for these managerial failings, NASA was also criticized for not picking up on the quality control shortcomings such as relying totally on test results from a single instrument.[17]"



-- Craig

MHerder

Joined: 11 Feb 2008
Posts: 143
Location: Fort Worth TX

Posted: Wed Mar 12, 2008 3:38 pm Post subject: Re: Accident

I think that you can get the point about what  I was trying to say.  If you don't like NASA, then substitute the name of a successful  agency/company followed by an accident that they made.  I don't think it is a " a preposterous notion" that NASA has a team of intelligent folks who do for the most part good work.   (some who may or may not find themselves in a love triangle wearing diapers while driving to Florida to kill their husbands mistress).  Burt Rutan has also done an incredible in his quest for space.  Burt Rutan and his space team AND NASA both do good work.   And both have made mistakes.  Please tell me who has done a better job with space exploration besides NASA?  



 	  psm(at)att.net wrote: 	
		  Hi Eldon,



I was responding to the notion, posted by another list member,  that 

all the millions of dollars spent by NASA on engineering means they 

do good work.  That is a preposterous notion considering the results 

they have had.



Perhaps you remember the Hubble Space Telescope?  That was completely 

wasted for years until NASA dispatched a shuttle mission to replace 

the final stage of the optics chain.  It seems they didn't bother to 

consider the lenses would be operating in a vacuum rather than in air.



And then there was the recent solar wind collector mission that was 

ruined because they installed a three pin electronic component 

backwards in the circuit used to open the parachute on reentry.



  NASA history is full of such stupid mistakes.



I will accept responsibility for an anti-NASA rant.  As to the 

government in general, I remain somewhat more neutral.  I am not an 

anarchist, but I do believe bureaucracies are inherently poor at 

doing anything - especially anything that requires creativity.   I 

also understand they are necessary for some functions.



Paul

XL fuselage

do not archive

At 02:09 PM 3/12/2008, you wrote:



 	  Quote: 	
		  What, pray tell, is the point of your anti-government rant?



Elden J.

xl/3300

_________________
Zodiac 601 HD
Jabiru 3300
Wood Sensinich 64x47
Finally Flying

rsteele(at)rjsit.com
Guest

Posted: Wed Mar 12, 2008 3:40 pm Post subject: Accident

NASA didn't build the flawed mirror in Hubbble, Perkin Elmer did. They

didn't design or build the solid rocket booster of Shuttle shame.  One

does have to wonder what the contracts for testing looked like on that

mirror.



NASA has designed AND built an incredible number of very successful

spacecraft, pushing the limits of known engineering on nearly every one.

 Some failures for sure, but overall an outstanding success rate in my

opinion.



Ron

------

purplemoon99(at)bellsouth
Guest

Posted: Wed Mar 12, 2008 4:25 pm Post subject: Accident

Would Dread be willing manage the money for us  ? we all know him, and he 

would be a good netural party....Joe N101HD 601XL/RAM

---

psm(at)att.net
Guest

Posted: Wed Mar 12, 2008 5:03 pm Post subject: Accident

Actually, I could do that, but it would be illegal for me to give you 

any details since they are still highly classified.  The short answer 

is the US military space program.  For a longer and already 

declassified answer take a look at WWW.NRO.MIL.  Pay particular 

attention to the project called "Corona".



The only thing I will say is that I have personal knowledge of some 

of the things done there, and I don't believe there were any 

significant stupid mistakes like the kind common at NASA.  It was, 

however, still a government operation but without much of the 

bureaucracy that cripples most of the government.



Paul

XL fuselage

do not archive



At 04:38 PM 3/12/2008, you wrote:



 	  Quote: 	
		  I think that you can get the point about what  I was trying to 

say.  If you don't like NASA, then substitute the name of a 

successful  agency/company followed by an accident that they 

made.  I don't think it is a " a preposterous notion" that NASA has 

a team of intelligent folks who do for the most part good 

work.   (some who may or may not find themselves in a love triangle 

wearing diapers while driving to Florida to kill their husbands 

mistress).  Burt Rutan has also done an incredible in his quest for 

space.  Burt Rutan and his space team AND NASA both do good 

work.   And both have made mistakes.  Please tell me who has done a 

better job with space exploration besides NASA?

davidl409(at)comcast.net
Guest

Posted: Wed Mar 12, 2008 7:05 pm Post subject: Accident

I to would be willing to contribute to an independent study if enough people

were involved. I have a 601xl project about 90 % complete,  with wing

lockers and dual 12 gallon tanks which were the options available in May

2004. I don't remember any wing failures at that time or I might not have

selected the 601xl. 



--

tonyplane(at)bellsouth.ne
Guest

Posted: Wed Mar 12, 2008 8:59 pm Post subject: Accident

Just my two cents.

  

 I too am curious about the Australian aircraft  accident investigation board findings, but I have confidence in the  structural integrity of my XL that I built from a kit and flew on its  maiden flight --------------- as long as I fly it in its RECOMMENDED FLIGHT ENVELOPE.

  

 I now have 357  hours and over 700  take-offs/landings on my 601XL/Jab3300. It has wing lockers and aux  tanks. I flew it once in a gradual build up of runs in calm air to +8%  over Vne or 195 MPH IAS in Phase I, in a shallow dive at max recommended  RPM.  (some have speculated the XL could NEVER reach  200 mph -------- YES it can easily!! .... and even go faster ... before it  possibly breaks up)

  

 I have flow in gusty teeth chattering conditions  (make sure you have a tight seat belt and slow down to Va.) with no  problems.  The XL can be flown in these conditions, but does require more  attention like any other airplane.

  

 Once in Phase I testing, I was holding it in a  stall buffet trying to get it to break (was in a buffeting stall condition for  an extended period of time) when it abruptly pitched nose straight down  (negative Gs) from I suspect a gust that stalled the Horiz stab.  If  my seat belt had not been secured, I am sure I would have been thrown through  the canopy.  I have done probably close to a hundred or more stalls  during airwork exercises at most flight conditions/flap settings/power  settings and find the XL to be benign in the stall.  I find the  airplane to be easy to fly also.

  

 I believe I can  induce catastrophic  structural damage to my XL (and most other airplanes) if I were  to apply sudden full stick deflections at high speed or going to Vne  in a dive and applying abrupt near max control deflections for a rolling,  turning pullout. - NO, I am not going to try it.  

  

 There are a lot of hawks, eagles, buzzards  in my part of Tennessee.  I look very carefully below 2000 ft for  birds, as I suspect a canopy strike would be a BAD problem in the  XL, ........ or in C-150/172/182/Piper etc.

  

  

 Tony Graziano

 Buchanan, Tn

 N493TG

  

   [quote][b]

japhillipsga(at)aol.com
Guest

Posted: Thu Mar 13, 2008 8:48 am Post subject: Accident

Tony, your words of wisdom and experience should encourage some of the more chicken hearted folks, but for those truly afraid buy a parachute and a helmet, a fire extinguisher, a canopy axe, two ELTs and a survival vest and fly something else. Tony are you planning on going to SnF this April? Would enjoy meeting you and best regards, 

   Bill of Georgia

   N505WP

   601XL-3300 126 hours 

 

 --

reinkings(at)comcast.net
Guest

Posted: Thu Mar 13, 2008 11:44 am Post subject: Accident

I'm in.



John Reinking

Woodinville, WA

psm(at)ATT.NET
Guest

Posted: Thu Mar 13, 2008 11:52 am Post subject: Accident

Hi Sabrina,



Thanks for all the interesting comments.  Let me 

add a few questions and answers of my own.



The XL doesn't have a header tank.  All the fuel is stored in the wing tanks.



I don't understand your comment about Normal 

category flight.  The XL is not designed for aerobatic flight.



I would like more information on your ejector 

canopy.  I think a personal parachute would be a 

wise thing to have - especially for initial 

flight testing.  However, I don't know of any 

technique for bailing out of a plane with a front 

hinged canopy.  Detailed design information would 

be greatly appreciated.  I actually asked 

Sebastian Heintz about this before starting 

building my XL.  He made a joke about it and said 

the "Egress system has not been tested" or some such cute remark.



I think the aileron twist is done to give the 

wing some washout.  This makes the stall take 

place at the root before the tips and allows for 

better control during a stall.  I don't think the 

twist has much of any other impact.



I don't understand you comment about centering 

the flaps on the rear spar.  The flaps are 

mounted on the bottom flange of the spar.  How could they be centered?



I just got a phone quote from Falcon insurance 

for EAA coverage of my XL.  They said the price 

for liability would be around $600 per 

year.  Hull insurance varied from around $700 for 

non-flying coverage to around $2100 for full hull 

coverage.  The hull quotes were based on a 

$50,0000 value for the plane.  The broker I spoke 

to seemed to think the Zodiac was a fine 

experimental plane, and also said the companies 

he uses for EAA coverage don't distinguish 

between a private pilot flying with full 

privileges or one limited to Sport Pilot 

privileges -  the premiums are the same.  As to 

pilot experience, he said a couple of hours (yes 

2) in type would be helpful.  Oddly, he said in 

my case (Sport Pilot limited private pilot) my 

wife could be covered as a student pilot only if 

she was training for a Private Pilot license 

rather than a Sport Pilot license.  This 

restriction applied to only one of the two 

insurance companies he uses (I think it was AIG)



I suspect the issue of time in type and checkout 

requirements vary considerably from one insurance 

company to another.  I have found the EAA 

arranged coverage seems to fit recreational 

flying well while insurance packages arranged for 

more conventional airplane owners have a 

completely different set of requirements.  Lets 

face it - people have a very hard time finding 

experimental airplanes to get dual instruction 

in, but those who buy Cessnas can get dual time at nearly any local airport.



Paul

XL fuselage

At 08:12 AM 3/12/2008, you wrote:

 	  Quote: 	
		  I too bought the kit before the first major 

failure.  I held off building the wings until last.



Common sense would tell you to fly this aircraft 

in the Normal category until more facts are in.



Explosions of header fuel tanks, be they 8 

gallons or 1 gallon can lead directly to spar 

failure and wing fold in any design.



An ejector canopy with a pilot parachute are an 

inexpensive option, just make sure you have room to duck.



Engine vibration due to plug fouling can lead to 

an increased load on the airframe.  Compare the 

XL O-200A engine mount with the Cessna 150 mount.



Looking at XLs over the years, one notices the following:



Failure to twist the ailerons 2.5 degrees. (6-W-2)



Evidence of excessive flexing due to wind damage 

at the top of the aileron, inboard attach point.



Failure to include an upper elevator stop (the 

shoe is often beyond 32 degrees). (6-S-4)



Failure to center the flaps on the rear spar, 

they often rise too far above or are set too far below the spar. (6-W-00)



Drilling too large of an aileron control rod 

hole, or placing it too low in the rear spar near rib 7. (6-W-00)



Not having dL = dR (6-S-3).   In light of recent 

events there is no excuse for being anywhere 

near the +/- 50 mm tolerance allowed by the designer.



Failure to properly attach the rear spars 

including failure to set the top aft edge of 

both to an equal distance below the longeron 

reference line; improper use of shims between 

the 6B5-4 attach plate and the rear spar; the 

rear spar mounted on the wrong side of the attach plate. (6-S-3)



Fly the factory Zenith, see how much elevator 

input they will allow you to use in cruise 

flight before they turn white and take over the controls.



Remember, with the flaps in any position but up, 

even a Cessna 150 Aerobat  is NOT certified to 

intentionally experience ANY negative Gs.



What are people paying for XL insurance, $30,000 

hull coverage and $1M liability?



My 150 comes in just over $600, whereas the 

quotes for the XL winged aircraft now exceed 

$2,000, they won’t insure Phase 1 for hull 

damage, they won’t insure a solo student 

pilot, or anyone without 10 hours of dual in the aircraft or 40 hours in type.

psm(at)ATT.NET
Guest

Posted: Thu Mar 13, 2008 1:19 pm Post subject: Accident

Hi Mike,



You ask some very important questions.  I wish I 

had the answers, but I don't.  What I do have is 

three years of working daily on my XL and all the 

other experiences that went along with that.



I have often considered what other plane I would 

like to build.  I still haven't found a design 

that meets my needs and desires better than the 

XL.  It offers the basic things I want and gives 

the maximum amount allowed for each area.  I want 

an LSA legal plane with two seats that are side 

by side.  I also want nose gear steering, flaps, 

and appropriate controls and trim and reasonable 

handling and performance.  While I would like a 

plane good for long cross country trips, day 

trips are more likely for me to take since I 

don't really like to travel.  I also wanted an 

all metal design since that seems the best suited 

to the rain forest climate I live in.  (Funny 

thing, Van's company is located here and makes all metal kit planes.)



The RV-12 doesn't work for several reasons.  I 

don't like the fact it is limited to the Rotax 

engine.  It doesn't have nose gear 

steering.  Also, it is not yet available on the market.



I am concerned about the structural failures 

experienced on XLs.  I am also not convinced 

there is an unusually high number of such 

failures.  I know there are many XLs flying with 

no problems.  I feel there is always some danger 

in flying experimental AB airplanes and the 

Zodiac may or may not be among the safest 

examples of that type of plane.  There is also 

some danger flying factory built planes, but you 

get to pay a lot more for that type.



I intend to fly my XL using all the skill I 

currently have and any additional skill I can 

develop.  I firmly believe safe flight is mostly 

a matter of pilot skill and performance.  There 

are many years of data that say pilot error is 

the most likely cause of any aviation 

accident.  I believe this applies to 

experimental-AB planes as well as certified types.



If there is an additional few percent chance that 

the XL will fail on me then I am willing to 

accept that risk.  The joy of flying a plane I 

built with my own hands and brain makes up for 

that.  If I wind up getting killed as a result of 

a freak structural failure, then . . . well . . . 

I can't think of a better way to go.  I have 

already lived longer than most humans throughout 

history, and I am sure I will die from some cause or another eventually.



Good luck with your decision.



Paul

XL fuselage

At 10:56 PM 3/11/2008, you wrote:

 	  Quote: 	
		  



It is easy to try and second-guess a design 

based on some supposed “facts” from media 

stories and “eyewitnesses”.  Yes, it’s 

true that most of us are not aeronautical 

engineers…  But I think that it is 

constructive to discuss the accidents, keeping 

in mind that we may not know all the 

facts.  That said, it does seem that we may want 

to make note of the fact that wing structural 

failure seems to be coming up as a common 

thread.  Has wing structural failure been 

mentioned in relation to accidents of other 

aircraft (even certified designs)?  We all know 

that flight into thunderstorms and/or loss of 

control can over-stress the airframe and result in failure….



But I must admit that I am a bit concerned about 

the “supposed” in-flight structural failures 

on the 601XL.  I know that Chris Heintz did a 

re-evaluation of the wing structure and loading 

after two supposed in-flight wing failure 

accident reports.  But these were static load 

tests and would not expose any dynamic problems 

related to flutter or torsional deflections that may lead to wing failure.



I have attended the rudder workshop at Zenith 

and am getting pretty close to making the 

commitment to go with a 601XL.  I plan to ask 

them at Sun-n-Fun about the wing “issue”, 

although I would imagine that they will not tell 

me anything that I don’t already know.  Again, 

we don’t want to jump to conclusions.  I could 

wait and go with a Vans S-12 or a RANS 

19…  But those are new designs and could also 

have “design” problems.  In fact, one of the 

reasons I was looking at the 601 XL is that the 

designer is well-known and respected and the 

design has been flying for awhile….



Does anyone know if there are any similar 

“structural failures” on other AB 

aircraft?  Again, we are assuming that there 

was, in fact a structural wing failure.  I guess 

that we don’t really know for sure.



What type of flight testing has the 601XL design 

been through?  Are there any flight test 

requirements that subject the airframe to the 

limits of the loading?  I think the plane is 

rated to +/- 6 G?  Does flight testing require that to be demonstrated?



As to Jay’s comment “why are we building the 

601XLs in light of the alleged in-flight 

structural failures?”  I imagine that most 

people who are in the process of building a 

601XL started their kits before they were aware 

of the several accidents in question.



Some responses on the forum are suggesting that 

the aircraft will be fine as long as it is flown 

properly…  In a 172, I once ran into clear-air 

turbulence over the mountains of Pennsylvania 

and it scared me to death.  There was nothing I 

could do to prevent that incident.  Can the 601XL survive an upset like that?



Let me close in saying that we don’t really 

know for sure about the “potential” 

structural failures.  It’s possible that they 

could all be explained by airframe failure due 

to loss of control by the pilot (e.g. 

birdstrike, flight into storm, accidental rapid 

movement of the controls, etc.).



Thanks, Mike

Gig Giacona

Joined: 10 Jan 2006
Posts: 1416
Location: El Dorado Arkansas USA

Posted: Thu Mar 13, 2008 2:02 pm Post subject: Re: Accident

Well said Paul.



DO NOT ARCHIVE

_________________
W.R. "Gig" Giacona
601XL Under Construction
See my progress at www.peoamerica.net/N601WR

planecrazydld(at)yahoo.co
Guest

Posted: Thu Mar 13, 2008 2:27 pm Post subject: Accident

Hi Paul;



I believe the reference to centering the flaps is related to the thickness of the flap being considerably over the thickness of the contour of the wing airfoil immediately ahead of the retracted flap (about 0.240"). The referenced drawing calls for the 3 mm above local contour and 3mm below local contour - centered.



As for the aerobatic flight reference, why do you think Zenith keeps the looping XL video on its company web page? Many pilots do not have an understanding of the rate of acceleration that occurs when a maneuver is botched - I almost pulled the wings off a 150 back in 1976 when I screwed up a solo departure stall. All I remember was the engine screaming and the ASI pegged with the VSI going around like a clock spring unwinding...I had a new instructor the next flight!



Paul Mulwitz <psm(at)att.net> wrote:[quote]  --> Zenith-List message posted by: Paul Mulwitz 



Hi Sabrina,



Thanks for all the interesting comments.  Let me 

add a few questions and answers of my own.



The XL doesn't have a header tank.  All the fuel is stored in the wing tanks.



I don't understand your comment about Normal 

category flight.  The XL is not designed for aerobatic flight.



I would like more information on your ejector 

canopy.  I think a personal parachute would be a 

wise thing to have - especially for initial 

flight testing.  However, I don't know of any 

technique for bailing out of a plane with a front 

hinged canopy.  Detailed design information would 

be greatly appreciated.  I actually asked 

Sebastian Heintz about this before starting 

building my XL.  He made a joke about it and said 

the "Egress system has not been tested" or some such cute remark.



I think the aileron twist is done to give the 

wing some  washout.  This makes the stall take 

place at the root before the tips and allows for 

better control during a stall.  I don't think the 

twist has much of any other impact.



I don't understand you comment about centering 

the flaps on the rear spar.  The flaps are 

mounted on the bottom flange of the spar.  How could they be centered?



I just got a phone quote from Falcon insurance 

for EAA coverage of my XL.  They said the price 

for liability would be around $600 per 

year.  Hull insurance varied from around $700 for 

non-flying coverage to around $2100 for full hull 

coverage.  The hull quotes were based on a 

$50,0000 value for the plane.  The broker I spoke 

to seemed to think the Zodiac was a fine 

experimental plane, and also said the companies 

he uses for EAA coverage don't distinguish 

between a private pilot flying with full 

privileges or one limited to Sport Pilot 

privileges -  the premiums are  the same.  As to 

pilot experience, he said a couple of hours (yes 

2) in type would be helpful.  Oddly, he said in 

my case (Sport Pilot limited private pilot) my 

wife could be covered as a student pilot only if 

she was training for a Private Pilot license 

rather than a Sport Pilot license.  This 

restriction applied to only one of the two 

insurance companies he uses (I think it was AIG)



I suspect the issue of time in type and checkout 

requirements vary considerably from one insurance 

company to another.  I have found the EAA 

arranged coverage seems to fit recreational 

flying well while insurance packages arranged for 

more conventional airplane owners have a 

completely different set of requirements.  Lets 

face it - people have a very hard time finding 

experimental airplanes to get dual instruction 

in, but those who buy Cessnas can get dual time at nearly any local airport.



Paul

XL  fuselage

At 08:12 AM 3/12/2008, you wrote:

[quote]I too bought the kit before the first major 

failure.  I held off building the wings until last.



Common sense would tell you to fly this aircraft 

in the Normal category until more facts are in.



Explosions of header fuel tanks, be they 8 

gallons or 1 gallon can lead directly to spar 

failure and wing fold in any design.



An ejector canopy with a pilot parachute are an 

inexpensive option, just make sure you have room to duck.



Engine vibration due to plug fouling can lead to 

an increased load on the airframe.  Compare the 

XL O-200A engine mount with the Cessna 150 mount.



Looking at XLs over the years, one notices the following:



Failure to twist the ailerons 2.5 degrees. (6-W-2)



Evidence of excessive flexing due to wind damage 

at the top of the aileron,  inboard attach point.



Failure to include an upper elevator stop (the 

shoe is often beyond 32 degrees). (6-S-4)



Failure to center the flaps on the rear spar, 

they often rise too far above or are set too far below the spar. (6-W-00)



Drilling too large of an aileron control rod 

hole, or placing it too low in the rear spar near rib 7. (6-W-00)



Not having dL = dR (6-S-3).   In light of recent 

events there is no excuse for being anywhere 

near the +/- 50 mm tolerance allowed by the designer.



Failure to properly attach the rear spars 

including failure to set the top aft edge of 

both to an equal distance below the longeron 

reference line; improper use of shims between 

the 6B5-4 attach plate and the rear spar; the 

rear spar mounted on the wrong side of the attach plate. (6-S-3)



Fly the factory Zenith, see how much       Be a better friend, newshound, and   [quote][b]

craig(at)craigandjean.com
Guest

Posted: Thu Mar 13, 2008 2:55 pm Post subject: Accident

 	  Quote: 	
		   looping XL video on its company web page  

Where is it on the ZAC site?  

-- Craig  

From: owner-zenith-list-server(at)matronics.com [mailto:owner-zenith-list-server(at)matronics.com] On Behalf Of David Downey

 Sent: Thursday, March 13, 2008 4:23 PM

 To: zenith-list(at)matronics.com

 Subject: Re: Re: Accident  

Hi Paul;

 I believe the reference to centering the flaps is related to the thickness of the flap being considerably over the thickness of the contour of the wing airfoil immediately ahead of the retracted flap (about 0.240"). The referenced drawing calls for the 3 mm above local contour and 3mm below local contour - centered.

 As for the aerobatic flight reference, why do you think Zenith keeps the looping XL video on its company web page? Many pilots do not have an understanding of the rate of acceleration that occurs when a maneuver is botched - I almost pulled the wings off a 150 back in 1976 when I screwed up a solo departure stall. All I remember was the engine screaming and the ASI pegged with the VSI going around like a clock spring unwinding...I had a new instructor the next flight!

 Paul Mulwitz <psm(at)att.net> wrote:  

--> Zenith-List message posted by: Paul Mulwitz 

 Hi Sabrina,

 Thanks for all the interesting comments. Let me 

 add a few questions and answers of my own.

 The XL doesn't have a header tank. All the fuel is stored in the wing tanks.

 I don't understand your comment about Normal 

 category flight. The XL is not designed for aerobatic flight.

 I would like more information on your ejector 

 canopy. I think a personal parachute would be a 

 wise thing to have - especially for initial 

 flight testing. However, I don't know of any 

 technique for bailing out of a plane with a front 

 hinged canopy. Detailed design information would 

 be greatly appreciated. I actually asked 

 Sebastian Heintz about this before starting 

 building my XL. He made a joke about it and said 

 the "Egress system has not been tested" or some such cute remark.

 I think the aileron twist is done to give the 

 wing some washout. This makes the stall take 

 place at the root before the tips and allows for 

 better control during a stall. I don't think the 

 twist has much of any other impact.

 I don't understand you comment about centering 

 the flaps on the rear spar. The flaps are 

 mounted on the bottom flange of the spar. How could they be centered?

 I just got a phone quote from Falcon insurance 

 for EAA coverage of my XL. They said the price 

 for liability would be around $600 per 

 year. Hull insurance varied from around $700 for 

 non-flying coverage to around $2100 for full hull 

 coverage. The hull quotes were based on a 

 $50,0000 value for the plane. The broker I spoke 

 to seemed to think the Zodiac was a fine 

 experimental plane, and also said the companies 

 he uses for EAA coverage don't distinguish 

 between a private pilot flying with full 

 privileges or one limited to Sport Pilot 

 privileges - the premiums are the same. As to 

 pilot experience, he said a couple of hours (yes 

 2) in type would be helpful. Oddly, he said in 

 my case (Sport Pilot limited private pilot) my 

 wife could be covered as a student pilot only if 

 she was training for a Private Pilot license 

 rather than a Sport Pilot license. This 

 restriction applied to only one of the two 

 insurance companies he uses (I think it was AIG)

 I suspect the issue of time in type and checkout 

 requirements vary considerably from one insurance 

 company to another. I have found the EAA 

 arranged coverage seems to fit recreational 

 flying well while insurance packages arranged for 

 more conventional airplane owners have a 

 completely different set of requirements. Lets 

 face it - people have a very hard time finding 

 experimental airplanes to get dual instruction 

 in, but those who buy Cessnas can get dual time at nearly any local airport.

 Paul

 XL fuselage

 At 08:12 AM 3/12/2008, you wrote:

 >I too bought the kit before the first major 

 >failure. I held off building the wings until last.

 >

 >Common sense would tell you to fly this aircraft 

 >in the Normal category until more facts are in.

 >

 >Explosions of header fuel tanks, be they 8 

 >gallons or 1 gallon can lead directly to spar 

 >failure and wing fold in any design.

 >

 >An ejector canopy with a pilot parachute are an 

 >inexpensive option, just make sure you have room to duck.

 >

 >Engine vibration due to plug fouling can lead to 

 >an increased load on the airframe. Compare the 

 >XL O-200A engine mount with the Cessna 150 mount.

 >

 >Looking at XLs over the years, one notices the following:

 >

 >Failure to twist the ailerons 2.5 degrees. (6-W-2)

 >

 >Evidence of excessive flexing due to wind damage 

 >at the top of the aileron, inboard attach point.

 >

 >Failure to include an upper elevator stop (the 

 >shoe is often beyond 32 degrees). (6-S-4)

 >

 >Failure to center the flaps on the rear spar, 

 >they often rise too far above or are set too far below the spar. (6-W-00)

 >

 >Drilling too large of an aileron control rod 

 >hole, or placing it too low in the rear spar near rib 7. (6-W-00)

 >

 >Not having dL = dR (6-S-3). In light of recent 

 >events there is no excuse for being anywhere 

 >near the +/- 50 mm tolerance allowed by the designer.

 >

 >Failure to properly attach the rear spars 

 >including failure to set the top aft edge of 

 >both to an equal distance below the longeron 

 >reference line; improper use of shims between 

 >the 6B5-4 attach plate and the rear spar; the 

 >rear spar mounted on the wrong side of the attach plate. (6-S-3)

 >

 >Fly the factory Zenith, see how much       

Be a better friend, newshound, and    	  Quote: 	
		    http://www.matronics.com/Navigator?Zenith-List 	
0 	  Quote: 	

1 	  Quote: 	

2 	  Quote: 	

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       [quote][b]

zodierocket(at)hsfx.ca
Guest

Posted: Thu Mar 13, 2008 4:42 pm Post subject: Accident

Hello Again Listers, below are some words from Chris Heintz on the last flurry of this discussion, at the bottom of this letter is the whole letter from May 10 2007.   

Special note to Zodiac Pilots: The Zodiac aircraft has a large amount of elevator control. I designed this feature so that if a pilot improperly computes the C of G before flying, he/she will in most cases have enough elevator authority to safely return and land. Also, like most of my other aircraft designs, the Zodiac has excellent control authority at low speeds. It is critical that this extra controllability not be abused. Pushing the stick rapidly full forward at cruise speed - even briefly - can result in serious damage to the airframe. Caution must be exercised to not inadvertently push the stick rapidly to its limits ( i.e. while stretching, reaching into the rear baggage compartment, etc.). Remember also that, without a doubt, you will always have a more enjoyable flight if the weather is "severe clear".  

Owners should take note that the CH601XL has relatively light pitch control forces and that it is possible to exceed the positive (+6) and the negative (-3) ultimate load factors if forcing the controls in a very rough or sudden manner.  Please be reasonable: the fact that the CH601XL can perform aerobatic maneuvers very well does not make it an aerobatic design."  

So this latest spawn of doubt sprang from someone stating that the Aussie accident had a wing failure, then the band wagon was lead by the loudest voice. I have no problem with a common sense discussion of the 601’s design. Hell that is what this list is for, in Chris’s own words the control of the elevator can move the plane into stresses that can exceed it’s design. I am concerned about the mentality that wishes to believe a problem exists without proof and runs with heresay.  

   

So lets get back to the latest one in Australia, I have just gotten off the phone from the Dealer there and had a discussion with them and the divers who found the wreckage. I cannot tell you what happened, nor am I going to guess. I will not judge accomplished pilots and builders of the plane. I have not talked to Zenith about this so the information I have is from non official sources. However, I will lay out the facts here as I know them to be from people who are there and seen the wreckage.  

   

<![if !supportLists]>1.       <![endif]>Parts of the Canopy have been found 2 kms from the resting location of the plane. Some have been found on top of buildings.  

<![if !supportLists]>2.       <![endif]>Pictures taken with camera’s were deceiving at first by hiding one side of the fuselage on decent, but some frames have shown the plane just before impact with the water and both wings are in place, as well as the tail. The divers that found the wreakage have stated that all flying surfaces are attached to the plane, though the canopy is missing.  

<![if !supportLists]>3.       <![endif]>The shape of the pilots looks to be a quick and merciful by the report of one diver.  

<![if !supportLists]>4.       <![endif]>There is a report of pelicans that fly in that area, that is a large bird.  

   

Accidents unfortunately can happen, we have weather, objects, mechanical failures, pilot issues, running out of gas and stresses placed on the planes beyond design loads. As improperly executed Aerobatics can do or sudden full stop inputs on the controls.  

   

I am not saying to stop what your doing, it is your choice, discuss your options. But be realistic, consider your opinion before placing it on this list for the Archives to capture. This accident is unfortunate but in no way is there any evidence of a structural issue, just the opposite, the plane may have flown 2 kms with no one at the controls. I do not know but the broken canopy may indicate such.   

     

Mark Townsend  

Can-Zac Aviation Ltd.  

president(at)can-zacaviation.com (president(at)can-zacaviation.com)  

www.can-zacaviation.com   

  

   

[img]cid:image001.jpg(at)01C88549.E2D02DE0[/img]                                                    <![endif]--><![if !vml]>[img]cid:image001.jpg(at)01C88549.E2D02DE0[/img]<![endif]>Letter from Chris Heintz  

May 10, 2007:    

As the designer of the Zodiac CH 601 series of aircraft, I take it very personally when I hear of a fatal accident involving one of these aircraft, especially when it involves elements of an in-flight break up.   

With the introduction of the Light Sport Aircraft rule, I personally re-calculated the entire Zodiac CH 601 XL design to confirm that it exceeded all minimum LSA design requirements. The structure of the design is comparable to the Alarus CH2000 FAR 23 certified aircraft (now certified in more than 20 countries). The present Zodiac XL S-LSA model is stressed to an ultimate +6/-3 g at 1,320 lbs.  

Still, we have seen a disturbing number of accidents over the last year, including the most recent one on May 2, 2007 (NTSB Identification: DFW07LA102). Having evaluated the wreckage photos of a Zodiac crash in 2006, I am in the process of starting yet another complete set of structural load tests on a production airframe. This will be done at the Zenair Ltd factory in Canada. In order to make absolutely certain nothing is missed, an independent structural engineer will confirm the findings of these rigorous tests.  

[img]cid:image002.jpg(at)01C88549.E2D02DE0[/img]  

 \n\u003cp style\u003d\"color:rgb(51,51,255)\"\>\u003cfont color\u003d\"#009900\"\>While I am confident that the Zodiac XL design will again be found to be sound in every respect, it is important for builders and pilots of this very nice airplane to have full confidence in the integrity of the aircraft. Findings of the tests will be communicated through the Zenair Newsletter and through the Zenith Aircraft website.\n\u003c/font\>\u003c/p\>\u003c/span\>",1] );  //--> While I remain fully confident that my Zodiac XL design will again be found to be sound in every respect, it is important for builders and pilots of this popular airplane to have full confidence in the integrity of the aircraft. Findings of the tests will be communicated through this website.  

[img]cid:image003.jpg(at)01C88549.E2D02DE0[/img]  

 \u003cfont color\u003d\"#009900\"\>\u003cspan style\u003d\"text-decoration:underline\"\>Special note to Zodiac Pilots\u003c/span\>: The Zodiac aircraft has a tremendous amount of elevator control. I designed this feature so that if a pilot improperly computes the C of G before flying, he/she will in most cases have enough elevator authority to safely return and land. Also, like?most?of my other aircraft designs, the Zodiac has excellent control authority?at low speeds. It is critical that this extra controllability not be abused. Pushing the stick rapidly full forward at cruise speed - even for a second - can result in serious damage to the airframe and pilot(s). Caution must be exercised to not inadvertently push the stick to its limits (\ni.e. while stretching or reaching into the rear baggage compartment); Also, slow down if flying in turbulent weather where bumps could cause your control arm to move, thereby moving the stick in an unwanted way? ?\u003c/font\>\u003c/p\>\n\n\u003cp style\u003d\"color:rgb(51,51,255)\"\>\u003cfont color\u003d\"#009900\"\>Please continue to be safety-conscious whenever you fly\u003c/font\>\u003cfont color\u003d\"#009900\"\>. Always stay within the design limits of your aircraft and well within your own abilities as a pilot. \n\u003c/font\>\u003cspan style\u003d\"color:rgb(51,51,255)\"\>\u003cfont color\u003d\"#009900\"\>CH\u003c/font\>\u003c/span\>\u003c/p\>\n\u003cp\>\u003cspan style\u003d\"color:rgb(51,51,255)\"\>\u003cfont color\u003d\"#009900\"\>\u003cu\>A \u003c/u\>\u003cu\>Note from Zenith Aircraft Co.:\u003c/u\> We are happy to report that our red and white factory demo Zodiac XL (N-601XK) is now six?years old! This Jabiru-powered aircraft?has logged over 1,100 hours (as of?April 2007) and has crisscrossed the USA dozens of times in all kinds of conditions. We estimate that we fly over 300 demo flights per year in this aircraft; that's over 1,800 passengers over the last 6 years. Additionally, over 15,000 people have taken a seat in this aircraft over the years at different shows and fly-ins, as well as at the factory. The plane flies as well today as it did when it was new; we feel very fortunate being the kit manufacturer for such a fine aircraft.?The fact that?our demo?plane still looks and performs as well as it does is a testament to the design's integrity?and robustness. If you have not done so already, call us today to schedule your own demo flight in 601XK!?ZAC\n",1] );  //--> Special note to Zodiac Pilots: The Zodiac aircraft has a large amount of elevator control. I designed this feature so that if a pilot improperly computes the C of G before flying, he/she will in most cases have enough elevator authority to safely return and land. Also, like most of my other aircraft designs, the Zodiac has excellent control authority at low speeds. It is critical that this extra controllability not be abused. Pushing the stick rapidly full forward at cruise speed - even briefly - can result in serious damage to the airframe. Caution must be exercised to not inadvertently push the stick rapidly to its limits ( i.e. while stretching, reaching into the rear baggage compartment, etc.). Remember also that, without a doubt, you will always have a more enjoyable flight if the weather is "severe clear".  

Please continue to be safety-conscious whenever you fly. Always stay within the design limits of your aircraft and well within your own abilities as  the pilot in command.  

Chris Heintz.      

    Update: Photos of      structural load testing performed by Zenair Ltd. (photos      posted on June 18, 2007).        

  

Update from Chris (July 2007):  

"To 'certify' the CH601XL in the LSA category, a complete stress analysis was performed and confirmed for the positive loads be static tests. No permanent deformations were found at limit loads (i.e. +4 'g') and no failures at ultimate loads (i.e. +6 'g').  The bending deformations were in accordance with the analysis and the torsional deformations were barely measurable, removing the possibility wing or tail flutter.  

[img]cid:image004.jpg(at)01C88549.E2D02DE0[/img]

 Load testing the Zodiac XL by Zenair Ltd. (June 16, 2007)  

"Recently, Zenair Ltd. also performed static tests of the negative loads on the wing, fuselage and horizontal tail (see photos) and the results were similar to the positive load tests: No permanent deformation at limit loads and no failure at ultimate 'g' loading.  The bending and torsional deformations were very small (the torsional twist was practically zero!).  

"I want to remind and reassure every owner, builder  that not\n                  only is the\u003cspan style\u003d\"color:rgb(51, 0, 51)\"\> \u003cspan style\u003d\"background-color:rgb(102, 255, 153)\"\>main \u003c/span\>\u003c/span\>structure \u003cspan style\u003d\"background-color:rgb(102, 255, 153)\"\>well in compliance \u003c/span\>\n\u003cspan style\u003d\"background-color:rgb(255, 102, 0)\"\>substantiated\u003c/span\> with the ASTM standards,\n                  but also\u003cspan style\u003d\"background-color:rgb(102, 255, 153)\"\>, \u003c/span\>\u003cspan style\u003d\"background-color:rgb(255, 102, 0)\"\>the \u003c/span\>'accessories' such as the seat\u003cspan style\u003d\"background-color:rgb(102, 255, 153)\"\>\n-\u003c/span\>belt attachments,\n                  battery installation, etc... were all static tested with\n                  \u003cspan style\u003d\"background-color:rgb(102, 255, 153)\"\>very \u003c/span\>satisfactory results. \u003cbr\>\u003c/font\>\u003c/p\>\u003cp align\u003d\"left\"\>\u003cfont face\u003d\"Arial\"\> Owners should take note that the\n                  CH601XL has relatively light pitch control forces and \u003cspan style\u003d\"background-color:rgb(102, 255, 153)\"\>that \u003c/span\>it is\n                  possible to exceed the positive (+6) and the negative (-3)\n                  ultimate load factors if forcing the controls in a very rough\n                  or sudden manner.? Please be reasonable: \u003cspan style\u003d\"background-color:rgb(255, 102, 0)\"\>in spite of\u003c/span\> the\n                  fact that the CH601XL can perform aerobatic maneuvers very\n                  well does \u003cu\>not\u003c/u\> make it an aerobatic design."\u003c/font\>\u003c/p\>\n      \u003c/blockquote\>\u003cbr\>\u003cbr\>\u003cbr\>\u003cbr\>\u003cdiv\>",1] );  //--> and pilot that not only is the main structure well in compliance with the ASTM standards, but also,  'accessories' such as the seat -belt attachments, battery installation, etc... were all static tested with very satisfactory results.  

Owners should take note that the CH601XL has relatively light pitch control forces and that it is possible to exceed the positive (+6) and the negative (-3) ultimate load factors if forcing the controls in a very rough or sudden manner.  Please be reasonable: the fact that the CH601XL can perform aerobatic maneuvers very well does not make it an aerobatic design."      

  

A Brief Note from Zenith Aircraft Company: 

 

 We are pleased to report that our red and white factory demonstrator Zodiac XL (N9601Z) is now six years old and has logged over 1,000 hours.  The aircraft has crisscrossed the United States dozens of times through all kinds of conditions. We fly well over 300 demo flights per year in this aircraft; that's over 1,800 passengers over the last 6 years. Additionally, over 15,000 people have taken a seat in this aircraft over the years at different shows and fly-ins, as well as at the factory. The plane flies as well today as it did when it was new; we feel very fortunate being the kit manufacturer for such a fine aircraft. The fact that our demo plane still looks and performs as well as it does is a testament to the design's integrity and robustness.

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steveadams

Joined: 10 Jan 2006
Posts: 191

Posted: Fri Mar 14, 2008 1:32 am Post subject: Re: Accident

Hey, when it comes to something like this, do the armchair designers really want the truth, or would they rather cling to their preconceived notions? It doesn't matter that the wings showed almost no torsion at all and no failure at the ultimate load in testing or that the latest accident was not a structural failure. The notion that there is a problem has taken a life of its own regardless of fact or reason. I am in awe that someone is so good they can even design a fix to correct an imaginary problem.

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