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All 601XL grounded in Netherlands
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David X

Joined: 10 Jan 2006
Posts: 154
Location: Princeton, NJ, USA

Posted: Fri Nov 14, 2008 4:26 pm Post subject: All 601XL grounded in Netherlands

My purpose in posting this is to make information available to builders and owners. This may affect your periodic or annual inspection. Attention should be given to the wing rear attach points at the wing root and the cable tensions, particularly the ailerons.



I am not speculating, but simply conveying what I was told over the phone by the FAA and NTSB. I'm conveying this in my own words. Nothing in this post are official NTSB findings.



I received two calls today, one from the FAA and another from the NTSB. They wanted me to be aware of the grounding of all 601XL in Netherlands. The aircraft in question was built by Czech Aircraft Works. There are perhaps 2 in the US that were build by CZAW. One was crashed by my friend in Virginia (the NTSB preliminary report indicated that there was no fuel in the wing tanks, fuel lines or carburetor bowls). I own the only remaining 601XL in the US built by CZAW.



The issues of concern that were conveyed to me by the FAA and NTSB were aileron flutter (NTSB) and wing folding (FAA). There has not been a conclusion by the NTSB regarding the wing folding incidents. The aileron flutter is a point of interest but it is not known whether it is a factor in the Dutch crash. Although your aircraft was probably not built by CZAW, I think the information would apply to the 601XL design in general.



The thought/concern conveyed to me is that a flutter condition could cause a wing failure if torsional (twisting) forces were high enough. The main spar was not designed to withstand torsional forces and depends on the rear wing mounts to prevent twisting. 



This is not something unique to the 601XL but a possible condition in any aircraft with unbalanced control surfaces. By unbalanced, I mean that there is no counter-weight in aileron, elevator or rudder to keep them in a neutral position absent any outside force (such as air flow or control inputs). The 601XL does not exhibit flutter so long as the cable tensions are correct. There is also a very generous margin +/- 5 lbs. 



I was told that the engineers at the NTSB have reviewed the 601XL design and by all indications it is a 6G aircraft (theoretical) and is as advertised by the designer. Of course, it is rated much lower for margin of safety. I was told that there were no major concerns about the design. The potential for flutter seemed to be their main focus. 



The only other information I was given was to make sure that the POH had the correct calibrated air speeds. Calibrated speeds are preferred over indicated (the latter varying depending on density altitude, temperature and altitude).



I have flown my 601XL for 300+ hours. I also flew it coast to coast over the Rockies twice and I have had zero issues whatsoever with aileron flutter. Years ago, after hearing about the wing folding incidents, I spot painted the the rear spar connection points and the main spar attach points as a way to detect any shift. I have seen zero shift in 3 years of flying.



Linked below are service bulletins issued by Dutch and AMD that apply to this particular situation. I've included a few links that speak to this situation.



http://www.zenairulm.com/News/pdfdocs/ZE-2008-01.pdf 



http://www.newplane.com/Service_Letters_Bulletines/SAFETY_ALERT_october_29_2008.pdf 



http://www.zenairulm.com/News/index_files/Page349.htm



http://www.zenairulm.com/News/index_files/Page350.htm

_________________
Zodiac 601 XL - CZAW Built - Rotax 912S
DO NOT ARCHIVE

Last edited by David X on Fri Nov 14, 2008 10:31 pm; edited 6 times in total

craig(at)craigandjean.com
Guest

Posted: Fri Nov 14, 2008 5:11 pm Post subject: All 601XL grounded in Belgium

"There are perhaps 2 in the US that were build by CZAW."



I thought that the Xl that went down in Florida near Sun-n-fun was also a

CZAW plane?



NTSB:



<quote>

NTSB Identification: NYC08FA158

Accident occurred Monday, April 07, 2008 in Polk City, FL

Aircraft: Chech Aircraft Works SPOL SRO CH 601 XL RTF, registration: N357DT

Injuries: 1 Fatal.



This is preliminary information, subject to change, and may contain errors.

Any errors in this report will be corrected when the final report has been

completed.



On April 7, 2008 about 1700 eastern daylight time, a Czech Aircraft Works

SPOL SRO CH 601 XL RTF, N357DT, was substantially damaged when it impacted

trees and terrain following an uncontrolled descent near Polk City, Florida.

<endquote>



FAA database:



N357DT is Assigned



Aircraft Description



Serial Number	   	6-9733 	           	Type Registration

Individual

Manufacturer Name 		CZECH AIRCRAFT WORKS SPOL SRO

Certificate Issue Date 		11/28/2007

Model		CH 601 XL RTF 		Status 		Valid

Type Aircraft 		Fixed Wing Single-Engine 		Type Engine

Reciprocating

Pending Number Change		None 		Dealer		No

Date Change Authorized		None 		Mode S Code

50777453

MFR Year 		2005 		Fractional Owner 		NO



-- Craig

David X

Joined: 10 Jan 2006
Posts: 154
Location: Princeton, NJ, USA

Posted: Fri Nov 14, 2008 6:32 pm Post subject: Re: All 601XL grounded in Belgium

I recall that there was a 3rd, but the NTSB seems to be under the impression that there were only two. Thank you for the info. I'll pass it along.

_________________
Zodiac 601 XL - CZAW Built - Rotax 912S
DO NOT ARCHIVE

David X

Joined: 10 Jan 2006
Posts: 154
Location: Princeton, NJ, USA

Posted: Fri Nov 14, 2008 10:33 pm Post subject: Re: All 601XL grounded in Netherlands

To anyone who read this post before I edited it ... the country in question is the Netherlands, not Belgium.

_________________
Zodiac 601 XL - CZAW Built - Rotax 912S
DO NOT ARCHIVE

aerobat

Joined: 07 Nov 2008
Posts: 21
Location: UK

Posted: Sat Nov 15, 2008 5:36 am Post subject: Re: All 601XL grounded in Netherlands

The aircraft is grounded by most European countries now, here in the UK about two dozen are affected.

craig(at)craigandjean.com
Guest

Posted: Sat Nov 15, 2008 8:14 am Post subject: All 601XL grounded in Netherlands

As I understand it the XL was grounded in the UK due to worries about the

cable AD, not the Dutch action. What will the UK authorities do to decide

whether to let them fly again? 



-- Craig



Do not archive



--

Gig Giacona

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

Posted: Sat Nov 15, 2008 10:39 am Post subject: Re: All 601XL grounded in Netherlands

David, I curious. Did they call you because you had a CZAW built aircraft?

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

chris Sinfield

Joined: 28 Nov 2006
Posts: 270
Location: Sydney Australia

Posted: Sat Nov 15, 2008 8:34 pm Post subject: Re: All 601XL NOT grounded in Australia

Some good news

in Australia the RAA has not grounded any XL's there is 1imported CZAW built aircraft and the rest are by zenith kits. We have a good Zenith XL network and he was notified of the aileron tension issues and checked his A/C. yes his cables were about 1/2 of what they should be. of note he  had no flutter issues before with the lower tensions. 



The RAA here are happy with us having the SB in our XL newsletter, the remainder of us are all builders of XL those finished and those still going. we built it we should know how to check it, maintain it.



Common sense to the RAA.

Chris.

Sydney

XL Jab3300

Jugle

Joined: 04 Aug 2007
Posts: 47
Location: Victoria, Australia

Posted: Sun Nov 16, 2008 2:59 pm Post subject: Re: All 601XL grounded in Netherlands

Can someone please clarify?



As I understand it the CZAW 601s have a lower MTOW and are built from lighter material in some areas, correct?



So, obviously the cable tensions need to be correct regardless, but does this mean the CZAW versions are more susceptible to the problem?



Glenn.

_________________
Glenn Andressen
601XL- Rudder, Stabiliser parts completed, Wing ribs, nose ribs done, 70% Fuselage parts made.

larry(at)macsmachine.com
Guest

Posted: Sun Nov 16, 2008 4:10 pm Post subject: All 601XL grounded in Netherlands

Glenn,

You are correct about the materials and MTOW, so would it not be more a 

risk to those who would load to US standards by mistake or assume the 

aircraft

to be the same after the fact.  This would be easier to understand if 

they used Internet to read Zenith specifications. The casual thought that

these aircraft were the same construction might be a dangerous one for 

the European built and Mfg aircraft.



Doubt cable tensions had anything to do with the problems nor a solution 

for the problems of concern either.



Larry McFarland 601HDS at www.macsmachine.com



Jugle wrote:

 	  Quote: 	
		   



 Can someone please clarify?



 As I understand it the CZAW 601s have a lower MTOW and are built from lighter material in some areas, correct?



 So, obviously the cable tensions need to be correct regardless, but does this mean the CZAW versions are more susceptible to the problem?



 Glenn.



 --------

 Glenn Andressen

 601XL- Rudder, Stabiliser partially completed, Wing   ribs, nose ribs done, numerous other parts made.

Terry Phillips

Joined: 11 Jan 2006
Posts: 346
Location: Corvallis, MT

Posted: Sun Nov 16, 2008 6:01 pm Post subject: All 601XL grounded in Netherlands

Glenn



You are right. CZAW 601XL's are lighter. But, they are lighter in only one 

place: The landing gear.



CZAW used the composite gear sold by Aircraft Spruce. The Aircraft Spruce 

landing gear is limited to 550 kg gross, which is less than the Zenair 600 

kg (1320 lb) gross. However, I believe that some of the CZAW 601XL's that 

made it to the US were registered with 600 kg gross. See:



http://www.aircraftspruce.com/catalog/lgpages/compositelg.php



Other than that, CZAW 601XL's are identical or even beefed up a bit 

compared to the standard Zenair 601XL. I believe that all CZAW 601XL's use 

the piano hinged aileron and incorporate the electric aileron trim option. 

In fact, I believe that if you check with someone who owns a CZAW 601XL, 

you'll find that the aileron piano hinge has been beefed up beyond the 

standard Zenair piano hinge.



So, if the cable tension is more critical for the CZAW built 601XL's than 

for the Zenair 601XL's (personally, I do not believe that it is), the 

difference would evidently lie in the hinges or the trim option. (Note that 

not all Zenair 601XL's have piano hinges or aileron trim tabs, while all 

CZAW 601XL's apparently have those options.)



Terry

At 02:59 PM 11/16/2008 -0800, you wrote:

 	  Quote: 	
		  Can someone please clarify?



As I understand it the CZAW 601s have a lower MTOW and are built from 

lighter material in some areas, correct?



So, obviously the cable tensions need to be correct regardless, but does 

this mean the CZAW versions are more susceptible to the problem?



Glenn


	




Terry Phillips  ZBAGer

ttp44~at~rkymtn.net

Corvallis MT

601XL/Jab 3300 s .. l .. o .. o .. w build kit - Tail, flaps, & ailerons 

are done; working on the wings

http://www.mykitlog.com/N47TP/

_________________
Terry Phillips
Corvallis, MT
ttp44<at>rkymtn.net
Zenith 601XL/Jab 3300 slow build kit - Tail feathers done; working on the wings.

alex_001

Joined: 14 Jan 2007
Posts: 61

Posted: Mon Nov 17, 2008 1:14 am Post subject: Re: All 601XL grounded in Netherlands

I would like to point out that the 601xl that went down in the Netherlands was not a RTF CZAW it was a kit build (Kit was supplied by CZAW)

tiethoff

Joined: 02 Sep 2008
Posts: 23

Posted: Mon Nov 17, 2008 7:46 am Post subject: All 601XL grounded in Netherlands

CZAW XL's are lighter because the undercarriage gear is made out of carbon. 

That's the ONLY difference. On some 601's flying in Europe the part of the 

wing where you put your feet (on the black anti slip pieces) is a half 

milimeter thicker. On each wing 40  x 80 cm.



Regards, Eric Tiethoff

The Netherlands.



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

From: "Jugle" <glenn(at)eastcoastit.net>

Sent: Sunday, November 16, 2008 11:59 PM

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

Subject: Re: All 601XL grounded in Netherlands



 	  Quote: 	
		   



 Can someone please clarify?



 As I understand it the CZAW 601s have a lower MTOW and are built from 

 lighter material in some areas, correct?



 So, obviously the cable tensions need to be correct regardless, but does 

 this mean the CZAW versions are more susceptible to the problem?



 Glenn.



 --------

 Glenn Andressen

 601XL- Rudder, Stabiliser partially completed, Wing   ribs, nose ribs 

 done, numerous other parts made.





 Read this topic online here:



 http://forums.matronics.com/viewtopic.php?p 14595#214595

alex_001

Joined: 14 Jan 2007
Posts: 61

Posted: Mon Nov 17, 2008 8:13 am Post subject: Re: All 601XL grounded in Netherlands

I have a little dent in my LH aileron ruder at the hinge area.

can someone give my advise if i should worry or if this could be caused by "flutter"



thank you

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alex_001

Joined: 14 Jan 2007
Posts: 61

Posted: Mon Nov 17, 2008 8:47 am Post subject: Re: All 601XL grounded in Netherlands

Sabrina,

i send my pics to Michael H. and waiting for answer.

this 601xl is always kept in hangar and has about 70hrs



on a other issue i fitted some wing root fairings from Zenair in France looks real cool

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alex_001

Joined: 14 Jan 2007
Posts: 61

Posted: Mon Nov 17, 2008 8:57 am Post subject: Re: All 601XL grounded in Netherlands

Sabrina,



on my friends 601xl (RTF CZAW) this plane was a former display plane at the Friedrichshafen Air Show in 2005 after the show the plane went back to CZAW, to have on the area where you have the anti slip tape on the top of the wing a 2nd skin riveted on  the reason for this was during the exhibition so many people climbed in and out of the plane (also some females with pointed heels) that the skin was a bit sad to look at. And therefore CZAW riveted a 2nd skin over it (but i am not sure in what gauge) but this was ONLY to cover the dents that came from climbed show.

Terry Phillips

Joined: 11 Jan 2006
Posts: 346
Location: Corvallis, MT

Posted: Mon Nov 17, 2008 9:16 am Post subject: All 601XL grounded in Netherlands

Very good point, Sabrina. and a very interesting photo. 



 I wasn't aware of Alex's photo. Where did you find it, BTW? My search fails me in trying to locate it. Alex's photo points out a good example of a CZAW "beef up," i.e., the diagonal bracing in the fuselage side panels. I don't recall seeing that in my B-23. I believe that ZAC did copy that feature in the 650. It is probably a good idea and I will probably add it to my 601XL.



 Regarding the skin thickness, one must also be aware that CH's designs also change over the years. Fortunately, ZAC has documented these changes on their website. See, e.g.,



 http://www.zenithair.com/zodiac/xl/data/xl-update-3rd-ed-1st-rev-4-05.pdf



 where you find the following:



 6-B-3 04/05 REAR SIDE SKINS

 1) new page layout: Moved 6B3-3 and 6B3-4 to drawing 6-B-1 (01/05)

 2) 6B3-1 Rev. 2 change material thickness from t=.016” to t=.025” (12/04)

 3) 6B3-2 deleted battery access option (area is now accessible through bottom access

 panel) (12/04)

 4) 6B3-6 Rev 1 new width at front and rear, changed 67 to 61 , 251 to 272mm (03/05)

 5) New parts 6B3-7 and 6B3-8 piano hinge and bottom fuselage access panel. (12/04)

 6) Re-positioned 6B1-7 between the Z and 6B5-2 (12/04)

 note: the aft rivet line through the fairing 6G3-2 is the same rivet line through the piano

 hinge and Z angle.(12/04)

 7) Deleted Gusset 6B3-5 (01/05)

  Add nutplate 21075L3 (02/05)

 9) Added A4 pitch 20 bottom skin 6B1-4 into 6B1-1 (02/05)

 10) middle diagram: 340mm between rivets for the H.T frames (measured on center line)

 (03/05)

 11) top right diagram: riveting L angles to side skin 6B3-1 changed pitch from 60 to 40

 (04/05)



 Where I've colored item 2) to red for emphasis. 



 So, while I will readily agree with you that CZAW may have changed skin thicknesses, etc., over the years, I'm not yet ready to agree that their kit differs from ZAC except for the "beefing up" and the landing gear already cited. While their changes may (and I emphasize may because I don't have their design history) have lagged ZAC's would not be very suprising, because they would have had to react to whatever ZAC published.



 If you can show me examples of "light weight" CZAW designs, materials, etc., that differ from ZAC's designs, I'm ready to admit your point.



 Terry



 



 At 07:01 AM 11/17/2008 -0800, you wrote:

  	  Quote: 	
		  "But, they are lighter in only one place: The landing gear... Other than that, CZAW 601XL's are identical or even beefed up a bit compared to the standard Zenair 601XL. I believe"   Terry 



 Terry,



 Different CZAW 601XLs have different skin thicknesses, especially the kits as pointed out by Alex.    The attached photo is of an EU CZAW kit.  The QQ-A-250/11 does not designate a .025 skin, look up at the 0.016 in   



 6-B-3 08/05 specs .025 on the US version.   .025 is 56% more AL than .016, so our rear fuselage skins alone weigh 56% more than the CZAW kit.   



 The FAA reads this list, we can't keep telling them that the all CZAW 601XL are built "identical" or "beefed up" compared to our aircraft if it is not necessarily true.  They may start believing us. 	
 

 

 Terry Phillips  ZBAGer

 ttp44~at~rkymtn.net

 Corvallis MT

 601XL/Jab 3300 s .. l .. o .. o .. w build kit - Tail, flaps, & ailerons are done; working on the wings

 http://www.mykitlog.com/N47TP/     [quote][b]

_________________
Terry Phillips
Corvallis, MT
ttp44<at>rkymtn.net
Zenith 601XL/Jab 3300 slow build kit - Tail feathers done; working on the wings.

jaybannist(at)cs.com
Guest

Posted: Mon Nov 17, 2008 9:42 am Post subject: All 601XL grounded in Netherlands

Why is it that some of those, who know FOR SURE, swear that the European XLs are stronger and lighter than the US version; and others, who know FOR SURE, swear that the European XL is lighter and weaker than the US version; and still others, who know FOR SURE, swear that there is no difference? Someone, please 'splain how that can be to this poor ole country boy!  

 

 I AM just smart enough to know that all these positions (actually opinions) can't be true. I really hate to say it, but some of you either don't know what you are talking about, or you are lying, or both. Prove me wrong!

 

 Jay in Dallas

 Do not archive

 

   

 

   

 

 --

alex_001

Joined: 14 Jan 2007
Posts: 61

Posted: Mon Nov 17, 2008 9:45 am Post subject: Re: All 601XL grounded in Netherlands

the difference i think the 601xl from CZAW also have is that the angle of attack of the wing is flatter because CZAW only uses Rotax engine and that engine is less heavy and therefor less front heavy and less lift required and also more speed archieved . i been told this by chip erwin on my visit to the czaw factory.

psm(at)att.net
Guest

Posted: Mon Nov 17, 2008 9:57 am Post subject: All 601XL grounded in Netherlands

Hi Jay,



I agree with your question, but I would like to add another one.



How is it that the Dutch government has determined the design load 

calculations indicate an error on the designer's part but the 

Brittish government sees the same design as adequate?



I've been watching all these opinions by both qualified and 

unqualified people for years and still I believe we don't know 

anything at all about the structural failures.  There are, however, 

many people who are SURE they know what is wrong.



I am feeling good about Bill of Georgia's comments today about lose 

cables.  He is one of the people who have actually experienced the 

vibrations and survived.  His observation that his cables were loose 

suggests to me that we should all keep a close watch on those cables.



Paul

XL getting close

do not archive

At 09:42 AM 11/17/2008, you wrote:

 	  Quote: 	
		  Why is it that some of those, who know FOR SURE, swear that the 

European XLs are stronger and lighter than the US version; and 

others, who know FOR SURE, swear that the European XL is lighter and 

weaker than the US version; and still others, who know FOR SURE, 

swear that there is no difference? Someone, please 'splain how that 

can be to this poor ole country boy!



I AM just smart enough to know that all these positions (actually 

opinions) can't be true. I really hate to say it, but some of you 

either don't know what you are talking about, or you are lying, or 

both. Prove me wrong!



Jay in Dallas

Do not archive

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