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Undercarriage failures

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andrew.mcmenamin(at)xtra.
Guest

Posted: Sat Nov 27, 2010 11:11 pm Post subject: Undercarriage failures

Hi list members

  

 We have recently had both undercarriage legs  fail in quick succession.  We have an XL 601B with curved legs, which I  understand are made of carbon fibre covered with fibreglass, and after a firm  landing, noted on pre-flight a week later a 3 mm wide and 250 mm  long longitudinal crack down the midline of the rear aspect of the left  leg.  We had this replaced, then last week the other leg gave way after a  further firm landing, this time transversely across the upper leg just below the  attachment to the fuselage.

  

 These landings were just typical firm student  landings with an instructor and leg failure was not expected from  either.

  

 Has anyone had a similar experience? Any  recommendations?

  

 Thanks

  

 Andrew

   [quote][b]

Afterfxllc(at)aol.com
Guest

Posted: Sat Nov 27, 2010 11:41 pm Post subject: Undercarriage failures

Andrew,

 

 I have worked on the ones with the gear you mention and was warned by the owners that my test pilot had to be sure not to make any hard landings or the gear will crack.

 On the other hand the aluminum gear is about as robust as you can get as discovered in a forced landing. I would suspect that the landings were hard enough to crack the outer fiberglass and if it would have been the aluminum gear it would be a non issue. If this is a SLSA you might want to contact AMD or whom ever they are this month and see if you can convert it back to the heavier gear. IMHO I don't think the 50 or 60 lbs is worth the risk of a gear collapsing and really doing some damage.

 I also think all you have to do is replace the gear supports and the new larger gear still fits in the gear channel.

 

 Hope this helps

 Jeff [quote][b]

psm(at)att.net
Guest

Posted: Sun Nov 28, 2010 12:05 am Post subject: Undercarriage failures

Hi Andrew,

 

I don't really know what an XL 601B is.  

 

If you are using the light weight Czech gear on a 1320 pound plane then that might explain the gear failures.  I think the European Ultralight planes have a lower gross weight and the Czech gear was designed for that spec.

 

In any case going back to the standard aluminum "Spring" gear should solve your problem.

 

Paul

XL still doing the upgrade.

 

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

Sent: Saturday, November 27, 2010 10:40 PM

To: zenith601-list(at)matronics.com

Subject: Undercarriage failures

 

Hi list members



 



We have recently had both undercarriage legs fail in quick succession.  We have an XL 601B with curved legs, which I understand are made of carbon fibre covered with fibreglass, and after a firm landing, noted on pre-flight a week later a 3 mm wide and 250 mm long longitudinal crack down the midline of the rear aspect of the left leg.  We had this replaced, then last week the other leg gave way after a further firm landing, this time transversely across the upper leg just below the attachment to the fuselage.



 



These landings were just typical firm student landings with an instructor and leg failure was not expected from either.



 



Has anyone had a similar experience? Any recommendations?



 



Thanks



 



Andrew

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Afterfxllc(at)aol.com
Guest

Posted: Sun Nov 28, 2010 1:29 am Post subject: Undercarriage failures

Paul,

  

 AMD offered that gear as an option on the 601... I have one that came in  for a upgrade and I called Zenith to see if it was changed / illegal or factory  and sure enough it is an option.

  

 Jeff

  

  In a message dated 11/28/2010 3:06:23 A.M. Eastern Standard Time,  psm(at)att.net writes:

  	  Quote: 	
		        

Hi    Andrew,   

    

I    don't really know what an XL 601B is.     

    

If    you are using the light weight Czech gear on a 1320 pound plane then that    might explain the gear failures.  I think the European Ultralight planes    have a lower gross weight and the Czech gear was designed for that    spec.   

    

In    any case going back to the standard aluminum "Spring" gear should solve your    problem.   

    

Paul   

XL    still doing the upgrade.   

          

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

Sent: Saturday, November 27, 2010 10:40 PM

To:    zenith601-list(at)matronics.com

Subject: Undercarriage    failures



   

       

Hi list    members

      

 

      

We have recently    had both undercarriage legs fail in quick succession.  We have an XL    601B with curved legs, which I understand are made of carbon fibre covered    with fibreglass, and after a firm landing, noted on pre-flight a week later a    3 mm wide and 250 mm long longitudinal crack down the midline of the rear    aspect of the left leg.  We had this replaced, then last week the other    leg gave way after a further firm landing, this time transversely across the    upper leg just below the attachment to the    fuselage.

      

 

      

These landings were    just typical firm student landings with an instructor and leg failure was not    expected from either.

      

 

      

Has anyone had a    similar experience? Any recommendations?

      

 

      

Thanks

      

 

      

Andrew

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 [quote][b]

psm(at)att.net
Guest

Posted: Sun Nov 28, 2010 5:02 am Post subject: Undercarriage failures

Hi Jeff,

 

I guess that could be an example of the questionable engineering we have received from Zenith/Zenair/AMD.  It makes me all the more appreciative of the thousands of man-hours the FAA engineers spent reviewing the pre and post upgrade XL structure.

 

By the way, I confirmed the fact of all that FAA engineering effort with the manager of the light plane division - Wes Ryan.  I spoke with him while attending an ASTM F37 committee meeting a few weeks ago in Long Beach, CA.  He absolutely confirmed the facts that FAA engineers literally spent thousands of man-hours going over the XL design before the upgrade and again after the upgrade design was created by Zenair.  They indeed did pronounce the pre-upgrade design as deficient and the post-upgrade design as meeting the appropriate ASTM design requirements.

 

I think we are very lucky that the XL existed both in S-LSA form and kit/plans form.  If not for the S-LSA, I doubt the FAA would have paid so much attention to this design - even with the NTSB attention and accident record.  Now we have an apparently competent design for our planes.

 

Paul

Camas, WA

XL upgrade work in progress.

 

 

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

Sent: Sunday, November 28, 2010 1:27 AM

To: zenith601-list(at)matronics.com

Subject: Re: Undercarriage failures

 

Paul,



 



AMD offered that gear as an option on the 601... I have one that came in for a upgrade and I called Zenith to see if it was changed / illegal or factory and sure enough it is an option.



 



Jeff



 



In a message dated 11/28/2010 3:06:23 A.M. Eastern Standard Time, psm(at)att.net writes:

 	  Quote: 	
		  

Hi Andrew,

 

I don't really know what an XL 601B is.  

 

If you are using the light weight Czech gear on a 1320 pound plane then that might explain the gear failures.  I think the European Ultralight planes have a lower gross weight and the Czech gear was designed for that spec.

 

In any case going back to the standard aluminum "Spring" gear should solve your problem.

 

Paul

XL still doing the upgrade.

 

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

Sent: Saturday, November 27, 2010 10:40 PM

To: zenith601-list(at)matronics.com

Subject: Undercarriage failures

 

Hi list members



 



We have recently had both undercarriage legs fail in quick succession.  We have an XL 601B with curved legs, which I understand are made of carbon fibre covered with fibreglass, and after a firm landing, noted on pre-flight a week later a 3 mm wide and 250 mm long longitudinal crack down the midline of the rear aspect of the left leg.  We had this replaced, then last week the other leg gave way after a further firm landing, this time transversely across the upper leg just below the attachment to the fuselage.



 



These landings were just typical firm student landings with an instructor and leg failure was not expected from either.



 



Has anyone had a similar experience? Any recommendations?



 



Thanks



 



Andrew

 	  Quote: 	
		     www.aeroelectric.comwww.buildersbooks.comwww.homebuilthelp.comhttp://www.matronics.com/contributionhttp://www.matronics.com/Navigator?Zenith601-Listhttp://forums.matronics.com  	
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slook(at)mchsi.com
Guest

Posted: Sun Nov 28, 2010 9:44 am Post subject: Undercarriage failures

I thought this pot had been stirred enough. Apparently as long as Zenith survives or there is something more than scrap value left to the XL, there is never enough.



 Steve



 At 06:59 AM 11/28/2010, you wrote:

  	  Quote: 	
		   

 I guess that could be an example of the questionable engineering ... 	
 

 Steve Look

 Monticello, IL

 601XL

 "Dogs have owners, Cats have staff"    [quote][b]

bryanmmartin

Joined: 10 Jan 2006
Posts: 1018

Posted: Sun Nov 28, 2010 10:54 am Post subject: Undercarriage failures

I believe the composite gear was designed for the european version. The max gross weight is lower in the european rules. the composite gear was used to save weight and allow a greater usable payload but it is probably not as suitable as the original aluminum gear at the U. S. weight limits.



Two possible solutions to this are either order the original aluminum gear from Zenith or the lighter but more expensive gear from Grove. Both are stronger than the composite gear. Some modifications may be needed to the gear channel.



On Nov 28, 2010, at 1:40 AM, Andrew McMenamin wrote:



 	  Quote: 	
		   Hi list members

  

 We have recently had both undercarriage legs fail in quick succession.  We have an XL 601B with curved legs, which I understand are made of carbon fibre covered with fibreglass, and after a firm landing, noted on pre-flight a week later a 3 mm wide and 250 mm long longitudinal crack down the midline of the rear aspect of the left leg.  We had this replaced, then last week the other leg gave way after a further firm landing, this time transversely across the upper leg just below the attachment to the fuselage.

  

 These landings were just typical firm student landings with an instructor and leg failure was not expected from either.

  

 Has anyone had a similar experience? Any recommendations?

  


	


-- 

Bryan Martin

N61BM, CH 601 XL,

RAM Subaru, Stratus redrive.

do not archive.

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

psm(at)att.net
Guest

Posted: Sun Nov 28, 2010 11:13 am Post subject: Undercarriage failures

Steve,

 

Perhaps if you had read the rest of the message instead of just cutting it off you would reach a more correct conclusion.

 

I don't know why you want to bitch about Zenith surviving.  

 

The rest of the message should actually help the value of the XL since it says the new design has  actually proven to be a good one after extensive review by competent engineers rather then the poor one sold to us by Zenith/Zenair/AMD that wound up suffering a number of in-flight failures.

 

Or perhaps you are one of the folks who wants to believe there never was a real problem . . . that all those people died because they didn't keep their cables at the correct tension?

 

Just in case you actually read the end of messages as well as the first line . . . The Upgraded design is a competent one that meets the required ASTM standards according to the FAA engineers that do the part 23 reviews.  This was not true of the previous design.  We all were supposed to get that message from the FAA Special Airworthiness Information Bulletin issued last November, but the language was obscure enough that we just didn't understand what they were trying to say.   That was the document that required that ALL XLs and 650s receive the upgrade before being flown again.

 

Paul

 

 

 

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

Sent: Sunday, November 28, 2010 9:43 AM

To: zenith601-list(at)matronics.com

Subject: RE: Undercarriage failures

 

I thought this pot had been stirred enough. Apparently as long as Zenith survives or there is something more than scrap value left to the XL, there is never enough.



Steve



At 06:59 AM 11/28/2010, you wrote:

 

I guess that could be an example of the questionable engineering ...

Steve Look

Monticello, IL

601XL

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Terry Phillips

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

Posted: Sun Nov 28, 2010 11:37 am Post subject: Undercarriage failures

Hi Andrew



 Can you provide us with more information about your 601? It sounds like you are using it for flight instruction, so, I would assume, that it is a factory assembled S-LSA. Who built it? AMD, CZAW,  someone else? What is the gross weight limit specified in the POH? I believe that some CZAW 601XL's aircraft were manufactured for the European Ultralight specification with a maximum allowable gross of 472.5 kg (1042 lb). I know that Comlet, CZAW's landing gear supplier, markets versions of their gear for both 472.5 and 600 kg gross (Google Comlet for more info). I have no idea how one might determine whether the gear on your aircraft is supplied by Comlet, and, if so, which version you have. 



 I have no doubt that the standard 601XL gear supplied by Zenair is very strong. However, the attachments for the composite gear are very different than for the standard aluminum gear. Switching would be a lot more complex than just changing the gear. I have seen test data indicating that the heavier version of the Comlet gear passed European tests on an airplane rated at 600 kg (1320 lb) gross. It is likely that the gear on the PiperSport is the heavier version of the Comlet gear.



 If you believe that your gear is a Comlet product, I would recommend that you contact Comlet and try to determine which version of their gear you have. If you have the gear made for the European Ultralight you might look into buying the heavier version. Hopefully, the attachment brackets fit both versions.



 If you do decide to purchase the heavier gear, I would consider ordering a pair for my 601XL at the same time and we could split the trans-Atlantic shipping costs. Let me know.



 Good luck.



 Terry



 At 07:40 PM 11/28/2010 +1300, you wrote:

  	  Quote: 	
		  Hi list members

  

 We have recently had both undercarriage legs fail in quick succession.  We have an XL 601B with curved legs, which I understand are made of carbon fibre covered with fibreglass, and after a firm landing, noted on pre-flight a week later a 3 mm wide and 250 mm long longitudinal crack down the midline of the rear aspect of the left leg.  We had this replaced, then last week the other leg gave way after a further firm landing, this time transversely across the upper leg just below the attachment to the fuselage.

  

 These landings were just typical firm student landings with an instructor and leg failure was not expected from either.

  

 Has anyone had a similar experience? Any recommendations?

  

 Thanks

  

 Andrew 	
 

 

 Terry Phillips 

 ttp44~at~rkymtn.net

 Corvallis MT

 ZU-601XL/Jab 3300 s .. l .. o .. o .. w build kit - Tail & flaps are done; 

 Upgrading wings & ailerons per the AMD Safety Directive

 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.

Afterfxllc(at)aol.com
Guest

Posted: Sun Nov 28, 2010 4:56 pm Post subject: Undercarriage failures

The gear in question is Grove gear. And Zenith isn't at fault because someone elses gear failed.

 

 Jeff [quote][b]

Pete54

Joined: 27 Aug 2009
Posts: 19
Location: Scotland

Posted: Mon Nov 29, 2010 5:52 am Post subject: Re: Undercarriage failures

The composite gear supplied by CZAW comes as suggested above in a variety of weight capacities from 450kg (1050lbs) to 600kg (1320).  There are European approvals (which require not just design but also testing) at all these capacities.  Whilst the majority of European xls are notionally 450kg there are quite a number built under the experimental rules (still requiring landing gear approval unlike the US) with the heavier weights.



Mine is fitted to a 560kg xl but there  are no markings that I can see (or recall).  Having said that the factor of safety on the gear is pretty high.



Here in the UK there have been a couple of instances of composite gear cracking, not on xls ,but as you can see from the Comlet internet site they supply a lot of manufacturers of LSA type aircraft.  So there may be some quality issues, certainly at any sign of damage the gear leg is likely to be scrap.



In contrast the Zenith alloy gear (supplied by Grove?) appears to be massively strong - but the penalty is the weight - which is considerable.  Which is why someone I know who is building a US spec xl has had to get all the Us mods approved in the UK to enable him to use the 600kg mauw - largely to compensate for the weight for the weight of the gear - at 33lbs it is virtually 3 times the weight of the composite.

_________________
Pete Morris

Andrew McMenamin

Joined: 28 Nov 2010
Posts: 3
Location: Rotorua, New Zealand

Posted: Tue Nov 30, 2010 1:00 am Post subject: Re: Undercarriage failures

Thanks to all those who have replied.  I should point out that I am writing from New Zealand, so some of the S-LSA and other categories mentioned are not familiar to me.   This aircraft flies in the NZ ultralight category.

The plane was built from plans, I believe, by a LAME.  Those parts that he purchased, appear to have come from Europe. 

 

Re the XL 601b designation, I am using this as per current informal practice, to designate that the FAA and NZ CAA mandated fuselage and wing work has been completed.



Maximum AUW is listed as 544 kg. 



Thanks to those who suggested I look at the COMLET website. I have not yet re-examined the existing undercarriage for ID marks but it looks very much like the COMLET products on the COMLET website.   I will check that the weight category is compatible with the designators on the undercarriage.



At present we have found a Sport Cruiser undercarriage that we understand can be made to fit.   Does anyone have experience in such a modification?



I have been a list lurker for three or four years and this is my first posting.  Thanks again to all those who have contributed so helpfully, and any further assistance remains appreciated. 



Andrew

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