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Outrigger leg failure

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jim.naylor(at)talktalk.ne
Guest

Posted: Fri May 14, 2010 3:52 am Post subject: Outrigger leg failure

We have had a recent failure of the nylon outrigger legs on our mono. The material seems to have gone brittle and simply snapped, despite 14 years of service during which they have been subject to quite sever bending on numerous occasions when landing and taxing on rough strips without incident. They failed towards the end of a landing run on reasonably smooth grass after a smooth touchdown on a lightly loaded aircraft, so they were not subjected to any abnormal loads. There is no sign of previous cracks or damage, they have simply snapped like match sticks. 

   I recall reading about some failures in cold climates, but have not heard of any problems in warmer climes. As most people know we have had a quite severe winter in the UK as far as I can remember the coldest since our Europa has been flying. So the question is, has the properties of the material changed due to being exposed to sub zero temperatures, or has it work hardened or age hardened? On the day they failed the temperature was about 12C, so one would expect the material to have regained its flexibility.

   Any one else had problems?

   Also any alternate material suggestions?

   Jim

 

   

   [quote][b]

rampil

Joined: 04 May 2007
Posts: 870

Posted: Fri May 14, 2010 5:09 am Post subject: Re: Outrigger leg failure

Nylon slowly depolymerizes in sunight leading to embrittlement, 

and 14 years of service should have slowly accumulated a number 

of small cracks due to constant flexing loads.



Shouldn't these components be replaced at some interval?

_________________
Ira N224XS

pete(at)lawless.info
Guest

Posted: Fri May 14, 2010 5:49 am Post subject: Outrigger leg failure

Jim  

   

Do I read this right – both legs failed on the same landing?  

   

No damage done I hope?  

   

Regards  

   

pete  

   

--

kevann(at)gotsky.com
Guest

Posted: Fri May 14, 2010 6:53 am Post subject: Outrigger leg failure

Jim,

 I too have brought up this subject after several  failures. There were lots of replies of lots of failures. Some say replace the  nylon legs annually. I believe that nylon is just not the right material for  this application.

 "There is no sign of previous cracks or damage,  they have simply snapped like match sticks." I don't like that failure mode. I  have had several failures, one of which ended with taking out my Airmaster Prop.  That really hurt.

 "Also any alternate  material suggestions?" I am testing out some legs made out of  5/8"  fiberglass rod material from McMaster-Carr.

 I did some load testing in the shop to find that  this 5/8" diameter rod has almost the same flex under the same load as the 1  1/4" nylon. However, it has a very different failure mode. It of course does not  simply shatter like the nylon. The fibers in tension (on the "leading edge" of  the installed leg flexing back) start to snap and separate from the rod. It is a  more gradual failure. I think partial damage will show easily during preflight  inspection, but I have not yet seen any.

 I have attached a drawing that shows the "bushings"  that were made (from broken nylon legs) so the thinner fiberglass rod fits  in our OR-1 and wheel fork. The complete legs are about 3 ounces lighter,each.So  far they are doing well. I just installed them last month before flying to  Florida from California and back.

 Now I am making new wheel forks to run 105mm inline  skate wheels. These will have 5/8" ID tube so the lower nylon socket won't be  needed.

  

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UpperPogoNylonBushing.pdf

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fklein(at)orcasonline.com
Guest

Posted: Fri May 14, 2010 7:20 am Post subject: Outrigger leg failure

On May 14, 2010, at 7:17 AM, Kevin Klinefelter wrote:

 	  Quote: 	
		  I too have brought up this subject after several failures. There were lots of replies of lots of failures. Some say replace the nylon legs annually. I believe that nylon is just not the right material for this application. 	




Kevin,

I salute you for your analysis and thoughtful testing of an alternative to the nylon, as well as your idea to fabricate new wheel forks to match up w/ the skinny wheels...quite intriguing.

Fred



 [quote][b]

roberthatton1(at)googlema
Guest

Posted: Fri May 14, 2010 7:59 am Post subject: Outrigger leg failure

I had the starboard outrigger fail during a landing in January. This happened on a final landing after two other successful landings within the past hour of flying (none of the landings were touch and goes). I cannot remember the exact temperature but there was snow on the ground and I put the failure down to a combination of dry climate (I am based in Colorado USA) and cold temperatures making the leg brittle. Certainly the landing seemed fine and smooth and the leg just broke during the deceleration phase and not during the actual aircraft to ground contact phase of landing.   

   

After my first landing during the taxi back on the taxi-way, the outrigger that failed did get stuck briefly in a pile of snow, which I guess in hindsight would not have helped, although I completed a successful landing after this had happened. I had replaced the legs within the last two years and they were direct from the factory.  

   

The moment the outrigger departed and the wing dropped to the ground made me feel sick – the Airmaster propeller and gearbox had just been replaced on the aircraft and I was fully expecting the propeller to contact the runway. This all happened in an instant and I was concentrating on trying to keep the falling wing up with opposite aileron, steer straight and brake without nosing over so had no hands left to shut the engine down.   

   

It then became obvious that the propeller was ok and had not contacted the runway – which was a huge relief. Although I was fully expecting the underside of the wing to be a mess. Once I had stopped I had time to run the engine for a couple of minutes to correctly shut it down before hopping out to inspect the worst. Amazingly there was no damage to the wing, aileron or flaps. The stub of the outrigger that had been left after the break was worn down to the OR1, which had also been worn down at quite an angle, but this had left an inch clearance between the lowest point of the wing and the ground. I went from despair to elation in a split second! The damage was just to the outrigger and the OR1.  

   

Currently I am replacing both outrigger legs with MDS-Filled Nylon 6/6 Rod. This was a recommendation from the forum – I think Fred Klein – and I shall see how that goes. This I have sourced from McMaster-Carr and I found their ordering system and delivery excellent. This rod only seems to come in black, and is also very slightly lighter than the standard Nylon. It is meant to have greater strength than the standard nylon rod.   

   

I also ordered up the Easy-Roll Rubber tread wheel to try out, although I will be getting the inline skate wheel to try also. I have not found the “Easy-Roll” wheel to be particularly easy at rolling! The pair of wheels I have do not roll with ease at all, but I will try them first before the inline skate wheel.  

   

The only thoughts I have to this are that the OR1 saved my wing and probably propeller. I would consider replacing OR1 with a slightly longer version in order to provide more of a comfort clearance – that inch of space is very small and not far to go before greater damage.   

   

I also did think about the possibility of incorporating a spring between the OR1 and the outrigger in order to provide flexibility. Rigid enough to hold the two together but for any sharp impact allowing for flexibility.    

   

Robert Hatton  

   

       [quote][b]

grahamsingleton(at)btinte
Guest

Posted: Fri May 14, 2010 8:34 am Post subject: Outrigger leg failure

Kevin   there was a lot of testing of the outriggers, many failures. The nylon grade was chosen after a lot of experience and was the best available alternative at the time, near 20 years ago. There may well be a better alternative now but factory don't have the technical enthusiasts to find it so it's up to you guys  I'm too old too!

Graham

From: Fred Klein <fklein(at)orcasonline.com>

To:  europa-list(at)matronics.com

Sent: Friday, 14 May, 2010 16:18:31

Subject: Re: Outrigger leg failure

On May 14, 2010, at 7:17 AM, Kevin Klinefelter wrote:

 	  Quote: 	
		  I too have brought up this subject after several failures. There were lots of replies of lots of failures. Some say replace the nylon legs annually. I believe that nylon is just not the  right material for this application. 	

Kevin,

I salute you for your analysis and thoughtful testing of an alternative to the nylon, as well as your idea to fabricate new wheel forks to match up w/ the skinny wheels...quite intriguing.

Fred

 [quote]http://=======================

[b]

fklein(at)orcasonline.com
Guest

Posted: Fri May 14, 2010 9:22 am Post subject: Outrigger leg failure

On May 14, 2010, at 8:58 AM, Robert Hatton wrote:

 	  Quote: 	
		  Currently I am replacing both outrigger legs with MDS-Filled Nylon 6/6 Rod. 	




Robert,

Thanks for your report on your outrigger failure...glad to hear that there was no damage to your aircraft.

Twas not me who suggested use of MDS-filled nylon 6/6 rod...I know nothing of its properties.

Re: wheels...I'm not familiar w/ "Easy-Rolls", but the 100 or 105 mm skate (or scooter) wheels spin silently forever...be advised that when buying them you will enter the world of ABEC ratings for various bearings...I opted for #9s but you can go for the ceramics for a few more bucks...I bought my inline wheels online at www.skates.com,,,bushes are also available to enable fitting within the SS forks.

Related comment: From Kevin's drawing, he's apparently mastered the art of machining the factory-stock nylon rod...I had a devil of a time turning down my rods so that they might fit into the OR 1s. 

Fred



 [quote][b]

kevann(at)gotsky.com
Guest

Posted: Fri May 14, 2010 10:30 am Post subject: Outrigger leg failure

I had the left one fail while taxi turning right at  an average fast walking speed. When the leg breaks, the wigtip just clears the  ground. But the noise you may hear from the OR-1 grinding on the pavement made  me want to stop right now! The glider pilot in me probably took over and I think  I applied the brake. That's the wrong thing to do, especially in a turn away  from the low wing. It will nose over MUCH easier in that configuration. That was  it for the prop, and the wingtip lost some paint.

  

 I had another one break on a bouncy landing with my  insructor in the right seat.No brake applied and some loss of directional  control. Damage was limited to the OR-1.

  

 I broke another on a bounced go-around. I thought I  heard it break, but of course you can't see it from the cockpit. I made a low  pass and saw it littering the runway.That inspired me to do a good landing  (finally) and hold the wing up with aileron to a full stop with brake after  slowing and turning slightly toward the broken side.

  

 I broke one in the hanger. I was pushing down on  the wing tip to see the flex of my newly replaced outrigger and it  shattered.

  

 All these failures happened in above freezing  temps, but I did not record actual temps. I bought replacement Nylon 6/6 from  McMaster.

  

 Look at the data sheets before deciding on the  MDS-filled Nylon (available on McMaster site). As I recall, it is no better for  this application. 

  

 I'll let ya'll know if I ever break one of my  fiberglass legs.

  

 Kevin

 N211KA

  

  

   [quote][b]

kevann(at)gotsky.com
Guest

Posted: Fri May 14, 2010 10:48 am Post subject: Outrigger leg failure

[quote]    

   Twas not me who suggested use of MDS-filled nylon 6/6 rod...I know    nothing of its properties.

    

   I think it was Erich Trombley that said he was    using the above...

   



   Re: wheels...I'm not familiar w/ "Easy-Rolls", but the 100 or 105 mm    skate (or scooter) wheels spin silently forever...be advised that when buying    them you will enter the world of ABEC ratings for various bearings...I opted    for #9s but you can go for the ceramics for a few more bucks...I bought my    inline wheels online at www.skates.com,,,bushes are also available to    enable fitting within the SS forks.

    

   Thanks for that link, they have good service and    reasonable prices.

   



   Related comment: From Kevin's drawing, he's apparently mastered    the art of machining the factory-stock nylon rod...I had a devil of a time    turning down my rods so that they might fit into the OR 1s. 

    

   I am fortunate to have a friend close by with a    lathe and a milling machine in his garage. He made the drawing and turned the    rod into the part drawn. I plan to get with him on drawing up new slim    forks for the skate wheels to go with the 5/8" fiberglass legs.

   



   Kevin

   N211KA

   



   

 	  Quote: 	
		  



href="http://www.matronics.com/Navigator?Europa-List">http://www.matronhref="http://forums.matronics.com">http://forums.matronics.com

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

	
[b]

roberthatton1(at)googlema
Guest

Posted: Fri May 14, 2010 11:47 am Post subject: Outrigger leg failure

Sorry Fred, I must have got mixed up for I was looking at wheels at the same time as outrigger material etc. Apologies if I caused any confusion.  

   

Robert  

   

       

From: owner-europa-list-server(at)matronics.com [mailto:owner-europa-list-server(at)matronics.com] On Behalf Of Fred Klein

 Sent: Friday, May 14, 2010 6:20 PM

 To: europa-list(at)matronics.com

 Subject: Re: Outrigger leg failure  

  

  

   

       

On May 14, 2010, at 8:58 AM, Robert Hatton wrote:  

  



 

   

Currently I am replacing both outrigger legs with MDS-Filled Nylon 6/6 Rod.  

   

    

Robert,  

    

   

    

Thanks for your report on your outrigger failure...glad to hear that there was no damage to your aircraft.  

    

   

    

Twas not me who suggested use of MDS-filled nylon 6/6 rod...I know nothing of its properties.  

    

   

    

Re: wheels...I'm not familiar w/ "Easy-Rolls", but the 100 or 105 mm skate (or scooter) wheels spin silently forever...be advised that when buying them you will enter the world of ABEC ratings for various bearings...I opted for #9s but you can go for the ceramics for a few more bucks...I bought my inline wheels online at www.skates.com,,,bushes are also available to enable fitting within the SS forks.  

    

   

    

Related comment: From Kevin's drawing, he's apparently mastered the art of machining the factory-stock nylon rod...I had a devil of a time turning down my rods so that they might fit into the OR 1s.   

    

   

    

Fred  

    

   

    

   

  

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rampil

Joined: 04 May 2007
Posts: 870

Posted: Fri May 14, 2010 11:55 am Post subject: Re: Outrigger leg failure

I don't believe nylon polymer is the wrong material for the application.

When new it is probably a lot better in flex than some sort of FRP.

Fourteen years just seems a really long time to have any sort of

plastic exposed to UV.  Inspection of condition should include

a hand lens for checking and small cracks.  There is a UV-resistant

nylon which is unfortunately black in color.  Even lexan polycarbonate

windshields will deteriorate after 14 years in sunlight.



FRP will need to painted with UV-resistant primer for protection from 

the sun also.

_________________
Ira N224XS

erichdtrombley(at)juno.co
Guest

Posted: Sun May 16, 2010 1:50 pm Post subject: Outrigger leg failure

Yes, it was me who suggested the use of MDS-filled nylon material from McMaster-Carr.  I did some research during the selection process and if I remember correctly the MDS-filled nylon had the same or better flexural strength, better UV protection and slightly better impact strength.  I have had my legs in service for just over seven years without issue.  I too am using inline scooter wheels with a slimmed down mounting fork.  I will take a picture and post it.



Erich Trombley

N28ET Classic Mono 914



Time: 11:48:18 AM PST US

From: "Kevin Klinefelter" <kevann(at)gotsky.com>

Subject: Re: Outrigger leg failure

  Twas not me who suggested use of MDS-filled nylon 6/6 rod...I know 

nothing of its properties.



  I think it was Erich Trombley that said he was using the above...

  Re: wheels...I'm not familiar w/ "Easy-Rolls", but the 100 or 105 mm 

skate (or scooter) wheels spin silently forever...be advised that when 

buying them you will enter the world of ABEC ratings for various 

bearings...I opted for #9s but you can go for the ceramics for a few 

more bucks...I bought my inline wheels online at www.skates.com,,,bushes 

are also available to enable fitting within the SS forks.



  Thanks for that link, they have good service and reasonable prices.

  Related comment: From Kevin's drawing, he's apparently mastered the 

art of machining the factory-stock nylon rod...I had a devil of a time 

turning down my rods so that they might fit into the OR 1s. 



  I am fortunate to have a friend close by with a lathe and a milling 

machine in his garage. He made the drawing and turned the rod into the 

part drawn. I plan to get with him on drawing up new slim forks for the 

skate wheels to go with the 5/8" fiberglass legs.

  Kevin

  N211KA



____________________________________________________________

Penny Stock Jumping 2000%

Sign up to the #1 voted penny stock newsletter for free today!

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fklein(at)orcasonline.com
Guest

Posted: Sun May 16, 2010 3:37 pm Post subject: Outrigger leg failure

On May 16, 2010, at 2:47 PM, Erich Trombley wrote:



 	  Quote: 	
		   I too am using inline scooter wheels with a slimmed down mounting  

 fork.  I will take a picture and post it.


	


Erich...please consider posting some pixs and description of your  

retraction mechanism as well...I was quite intrigued by your  

description at SnF last year...Fred

kevann(at)gotsky.com
Guest

Posted: Sun May 16, 2010 6:02 pm Post subject: Outrigger leg failure

Hi Erich,



What materials did you use to make your scooter wheel forks? I just got some 

.080 4130 steel sheet for a first try on the forks and .058 wall 3/4" (which 

is 5/8"ID) 4130 tube for the outrigger leg socket.

Looking forward to seeing a picture, too.

And I'm glad to hear that the MDS-filled nylon legs are serving you well. I 

thought I remembered that the MDS-filled nylon had lower friction 

properties, but was not any stronger. I'll see if I can find that info 

again.

Did you ever break a Nylon 6/6 leg?



Kevin

N211KA XS Mono 914

---

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