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don(at)hudgeon.com
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 Posted: Sun Jun 21, 2009 1:44 pm Post subject: Fwd: Avid Gear |
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I am I new poster and have a few questions in reference to the discussion on landing gear and bungees. I am seriously considering purchasing an Avid MK 4 with about 160 hours total time. It has Stratus EA81 and lengthened fuselage. The truss assembly shown in the pics has been bent and obviously been repaired quite poorly. I have checked with Airdale and they now have a updated version available from heavier wall 5/8 tubing. Airdale advises they have supplied about 3 or 4 of these just this spring!
Anyway someone here has stated that this is a most difficult structural repair to make. Have any of you ever done this and what should I be on the lookout for. Also can anyone give me an opinion as to what else I should be suspecting or is this a fairly common failure to this truss.
You comments are WELCOME!!! Hope the pic is OK
Cheers Don
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Tom Jones
Joined: 12 Mar 2006
Posts: 752
Location: Ellensburg, WA
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| Posted: Sun Jun 21, 2009 2:35 pm Post subject: Re: Fwd: Avid Gear |
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| Quote: | | Have any of you ever done this and what should I be on the lookout for. |
I haven't replaced a bungee truss myself but I have talked with the old Skystar factory welder that has replaced them in a kitfox.
The welder said it is not a difficult job for someone that knows how to do it.
The thing to watch out for is the fuselage can " flex out of alignment" when the old truss is cut out and must be "Tweaked" back when welding the new one in. By the looks of that one the fuselage may already be tweaked.
I would ask Airdale if they have the specifications and method to measure/check the fuselage.
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Tom Jones
Classic IV
503 Rotax, 72 inch Two blade Warp
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dholly
Joined: 19 Dec 2006
Posts: 40
Location: Upstate NY
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| Posted: Mon Jun 22, 2009 5:21 am Post subject: Re: Fwd: Avid Gear |
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Don,
There was a recent discussion on the Avid Flyer Yahoo Group forum about repairing bent seat trusses. One poster added a link to several photos about his repair where several tubes were cut out and replaced. I suppose it is a job someone with the appropriate tools and skill could tackle, but nothing I would attempt. It certainly looks as if the truss in your pic would benefit from a complete replacement, maybe even some of the side longerons too. As mentioned, I would find a way to ensure the fuse was aligned properly before doing so. If you are anywhere near Airdale, perhaps they can jig the fuse and do the repair for you. As of Jan '09, Airdale Flyer, LLC has a new name, address and owner. New contact info is:
Airdale Sportplane and Supply
W175 Hildebrand Lake Road
Rhinelander, WI 54501
email: sales(at)airdale.com
website: www.airdale.com
tel: (715) 369-1343
owner: Brett McKinney
As an aside, it seems many of these bent seat truss incidents could have easily been avoided if the bungee installation was done correctly with the proper number of wraps and correct MIL Spec cord (your pic looks correct). Here's a helpful post I saved:
| Quote: | The LATEST bungees that AVID Made --post 1993 were different than earlier types. Mainly because the empty weight and gross weight INCREASED. We in the Uk, found that the earlier bungees, a kind of SILVERY Outer with Black flecks in them, were commercial Bungee cord as found in sports stores etc. and very very weak / inconsistent in "stretchiness" The book /manual just stated something like put as many wraps on as you could get...not good---some people managed 6 others 8 and some even 9--the more wraps the LESS stretch till finally no stretch and then solid gear- heavy landing no stretch so they bent and broke the seat truss, propeller, wing tip flaperon etc $$$$ We found that the OLD cord was too lightweight to comply with landing gear loads and we found that a Mil Spec cord met all the requirement necessary---- Kitfoxes went the same way!! After 1993 Avid used Mil spec cord TOTALLY-- we have done so ALL the time. This cord is a Beigeish Outer Cottony braid with colored flecks in it-- the color could be just one color or maybe two--this is a date code of manufacture so varies from batch to batch. On all Avids, with these cords, the wraps are 7 and Seven only--you cannot physically get more than 7--it just won't stretch that far. (It is 8 full wraps on OUR WIDE Gear) The way to wrap the bungee is to measure the overall length first. Loop to loop... should be around 90". Divide this number by 7 (approx 13") (= number of wraps). Start at one end of bungee and use a pencil/marker and measure/mark 6.5" 'ish. Then mark again at 19.5", 32.5", 45.5" and so on till end. Last mark will be abouit 6.5" 'ish from loop. To install use two people... or Adult + Child... Put child inside cockpit and have them feed the cord thru the gap. 2nd person underneath.. Hook cord on peg in cockpit and feed down thru gap. Pull to first mark on bottom of gearleg..easy---- about 3/8" stretch put thumb on mark on gear leg--feed back up thru gap and get helper to loop around seat truss and feed end back. Pull end thru and get second mark on gear leg--- Thumb on 2nd mark and then feed back up again. Continues until you have all marks in line on bottom of gear leg and hook the final leg back onto other side of peg-- This is easiest way to do it, does not need some WWF guy to stretch and hold in place AND gives EVEN tension in the cord... Works every time... Should be similar with Kfoxes --but cord lengths different and maybe #of wraps...
Best regards,
Steve at Airdale.. |
Also, rather than welding on reinforcing steel to your perfectly good seat truss and risk heat softening the tubes, it is recommended that 1/4" ply gussets be epoxied into the truss bridgework (see pic). Theory being, it will help keep the top tube from being deformed in a hard landing, but give if sufficiently hard and prevent transferring bending force to other framework.
Hope that helps, good luck.
-Doug
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| Seat/bungee truss strengthener tip |
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-Kitfox III 582 Blue/C Grove Spring / Aerocet 1100 Amphibs
-Airdale Avid+ (project) TD / W.I.B. Gear |
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thesupe(at)hotmail.com
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| Posted: Mon Jun 22, 2009 5:48 am Post subject: Fwd: Avid Gear |
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This is not a completly uncommon thing to happen on an Avid in a hard landing C the seat truss is a bit of a weak point. Avid recommended filling the spaces between the truss tubing with 1/4" plywood as a way to strengthen the truss. I've had some experience with buckling a truss myself on my MK IV Avid. It had been repaired before I got it and I think it ended up weaker than it should have been C because it bent on me and I didn't think I hit all that hard. I'm not trying to chase you off this list or anything C but if you look in the Yahoo groups Avid list archives C there is a lot of info about seat trusses. I know there is info on the width you should have between the tubing at the ends of the truss C because I asked that question and it was answered by Steve Winder and others. (Steve ran the Avid factory for years) Looking at yours C I would probably suggest cutting out the old truss and replacing it with a new one. You could also just get the tubing and cut and fit all the new pieces back in. When I repaired mine C I cut the fabric back to the back of the doors and then replaced that much after the repair. If you want to talk about it C send me your # and I can call you. Take care C Jim Chuk
Date: Sun C 21 Jun 2009 14:40:34 -0700
Subject: Fwd: Avid Gear
From: don(at)hudgeon.com
To: kitfox-list(at)matronics.com
I am I new poster and have a few questions in reference to the discussion on landing gear and bungees. I am seriously considering purchasing an Avid MK 4 with about 160 hours total time. It has Stratus EA81 and lengthened fuselage. The truss assembly shown in the pics has been bent and obviously been repaired quite poorly. I have checked with Airdale and they now have a updated version available from heavier wall 5/8 tubing. Airdale advises they have supplied about 3 or 4 of these just this spring!
Anyway someone here has stated that this is a most difficult structural repair to make. Have any of you ever done this and what should I be on the lookout for. Also can anyone give me an opinion as to what else I should be suspecting or is this a fairly common failure to this truss.
You comments are WELCOME!!! Hope the pic is OK
Cheers Don
Hotmail® has ever-growing storage! Don’t worry about storage limits. Check it out. [quote][b]
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don(at)hudgeon.com
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| Posted: Mon Jun 22, 2009 7:19 pm Post subject: Fwd: Avid Gear |
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Hi Jim
Thanks for the valuable information. I will look on the Yahoo site. Was yours bent about the same as this? Did you have any distortion on the longerons? If I do buy this I will probably have Airdale make me up a new updated truss.
Cheers
Don
On Mon, Jun 22, 2009 at 6:45 AM, Jim_and_Lucy Chuk <thesupe(at)hotmail.com (thesupe(at)hotmail.com)> wrote:
[quote] This is not a completly uncommon thing to happen on an Avid in a hard landing, the seat truss is a bit of a weak point. Avid recommended filling the spaces between the truss tubing with 1/4" plywood as a way to strengthen the truss. I've had some experience with buckling a truss myself on my MK IV Avid. It had been repaired before I got it and I think it ended up weaker than it should have been, because it bent on me and I didn't think I hit all that hard. I'm not trying to chase you off this list or anything, but if you look in the Yahoo groups Avid list archives, there is a lot of info about seat trusses. I know there is info on the width you should have between the tubing at the ends of the truss, because I asked that question and it was answered by Steve Winder and others. (Steve ran the Avid factory for years) Looking at yours, I would probably suggest cutting out the old truss and replacing it with a new one. You could also just get the tubing and cut and fit all the new pieces back in. When I repaired mine, I cut the fabric back to the back of the doors and then replaced that much after the repair. If you want to talk about it, send me your # and I can call you. Take care, Jim Chuk
Date: Sun, 21 Jun 2009 14:40:34 -0700
Subject: Fwd: Avid Gear
From: don(at)hudgeon.com (don(at)hudgeon.com)
To: kitfox-list(at)matronics.com (kitfox-list(at)matronics.com)
I am I new poster and have a few questions in reference to the discussion on landing gear and bungees. I am seriously considering purchasing an Avid MK 4 with about 160 hours total time. It has Stratus EA81 and lengthened fuselage. The truss assembly shown in the pics has been bent and obviously been repaired quite poorly. I have checked with Airdale and they now have a updated version available from heavier wall 5/8 tubing. Airdale advises they have supplied about 3 or 4 of these just this spring!
Anyway someone here has stated that this is a most difficult structural repair to make. Have any of you ever done this and what should I be on the lookout for. Also can anyone give me an opinion as to what else I should be suspecting or is this a fairly common failure to this truss.
You comments are WELCOME!!! Hope the pic is OK
Cheers Don
Hotmail® has ever-growing storage! Don’t worry about storage limits. Check it out. | Quote: |
arget="_blank">http://www.matronics.com/Navigator?Kitfox-List
tp://forums.matronics.com
_blank">http://www.matronics.com/contribution
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don(at)hudgeon.com
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| Posted: Mon Jun 22, 2009 7:22 pm Post subject: Fwd: Avid Gear |
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G`day Doug
Thanks again for this info. I can`t believe how responsive and helpful folks on this site are. Will keep you posted.
Cheers
Don
On Mon, Jun 22, 2009 at 6:21 AM, dholly <oue191(at)yahoo.com (oue191(at)yahoo.com)> wrote:
[quote]--> Kitfox-List message posted by: "dholly" <oue191(at)yahoo.com (oue191(at)yahoo.com)>
Don,
There was a recent discussion on the Avid Flyer Yahoo Group forum about repairing bent seat trusses. One poster added a link to several photos about his repair where several tubes were cut out and replaced. I suppose it is a job someone with the appropriate tools and skill could tackle, but nothing I would attempt. It certainly looks as if the truss in your pic would benefit from a complete replacement, maybe even some of the side longerons too. As mentioned, I would find a way to ensure the fuse was aligned properly before doing so. If you are anywhere near Airdale, perhaps they can jig the fuse and do the repair for you. As of Jan '09, Airdale Flyer, LLC has a new name, address and owner. New contact info is:
Airdale Sportplane and Supply
W175 Hildebrand Lake Road
Rhinelander, WI 54501
email: sales(at)airdale.com (sales(at)airdale.com)
website: www.airdale.com
tel: (715) 369-1343
owner: Brett McKinney
As an aside, it seems many of these bent seat truss incidents could have easily been avoided if the bungee installation was done correctly with the proper number of wraps and correct MIL Spec cord (your pic looks correct). Here's a helpful post I saved:
> The LATEST bungees that AVID Made --post 1993 were different than earlier types. Mainly because the empty weight and gross weight INCREASED. We in the Uk, found that the earlier bungees, a kind of SILVERY Outer with Black flecks in them, were commercial Bungee cord as found in sports stores etc. and very very weak / inconsistent in "stretchiness" The book /manual just stated something like put as many wraps on as you could get...not good---some people managed 6 others 8 and some even 9--the more wraps the LESS stretch till finally no stretch and then solid gear- heavy landing no stretch so they bent and broke the seat truss, propeller, wing tip flaperon etc $$$$ We found that the OLD cord was too lightweight to comply with landing gear loads and we found that a Mil Spec cord met all the requirement necessary---- Kitfoxes went the same way!! After 1993 Avid used Mil spec cord TOTALLY-- we have done so ALL the time. This cord is a Beigeish Outer Cottony braid with colored fl!
ecks in it-- the color could be just one color or maybe two--this is a date code of manufacture so varies from batch to batch. On all Avids, with these cords, the wraps are 7 and Seven only--you cannot physically get more than 7--it just won't stretch that far. (It is 8 full wraps on OUR WIDE Gear) The way to wrap the bungee is to measure the overall length first. Loop to loop... should be around 90". Divide this number by 7 (approx 13") (= number of wraps). Start at one end of bungee and use a pencil/marker and measure/mark 6.5" 'ish. Then mark again at 19.5", 32.5", 45.5" and so on till end. Last mark will be abouit 6.5" 'ish from loop. To install use two people... or Adult + Child... Put child inside cockpit and have them feed the cord thru the gap. 2nd person underneath.. Hook cord on peg in cockpit and feed down thru gap. Pull to first mark on bottom of gearleg..easy---- about 3/8" stretch put thumb on mark on gear leg--feed back up thru gap and get helper to loop arou!
nd seat truss and feed end back. Pull end thru and get second !
mark on
gear leg--- Thumb on 2nd mark and then feed back up again. Continues until you have all marks in line on bottom of gear leg and hook the final leg back onto other side of peg-- This is easiest way to do it, does not need some WWF guy to stretch and hold in place AND gives EVEN tension in the cord... Works every time... Should be similar with Kfoxes --but cord lengths different and maybe #of wraps...
> Best regards,
> Steve at Airdale..
Also, rather than welding on reinforcing steel to your perfectly good seat truss and risk heat softening the tubes, it is recommended that 1/4" ply gussets be epoxied into the truss bridgework (see pic). Theory being, it will help keep the top tube from being deformed in a hard landing, but give if sufficiently hard and prevent transferring bending force to other framework.
Hope that helps, good luck.
-Doug
--------
Airdale Avid+ project | Aerocet 1100 Amphibs
Read this topic online here:
http://forums.matronics.com/viewtopic.php?p=249502#249502
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akflyer
Joined: 07 May 2007
Posts: 574
Location: Soldotna AK
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| Posted: Tue Jun 23, 2009 8:11 am Post subject: Re: Fwd: Avid Gear |
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My seat truss and longerons were bent pretty good. As long as the tubes are not buckled, you would be surprised what you can do with a block of wood and a soft blow hammer. I used .020" 4130 plate on the sides of the fuse from the firewall back to the strut attach point to add some rigidity to the fuse sides to keep them from bending again. Seems to do the trick as I have beat it pretty good on skis hitting ice chunks and snowmachine tracks.
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_________________
DO NOT ARCHIVE
Leonard Perry aka SNAKE
Soldotna AK
Avid "C" / Mk IV
582 (147 hrs and counting on the rebuild)
IVO IFA
Full Lotus 1450
#1 snake oil salesman since 1-22-2009
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