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FireFly Wing Swivel Joint Repair
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jbhart(at)onlyinternet.ne
Guest

Posted: Mon Jun 19, 2006 7:19 am Post subject: FireFly Wing Swivel Joint Repair

FireFlyer's,



After 200+ hours the FireFly rear wing spar swivel joints started to sound 

like tinny sleigh bells.  Earlier I had shimmed them with thin brass shim 

stock.  Some of the shims stayed in place and others did not.  As a result, 

all the shaking and quaking at the rear of the fuselage slowly wore the pin 

OD's and the mating hole ID's.  



I purchased some inexpensive Oilite flanged sleeve bushings from McMaster 

Carr, drilled out the holes, inserted the bearings, and new slightly longer 

pins and removed all the play from the swivel joints.  Also, I bushed the 

stud that passes through the cage clevis.  I used a washer and two nested 

"O" rings so that I could put the joint into compression but still let it 

pivot.



Before the repair, the trailing edge of the wing would move over an eight of 

an inch.  After the repair, there is no movement.  The nice thing about this 

repair is that if play shows up again, all one has to do is replace the 

bushings.  There should be little to no wear on the steel surfaces. 



If you would like to see how it was done, it can be seen at:



http://www.thirdshift.com/jack/firefly/firefly128.html



Jack B. Hart FF004

Winchester, IN

jeepacro(at)cox.net
Guest

Posted: Mon Jun 19, 2006 8:04 am Post subject: FireFly Wing Swivel Joint Repair

I can't seem to open up the pictures of the repair of swivel joint.  Can you send me some pictures?  Thanks in advance

--

Rob.



---- "Jack B. Hart" <jbhart(at)onlyinternet.net> wrote: 

 	  Quote: 	
		   

 

 FireFlyer's,

 

 After 200+ hours the FireFly rear wing spar swivel joints started to sound 

 like tinny sleigh bells.  Earlier I had shimmed them with thin brass shim 

 stock.  Some of the shims stayed in place and others did not.  As a result, 

 all the shaking and quaking at the rear of the fuselage slowly wore the pin 

 OD's and the mating hole ID's.  

 

 I purchased some inexpensive Oilite flanged sleeve bushings from McMaster 

 Carr, drilled out the holes, inserted the bearings, and new slightly longer 

 pins and removed all the play from the swivel joints.  Also, I bushed the 

 stud that passes through the cage clevis.  I used a washer and two nested 

 "O" rings so that I could put the joint into compression but still let it 

 pivot.

 

 Before the repair, the trailing edge of the wing would move over an eight of 

 an inch.  After the repair, there is no movement.  The nice thing about this 

 repair is that if play shows up again, all one has to do is replace the 

 bushings.  There should be little to no wear on the steel surfaces. 

 

 If you would like to see how it was done, it can be seen at:

 

 http://www.thirdshift.com/jack/firefly/firefly128.html

 

 Jack B. Hart FF004

 Winchester, IN

John Hauck

Joined: 09 Jan 2006
Posts: 4639
Location: Titus, Alabama (hauck's holler)

Posted: Mon Jun 19, 2006 10:04 am Post subject: FireFly Wing Swivel Joint Repair

| After 200+ hours the FireFly rear wing spar swivel joints started 

to sound

| like tinny sleigh bells.  Earlier I had shimmed them with thin brass 

shim

| stock.  Some of the shims stayed in place and others did not.  As a 

result,

| all the shaking and quaking at the rear of the fuselage slowly wore 

the pin

| OD's and the mating hole ID's.

|

| I purchased some inexpensive Oilite flanged sleeve bushings from 

McMaster

| Carr, drilled out the holes, inserted the bearings, and new slightly 

longer

| pins and removed all the play from the swivel joints.  Also, I 

bushed the

| stud that passes through the cage clevis.  I used a washer and two 

nested

| "O" rings so that I could put the joint into compression but still 

let it

| pivot.

|

| Before the repair, the trailing edge of the wing would move over an 

eight of

| an inch.  After the repair, there is no movement.  The nice thing 

about this

| repair is that if play shows up again, all one has to do is replace 

the

| bushings.  There should be little to no wear on the steel surfaces.

|

| If you would like to see how it was done, it can be seen at:

|

| http://www.thirdshift.com/jack/firefly/firefly128.html

|

| Jack B. Hart FF004

| Winchester, IN

|

|

|

|

|

|

|

|

|

|

|

|

|

|

_________________
John Hauck
MKIII/912ULS
hauck's holler
Titus, Alabama

planecrazzzy
Guest

Posted: Mon Jun 19, 2006 12:55 pm Post subject: Re: FireFly Wing Swivel Joint Repair

Hi Jack,

           Nice work and nice illustrations...



 Question....Aren't you supposed to have Bolts on those ears instead of

 Pins....?



                       Gotta Fly...

                                       Mike in MN

jbhart(at)onlyinternet.ne
Guest

Posted: Mon Jun 19, 2006 1:17 pm Post subject: FireFly Wing Swivel Joint Repair

At 01:55 PM 6/19/06 -0700, you wrote:

 	  Quote: 	
		  



Hi Jack,

           Nice work and nice illustrations...



 Question....Aren't you supposed to have Bolts on those ears instead of

 Pins....?



                       Gotta Fly...

                                       Mike in MN


	


Mike,



The loads are pure shear loads so there is no need for bolts.  Pins for 

a given holding distance are lighter than bolts.



Jack B. Hart FF004

Winchester, IN

Gene Ledbetter

Joined: 10 Jan 2006
Posts: 20
Location: Cincinnati, OH

Posted: Tue Jun 20, 2006 6:34 pm Post subject: Re: FireFly Wing Swivel Joint Repair

Jack, 

I checked my Firefly Wing Swivel Joints today and after 328 hours can report that there is minimum wing movement.  I have always used bolts for the swivel joint connections and although that may not be significant, it has allowed the joints to be tightened to the point that the bolts have never been loose to move or shake.

Gene

_________________
Gene D.
2000 Firefly
330 Hours
New 447
Brakes, Ivo

John Hauck

Joined: 09 Jan 2006
Posts: 4639
Location: Titus, Alabama (hauck's holler)

Posted: Tue Jun 20, 2006 7:47 pm Post subject: FireFly Wing Swivel Joint Repair

mating hole ID's.

|

| I purchased some inexpensive Oilite flanged sleeve bushings from 

McMaster

| Carr, drilled out the holes, inserted the bearings, and new slightly 

longer

| pins and removed all the play from the swivel joints.  Also, I 

bushed the

| stud that passes through the cage clevis.  I used a washer and two 

nested

| "O" rings so that I could put the joint into compression but still 

let it

| pivot.

 |

| Jack B. Hart FF004



Jack:



Looks like you have drastically deviated from Kolb plans and 

instructions on how to attach the wing fold universal joint and 

attachment to the cage.



After more than 2,500 hours flight time, I have not had a requirement 

to change out the bolts in the wing fold universal joint, nor adjust 

the tension on the attachment hardware to the cage.  These parts of my 

mkIII remain snug, safe, and secure.



Don't believe bronze bushings are the remedy to your problem.  Quite 

possibly, had you used bolts washer and nyloc nuts as prescribed by 

the plans and instructions, you would not have wear on your "clevis 

pins" and holes in the universal joints.



Reference the attachment at the cage, two "O" rings are not going to 

keep that piece of hardware from moving on the ground and in flight, 

when the wings are loading and unloading.  A combination of thick and 

thin AN washers will give you the appropriate snugness required at 

this point with castellated nut and cotter pin.



If the bolts are snugged up tight after the wings are repositioned 

from storage to flight position, wear on these bolts and holes will 

certainly be discouraged.  If I had to fold my airplane after each 

flying session, I would insure the bolts in the universal joints were 

loose during the flight prep process, snugging them up tight prior to 

flight.  When time came to fold the airplane, a second or two to 

loosen these bolts prior to folding the wings.



NOTE:  Jack can configure his FF any way he wants to, as anyone else 

can do likewise.  However, let it be noted that his procedure for 

taking slack out of the wing fold universal joint and wing attachment 

to the fuselage is certainly not a "normal, safe, recommended" method 

of maintenance.



"Nuther NOTE:  This is in no way a personal attack on Jack Hart.



john h

mkIII

_________________
John Hauck
MKIII/912ULS
hauck's holler
Titus, Alabama

Eugene Zimmerman

Joined: 10 Jan 2006
Posts: 392

Posted: Tue Jun 20, 2006 8:24 pm Post subject: FireFly Wing Swivel Joint Repair

Huh ? What? Is the list funky, or are you shooting blanks?

On Jun 19, 2006, at 2:03 PM, John Hauck wrote:



 	  Quote: 	
		   



  | After 200+ hours the FireFly rear wing spar swivel joints started

 to sound

 | like tinny sleigh bells.  Earlier I had shimmed them with thin brass

 shim

 | stock.  Some of the shims stayed in place and others did not.  As a

 result,

 | all the shaking and quaking at the rear of the fuselage slowly wore

 the pin

 | OD's and the mating hole ID's.

 |

 | I purchased some inexpensive Oilite flanged sleeve bushings from

 McMaster

 | Carr, drilled out the holes, inserted the bearings, and new slightly

 longer

 | pins and removed all the play from the swivel joints.  Also, I

 bushed the

 | stud that passes through the cage clevis.  I used a washer and two

 nested

 | "O" rings so that I could put the joint into compression but still

 let it

 | pivot.

 |

 | Before the repair, the trailing edge of the wing would move over an

 eight of

 | an inch.  After the repair, there is no movement.  The nice thing

 about this

 | repair is that if play shows up again, all one has to do is replace

 the

 | bushings.  There should be little to no wear on the steel surfaces.

 |

 | If you would like to see how it was done, it can be seen at:

 |

 | http://www.thirdshift.com/jack/firefly/firefly128.html

 |

 | Jack B. Hart FF004

 | Winchester, IN

 |

 |

 |

 |

 |

 |

 |

 |

 |

 |

 |

 |

 |

 |

John Hauck

Joined: 09 Jan 2006
Posts: 4639
Location: Titus, Alabama (hauck's holler)

Posted: Tue Jun 20, 2006 8:39 pm Post subject: FireFly Wing Swivel Joint Repair

Eugene Zimmerman <etzim62(at)earthlink.net>

|

| Huh ? What? Is the list funky, or are you shooting blanks?

Shoot'n blanks.............



john h



PS:  A msg I posted yesterday afternoon came strolling across my 

monitor late tonight.  Always better the second time around.  Maybe it 

was a shadow.

_________________
John Hauck
MKIII/912ULS
hauck's holler
Titus, Alabama

R. Hankins

Joined: 18 Jan 2006
Posts: 185
Location: Grants Pass, Oregon

Posted: Tue Jun 20, 2006 9:16 pm Post subject: Re: FireFly Wing Swivel Joint Repair

Jack:



You are scaring me, Jack.  In theory the pins are in pure shear loading.  The shear load is not what will bite you.  If the ears of the piece closest to the cage try to spread the clip on the pin will be sheared off and we may be reading unwelcome stories of your early demise.  Another failure mode:   the vibration that forced the repair in the first place may weaken the clip or safety ring as it rattles in the pin hole.  Safety pins and rings are made in China more often then not these days, even when purchased from a reputable source.  In my mind, a weight savings of less than an ounce doesn't justify the added risk. 



The bushings look nice, but those pins scare the puddin' out of me.  Those are "Oh Sh-t" bolts you are playing with.

_________________
Roger in Oregon
1992 KXP 503 - N1782C

Eugene Zimmerman

Joined: 10 Jan 2006
Posts: 392

Posted: Wed Jun 21, 2006 3:46 am Post subject: FireFly Wing Swivel Joint Repair

John / Kolb Folks,



I also believe that Jack Hart's swivel joint repair is not one of his  

characteristically good  ideas.

In my humble opinion removing metal to install bushings and o-rings  

in the swivel joint  is NOT a GOOD idea or actual improvement.

Finding and correcting the cause and replacing the worn parts would  

much better.

Worn swivel joints is not a common problem on Kolb planes.

Could it be possible that some of Jack's other modifications  

contributed to the unusual wear of these parts?

His engine/redrive may well have a different vibration profile than  

the standard 447 Rotax.

On Jun 21, 2006, at 12:40 AM, John Hauck wrote:



 	  Quote: 	
		   



  Eugene Zimmerman <etzim62(at)earthlink.net>

 |

 | Huh ? What? Is the list funky, or are you shooting blanks?

 Shoot'n blanks.............



 john h



 PS:  A msg I posted yesterday afternoon came strolling across my

 monitor late tonight.  Always better the second time around.  Maybe it

 was a shadow.

jbhart(at)onlyinternet.ne
Guest

Posted: Wed Jun 21, 2006 5:47 am Post subject: FireFly Wing Swivel Joint Repair

At 07:43 AM 6/21/06 -0400, you wrote:

 	  Quote: 	
		  


	


Eugene and Kolbers,



First of all, I apologize to all who I have offended, BUT what is wrong with 

providing a bearing material in a rotating joint?  Since a rotating joint of 

similar material is always going to show greater wear than if one surface is 

made of a bearing material, why not change it?  For less than four dollars, 

I have the equivalent of a new and improved swivel joint.



As for strength, I sent the following to another Kolber:



"I know it looks bad but we are fortunate that Homer and/or Dennis gave us a 

very robust design in this area.  The steel is 0.125 inches thick.  

.......................................  To check out the worst case, the 

tangs for the clevis that attaches to the wing attachment point is only 

0.875 inches wide.  By drilling the 5/16 inch ID out to 7/16 of an inch you 

have a cross sectional area to support tension or compression of 7/16 times 

1/8. Or the equivalent of 0.055 square inches.  Unhardened 4130 has a yield 

stress of 95,000 psi, so each tang will support (95,000 x -.055) 5,195 

pounds or the modified clevis will support over five tons before yielding."



Jack B. Hart FF004

Winchester, IN

Thom Riddle

Joined: 10 Jan 2006
Posts: 1597
Location: Buffalo, NY, USA (9G0)

Posted: Wed Jun 21, 2006 8:28 am Post subject: FireFly Wing Swivel Joint Repair

Jack,



As a fellow retired mechanical engineer and machine designer, I don't 

see a thing wrong with your use of hi-strength close tolerance pins and 

oilite bushings. I can't count the number of times I've used oilite 

bushings and hi-strength pins in machine designs subject to extreme 

vibration and impact loads in shear with no failures ever. Not sure I 

would have put o-rings there because they will compress, as you stated, 

but since the longitudinal loads on these pins are minimal, probably 

not much of an issue.



Thom in Buffalo

_________________
Thom Riddle
Buffalo, NY (9G0)

Don't worry about old age... it doesn't last very long.
- Anonymous

Eugene Zimmerman

Joined: 10 Jan 2006
Posts: 392

Posted: Wed Jun 21, 2006 8:52 am Post subject: FireFly Wing Swivel Joint Repair

Jack,

The main concern I  have is your ,,,,, "If I had it to do over again,  

I would try this approach on the cage pivot stud." ,,, web page diagram.

Why do you think that would be an improvement?

On Jun 21, 2006, at 10:50 AM, Jack B. Hart wrote:

 	  Quote: 	

 <jbhart(at)onlyinternet.net>

 At 07:43 AM 6/21/06 -0400, you wrote:

> 

> <etzim62(at)earthlink.net>

 Eugene and Kolbers,

 First of all, I apologize to all who I have offended, BUT what is  

 wrong with

 providing a bearing material in a rotating joint?  Since a rotating  

 joint of

 similar material is always going to show greater wear than if one  

 surface is

 made of a bearing material, why not change it?  For less than four  

 dollars,

 I have the equivalent of a new and improved swivel joint.

 As for strength, I sent the following to another Kolber:

 "I know it looks bad but we are fortunate that Homer and/or Dennis  

 gave us a

 very robust design in this area.  The steel is 0.125 inches thick.

 ........................................  To check out the worst  

 case, the

 tangs for the clevis that attaches to the wing attachment point is  

 only

 0.875 inches wide.  By drilling the 5/16 inch ID out to 7/16 of an  

 inch you

 have a cross sectional area to support tension or compression of  

 7/16 times

 1/8. Or the equivalent of 0.055 square inches.  Unhardened 4130 has  

 a yield

 stress of 95,000 psi, so each tang will support (95,000 x -.055) 5,195

 pounds or the modified clevis will support over five tons before  

 yielding."

 Jack B. Hart FF004

 Winchester, IN

jbhart(at)onlyinternet.ne
Guest

Posted: Wed Jun 21, 2006 10:51 am Post subject: FireFly Wing Swivel Joint Repair

At 12:52 PM 6/21/06 -0400, you wrote:

 	  Quote: 	
		  



Jack,

The main concern I  have is your ,,,,, "If I had it to do over again,  

I would try this approach on the cage pivot stud." ,,, web page diagram.

Why do you think that would be an improvement?




	


Eugene,



I have used this method to get all of the play out of the aileron control up 

next to the stick.  The reason, I believe, it would be better is that it is 

simpler than what I have done.  The trick is to make the chamfer just large 

enough so that when the nut is compressed up to the plate the "O" ring is 

completely contained in the chamfer space.  This gives some compliance for 

the "O" ring to keep the clevis centered on the stud, but does not keep the 

clevis from being rotated.  And better yet, as the mating surface between 

the clevis and the cage wear, the "O" ring acts as a compressive spring and 

maintains joint tightness.  Also, if the "O" ring keeps the stud from 

touching the hole ID, there can be no wear between the stud and the clevis 

hole.



The thing to remember is that during flight these two vertical surfaces are 

in compression (drag force) and most of the lifting force is handled by the 

main spar connector and the struts, so it takes very little compressive "O" 

ring force to keep the rear spar centered/located.



Jack B. Hart FF004

Winchester, IN

jbhart(at)onlyinternet.ne
Guest

Posted: Wed Jun 21, 2006 11:05 am Post subject: FireFly Wing Swivel Joint Repair

At 01:27 PM 6/19/06 -0500, you wrote:

 	  Quote: 	
		  



.............
	


 	  Quote: 	
		  

If the bolts are snugged up tight after the wings are repositioned 

from storage to flight position, wear on these bolts and holes will 

certainly be discouraged.  If I had to fold my airplane after each 

flying session, I would insure the bolts in the universal joints were 

loose during the flight prep process, snugging them up tight prior to 

flight.  When time came to fold the airplane, a second or two to 

loosen these bolts prior to folding the wings.



John,
	




Page 15 of the FireFly assembly instruction manual, it shows the Wing 

Folding Mechanism, and it states "Do not overtighten AN5-16A bolts as 

they must be free to rotate."



Jack B. Hart FF004

Winchester, IN

n79rt(at)kilocharlie.us
Guest

Posted: Wed Jun 21, 2006 11:36 am Post subject: FireFly Wing Swivel Joint Repair

Jack,



Got to take issue with the O-rings.  (Don't like the pins either, no

worries on the strength issue just risk of breaking a cotter pin during

fold/unfold seems unnecessary considering the minuscule weight

savings...)



In Bruhn's "Analysis and design of Flight Vehicle structures" he has an

excellent example of a wing drag strut where he demonstrates that under

quite normal flight loads (high angle of attack) the drag strut will

actually be in TENSION not compression.  The forward component (in

relation to the airplane centerline)of the lift force (perpendicular to

the ground)  greatly exceeds the drag component (relative to the

airplane centerline). So the wing is actually pulling forward (i.e. drag

strut in tension)  So your o-rings are being further compressed from

actual flight loads, not just from the nut.  IF/WHEN they ever break and

fall out you will have much movement in that joint.



Jeremy

John Hauck

Joined: 09 Jan 2006
Posts: 4639
Location: Titus, Alabama (hauck's holler)

Posted: Wed Jun 21, 2006 11:38 am Post subject: FireFly Wing Swivel Joint Repair

| >If the bolts are snugged up tight after the wings are repositioned

| >from storage to flight position, wear on these bolts and holes will

| >certainly be discouraged.  If I had to fold my airplane after each

| >flying session, I would insure the bolts in the universal joints 

were

| >loose during the flight prep process, snugging them up tight prior 

to

| >flight.  When time came to fold the airplane, a second or two to

| >loosen these bolts prior to folding the wings.

| >

| John,

|

| Page 15 of the FireFly assembly instruction manual, it shows the 

Wing

| Folding Mechanism, and it states "Do not overtighten AN5-16A bolts 

as

| they must be free to rotate."

|

| Jack B. Hart FF004

| Winchester, IN



Jack:



Please reread what I wrote above.



If I was a wing folder, i.e., had to fold and unfold my Kolb to fly 

each time, I would:



-Loosen the two bolts in each universal joint during the folding and 

unfolding process.  However, I would snug them up tight once the wings 

are in position.  This will preclude the bolts and holes from wearing 

and enlarging.  Time to fold it back up.  Loosen the bolts again.



-The clevis fitting on the cage can be adjusted properly with use of 

thin and thick AN washers as required.



I can assure you, the trailing edge of the wing and the universal 

joints and clevis attachment get a work out in flight, during 

acceleration, deceleration, operation of ailerons/flaps, and when 

flying in turbulence.  Probably the most load and wear will come from 

ground ops.



Another thing to think about is wear from vibration.  Loose fittings 

tend to encourage accelerated wear.



A few things that we did to prevent this wear, based on a lot more 

than 200 hours flight time, were:



Welded steel bushings in the lift struts to fit snug in the lift strut 

attachments.  Then bolted tight to prevent wear.



No clevis pins in the wings and controls.  All bolts and nuts.



200 hours is mighty early to experience the problems you are 

experiencing with your Kolb.



One thing I have learned from building and flying these little Kolb 

airplanes, is to listen "carefully" to what others have to say, digest 

it, then either use it, store it, or throw it away.  I have learned an 

awful lot from those that have gone before me and those that have come 

after me.  I still have a lot to learn about these little Kolb 

airplanes I build, fly, and maintain.  I especially learn a lot about 

Kolbs from reading your posts.



Keep it simple.



john h

mkIII

_________________
John Hauck
MKIII/912ULS
hauck's holler
Titus, Alabama

slyck(at)frontiernet.net
Guest

Posted: Wed Jun 21, 2006 3:25 pm Post subject: FireFly Wing Swivel Joint Repair

On my MkIII I have an aluminum shim at the universal joint/cabin

interface to correct a slight sweep inaccuracy (left wing only).  Last 

year I noticed

a slight wiggle during preflight and in the spring removed it for

inspection, dabbed in a touch of anti-seize and snugged it back down.

The trick, at least on the mKIII, is to get a happy medium on tightness

due to the cotter pin hole.  The aluminum had conformed a bit  to

the mating surfaces and needed a little correction. Paint/epoxy on

the same surfaces will do the same thing.  Crank it down

pretty good and back it off to the hole and you will be fine.

I have a few hours on it since and all looks and feels well.

I don't intend to be doing a seasonal loosening/tightening exercise

with one fold per season.

-BB

On 21, Jun 2006, at 3:40 PM, John Hauck wrote:



 	  Quote: 	
		   

  | >If the bolts are snugged up tight after the wings are repositioned

 | >from storage to flight position, wear on these bolts and holes will

 | >certainly be discouraged.  If I had to fold my airplane after each

 | >flying session, I would insure the bolts in the universal joints

 were

 | >loose during the flight prep process, snugging them up tight prior

 to

 | >flight.  When time came to fold the airplane, a second or two to

 | >loosen these bolts prior to folding the wings.

 | >

 | John,

 |

 | Page 15 of the FireFly assembly instruction manual, it shows the

 Wing

 | Folding Mechanism, and it states "Do not overtighten AN5-16A bolts

 as

 | they must be free to rotate."

 |

 | Jack B. Hart FF004

 | Winchester, IN



 Jack:



 Please reread what I wrote above.



 If I was a wing folder, i.e., had to fold and unfold my Kolb to fly

 each time, I would:



 -Loosen the two bolts in each universal joint during the folding and

 unfolding process.  However, I would snug them up tight once the wings

 are in position.  This will preclude the bolts and holes from wearing

 and enlarging.  Time to fold it back up.  Loosen the bolts again.



 -The clevis fitting on the cage can be adjusted properly with use of

 thin and thick AN washers as required.



 I can assure you, the trailing edge of the wing and the universal

 joints and clevis attachment get a work out in flight, during

 acceleration, deceleration, operation of ailerons/flaps, and when

 flying in turbulence.  Probably the most load and wear will come from

 ground ops.



 Another thing to think about is wear from vibration.  Loose fittings

 tend to encourage accelerated wear.



 A few things that we did to prevent this wear, based on a lot more

 than 200 hours flight time, were:



 Welded steel bushings in the lift struts to fit snug in the lift strut

 attachments.  Then bolted tight to prevent wear.



 No clevis pins in the wings and controls.  All bolts and nuts.



 200 hours is mighty early to experience the problems you are

 experiencing with your Kolb.



 One thing I have learned from building and flying these little Kolb

 airplanes, is to listen "carefully" to what others have to say, digest

 it, then either use it, store it, or throw it away.  I have learned an

 awful lot from those that have gone before me and those that have come

 after me.  I still have a lot to learn about these little Kolb

 airplanes I build, fly, and maintain.  I especially learn a lot about

 Kolbs from reading your posts.



 Keep it simple.



 john h

 mkIII

jbhart(at)onlyinternet.ne
Guest

Posted: Wed Jun 21, 2006 4:47 pm Post subject: FireFly Wing Swivel Joint Repair

At 02:40 PM 6/21/06 -0500, you wrote:

 	  Quote: 	
		  



John,
	




All I am trying to do is improve the swivel joint so that it will not 

experience significant wear in the way I believe Homer and/or Dennis 

intended the joint to be used.  It may take another 200 or more hours to 

determine if I have indeed made an improvement or not.



In spite of your good luck at hard bolting, I am not comfortable with the 

concept.  If things are not matched up perfectly, it is possible to induce 

hidden stress by hard bolting.  I will remain with pins at all wing and 

strut attachment points.  I believe the added compliance will reduce stress 

levels in the wings, struts, and the cage.  I may have some wear problems 

but a few dollars of bushings and "O" rings will make it as good as new, and 

I can fold the wing without using a wrench.



Jack B. Hart FF004

Winchester, IN

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