Page 6 of 7 FirstFirst ... 4567 LastLast
Results 201 to 240 of 241

Thread: Broken Tail wheel bolt

  1. #201
    cubdriver2's Avatar
    Join Date
    Apr 2003
    Location
    upstate NY
    Posts
    10,873
    Post Thanks / Like
    I'm no engineer, far from it. It bothers me that a regular AN bolt lasts longer then one of these eyebolts, a lot longer. I'm a glass guy and if you put a cutout in glass it's got to be a radiused angle and not have anything close to a square corner or it will eventally stress break. I spent the first half of my life trying to destroy farm equiptment and broke and had to repair what I had to keep working, I changed a ton of bolts on things that should not have broken but I'm still no engineer, but I have fixed a lot of stuff that lasted longer then what the engineer first gave me. I still think that that eyebolt has flaws because it is an eye and a bolt made from one chunk of steel with the weakest link where the two meet, at the corner. I think that the eye " nut " and an AN bolt would be twice or more as strong because the bolt continues into the nut without the stress riser that the machined eyebolt has. Just a guess and all of it OPINION. Just trying to help

    Glenn

  2. #202
    Steve Pierce's Avatar
    Join Date
    Mar 2002
    Location
    Graham, TX
    Posts
    21,316
    Post Thanks / Like
    Glenn, Do you hear about all the broken AN bolts?
    Steve Pierce

    Everybody is ignorant, only on different subjects.
    Will Rogers

  3. #203
    cubdriver2's Avatar
    Join Date
    Apr 2003
    Location
    upstate NY
    Posts
    10,873
    Post Thanks / Like
    Quote Originally Posted by Steve Pierce View Post
    Glenn, Do you hear about all the broken AN bolts?
    Good point, nobody whines when it's a buck and a half bolt. But I have 2 SC guys here that both have rocky strips and one has over 300 hr on rocks and rough ice when on skis with an AN bolt, and the other can't remember when it was last changed ?

    Glenn
    Last edited by cubdriver2; 08-31-2012 at 01:08 PM.

  4. #204
    nanook's Avatar
    Join Date
    Aug 2002
    Location
    northern alaska
    Posts
    1,741
    Post Thanks / Like
    Just changed out a 3200 Scott to a Bushtailwheel kit on a PA-12. It was converted to a -8 bolt in the Scott head and uses a 1-1/4" 4 spring .... -8 bolt was not tight and bent...aluminum Scott head fretting under -8 washer under the bolt head. Hard to keep torque when you have steel on aluminum working. I would rather have that -8 bolt getting bent than a -7 subjected to the same stresses...

  5. #205
    Darrel Starr's Avatar
    Join Date
    Jan 2003
    Location
    Plymouth, MN
    Posts
    2,524
    Post Thanks / Like
    I bought some AN8-21 bolts but thought I would wait for the Bushwheel recommendation in case this would lead to some other problem. Off hand, the AN8 looks like a good insurance policy -- just wondering if Wup has an argument against using it. Also, for the hard washers, what is a good source -- a really good hardware store? or some other supplier?

  6. #206
    Gordon Misch's Avatar
    Join Date
    Dec 2003
    Location
    Toledo, Wa (KTDO)
    Posts
    3,901
    Post Thanks / Like
    Your local Cat dealer. Really!
    Gordon

    N4328M KTDO

  7. #207
    Darrel Starr's Avatar
    Join Date
    Jan 2003
    Location
    Plymouth, MN
    Posts
    2,524
    Post Thanks / Like
    Fine, but the CAT washers are very thick. Would probably change the weight & balance. Guess I will try the John Deere dealer.

  8. #208
    Aviator's Avatar
    Join Date
    Jun 2002
    Location
    Canada (Legally)
    Posts
    1,398
    Post Thanks / Like
    McMaster-Carr has 1/2 " titanium washers @ $7.50. About the same strength as 18-8 SS.
    http://www.mcmaster.com/#standard-flat-washers/=j47u7l

  9. #209
    Darrel Starr's Avatar
    Join Date
    Jan 2003
    Location
    Plymouth, MN
    Posts
    2,524
    Post Thanks / Like
    I keep coming back to the idea that the yielded AN washers is trying to tell us something. And since I believe that the AN washers are capable of being resilient up to the load that will yield the bolt, the yielded washers indicate that the bolt too is being overloaded.
    However, if the bushing is removed for installation of an AN8 bolt, then the load that used to be carried by the bushing between the springs and bolt head will have to be carried by the softer aluminum housing. If the AN washer was yielding then without the bushing, it seems the aluminum housing will yield even more. So the hard washers won't yield but the housing will. I'm thinking that an AN7 bolt with bushing is a better combination than transmitting all the load through the aluminum housing without the bushing.
    A better design might be a much thicker hard bushing, say 3/16 wall with a 1/2 ID pressed into the aluminum housing so a larger AN8 can be used but with a substantial load path in hard steel from the bolt head to the springs. I just don't know if there is enough "meat" in the aluminum housing to also keep the housing sound.
    For reference, here is the housing with an AN7 bolt.
    Click image for larger version. 

Name:	P1060725a.jpg 
Views:	143 
Size:	203.3 KB 
ID:	8476
    Last edited by Darrel Starr; 09-02-2012 at 07:49 PM.

  10. #210
    Aviator's Avatar
    Join Date
    Jun 2002
    Location
    Canada (Legally)
    Posts
    1,398
    Post Thanks / Like
    A lot of different values are mentioned in this thread. Here are a few I find useful. (You might want to check my math, though.)

    The yield strength of AN bolts is 90,000 psi. (125,000 psi is the minimum ultimate tensile strength.)
    Preload bolts to not more than than 75% of bolt's yield strength.

    The tensile stress area of a 7/16-20 bolt = 0.1187sq.in.
    Preload AN7 bolts to (90,000 x 0.1187 x .75 =) 8012 lbs.
    55 lb.ft (dry) torque = 7550 lbs (clamping force).

    The tensile stress area of a 1/2-20 bolt = 0.1599 sq.in.
    Preload AN8 bolts to (90,000 x 0.1599 x .75 =) 10,793 lbs.
    90 lb.ft (dry) torque = 10,700 lbs (clamping force).

    7075-T6 forgings (if that's what Scott uses) have a yield strength of around 65,000 psi. That means it should not deform below about 9,750 lbs. using 5/8 O.D x 7/16 I.D. washers (washer area .30-.15 x 65,000), which is more than the clamping force applied by a preloaded AN7 bolt. Or, using 1/2 bolts and 11/16 O.D x 1/2 I.D. washers (washer area .37-.20 x 65,000) 11,050, which is also more than the clamping force applied by a preloaded AN8 bolt. 'Course, the steel bushing complicates matters, but maybe someone else will wrestle with that.

    If you can keep the tensile load on an AN7 bolt under 8,000 lbs. neither the bolt nor the forging will be overstressed. This translates to about 80 lbs on the tailwheel @ 10G's x leverage. If the leverage is - for the sake of simplicity - say, 10:1 (tailwheel center to bolt to end of forging), then this should amount to about 8,000 lbs. Exceed the weight on the tailwheel or the G's when you slam the tail down and something will get overstressed.

  11. #211
    skywagon8a's Avatar
    Join Date
    Mar 2008
    Location
    SE Mass
    Posts
    11,484
    Post Thanks / Like
    There has been a lot of good engineering data presented on this broken bolt subject. Do you suppose that the problem with the bolts breaking is strictly piloting technique? Do all of the planes which have had bolts break have VGs installed? Since the VGs allow the wing to go to a higher angle of attack before stalling then it stands to reason that the tail wheel would be the first to touch down. The tail wheel assembly has far less shock absorbing capabilities than the main gear with bush tires. So, if the tail wheel is taking all of the initial landing loads in the rough terrain that I assume that the plane is landing on, then it must be taking a terrific beating before the main gear touches. The tail wheel is only supposed to take taxi loads not hard pounding in rock piles. Remember that some of the early planes only had an ax handle tied on with bungee cord to support the tail.
    N1PA

  12. #212
    Tim's Avatar
    Join Date
    Feb 2002
    Location
    Petersburgh, NY
    Posts
    3,547
    Post Thanks / Like
    "There has been a lot of good engineering data presented on this broken bolt subject. Do you suppose that the problem with the bolts breaking is strictly piloting technique? "

    No

  13. #213
    spinner2's Avatar
    Join Date
    Dec 2006
    Location
    Montana
    Posts
    1,859
    Post Thanks / Like
    Quote Originally Posted by skywagon8a View Post
    There has been a lot of good engineering data presented on this broken bolt subject. Do you suppose that the problem with the bolts breaking is strictly piloting technique? The tail wheel assembly has far less shock absorbing capabilities than the main gear with bush tires. So, if the tail wheel is taking all of the initial landing loads in the rough terrain that I assume that the plane is landing on, then it must be taking a terrific beating before the main gear touches. The tail wheel is only supposed to take taxi loads not hard pounding in rock piles. Remember that some of the early planes only had an ax handle tied on with bungee cord to support the tail.
    That is why Cub pilots like to wheel land in rough stuff and why 3" extended gear is popular.



    Sent from my iPhone from the middle of nowhere using Tapatalk
    "Fast is fine, but accuracy is everything." Wyatt Earp

  14. #214
    musket's Avatar
    Join Date
    Mar 2003
    Location
    Baja Oklahoma
    Posts
    279
    Post Thanks / Like
    Any more information on these eyebolts?

  15. #215
    Bill Ingerson's Avatar
    Join Date
    Jan 2004
    Location
    Snohomish Washington
    Posts
    1,433
    Post Thanks / Like
    We rebuilt my tailwheel and installed all of the springs instead of just three in the head assembly. I have put in about 30 hours on it now and everything is tight, checked it yesturday with the tail wheel off the ground and a jack. I have the BushWheel eye bolt and so far, no problem at all. The bolt looks good.
    I try to taxi with the stick forward to keep all the weight off the tail that I can, also two wheel landings most of the time and let the tail down at the very last of my landing. Knock on Wood, no problems.

  16. #216
    cpthazard's Avatar
    Join Date
    May 2002
    Location
    Planet Utah
    Posts
    215
    Post Thanks / Like
    you can always get a two hole upper casting from Mr. Wup, Pawnee Tail springs from Univair, use the eye bolt and a standard AN 7, these puny little Scott Tailwheels take one hell of a pounding, it's amazing to me they last as long and work as well as they do. My tail is 3 pounds heavier than anyone elses but I've never had a tailwheel issue, unless you count the one that got away out over the wilds between Sitka and Hoonah and that had nothing to do with Eye Bolts....more to do with a mentally defective mechanic who forgot a cotter pin on the center pivot ......I'll be at JC check it out, just look for the old StuporKub

  17. #217

    Join Date
    Sep 2014
    Location
    Fairvew East (Crane Road Airstrip),Wasilla, AK
    Posts
    26
    Post Thanks / Like
    I am a new member to sc.org and this thread was my initiation into your community. It was awesome! I discovered you because I was forced into some online investigation by some repeated Scott 3200 tail wheel issues and the need to increase my maintenance skills. The overall intelligent and mature yet jovial exchanges here are encouraging. Every other "blog" sort of site I have ever seen soon deteriorated into rants and useless opinion. Kudos to you all. Alex
    PS - I would start another interesting thread but it is 1:54 AM. I do not like to be sleepy when I pilot my 1948 "pick-up truck" PA-14.

  18. #218
    N5126H's Avatar
    Join Date
    Feb 2003
    Location
    Anchorage, Alaska
    Posts
    630
    Post Thanks / Like
    Quote Originally Posted by salex View Post
    I am a new member to sc.org and this thread was my initiation into your community. It was awesome! I discovered you because I was forced into some online investigation by some repeated Scott 3200 tail wheel issues and the need to increase my maintenance skills. The overall intelligent and mature yet jovial exchanges here are encouraging. Every other "blog" sort of site I have ever seen soon deteriorated into rants and useless opinion. Kudos to you all. Alex
    PS - I would start another interesting thread but it is 1:54 AM. I do not like to be sleepy when I pilot my 1948 "pick-up truck" PA-14.
    Not a pick-up-truck! A station wagon maybe.

  19. #219

    Join Date
    Sep 2014
    Location
    Fairvew East (Crane Road Airstrip),Wasilla, AK
    Posts
    26
    Post Thanks / Like

    Pick-up or Station Wagon PA 14

    True. 5192H, Serial# 512. But I make mine work like a truck.

    My issue with my Scott 3200 is the continual loosening of the tailwheel bolt. I am running the Gar Aero wide fork with standard Scott head on a Pawnee spring using the standard AN 7 bolt and lock nut. I was keeping close eye on it because we had just put in some new internal parts at annual. (Trying all five little internal springs this time - contrary to popular advice.) After every few landings at all my off-pavement places, it will have loosened enough to be detectable by a small amount of play between the whole tailwheel assembly and the spring. I have never seen any mechanic go at my tailwheel with their torque wrench - maybe I just never saw it - and verbal instruction has always been along the line of "good and tight" - so maybe the various torque figures given here are the answer. I can't say this thread really answered my questions, added to them in fact, but it sure helped me think through some issues.

  20. #220
    mike mcs repair's Avatar
    Join Date
    Aug 2004
    Location
    chugiak AK
    Posts
    11,773
    Post Thanks / Like
    Quote Originally Posted by salex View Post
    .. But I make mine work like a truck......
    trust me, he beats it.... bent it right in half and bent wing the one time when the goofy 4" wheel adaptors came apart... nothing fun like trying to gas weld in a 30 kt wind...

  21. #221
    Steve Pierce's Avatar
    Join Date
    Mar 2002
    Location
    Graham, TX
    Posts
    21,316
    Post Thanks / Like
    Is the bushing in the head where the bolt attaches to the spring?
    Steve Pierce

    Everybody is ignorant, only on different subjects.
    Will Rogers

  22. #222

    Join Date
    May 2014
    Posts
    839
    Post Thanks / Like
    Quote Originally Posted by Tim View Post
    "There has been a lot of good engineering data presented on this broken bolt subject. Do you suppose that the problem with the bolts breaking is strictly piloting technique? "

    No
    Pilot technique?
    Thought the TW bolt held up remarkably, was a little dissapointed with performance of the inner tube though....
    Click image for larger version. 

Name:	tailwheel.png 
Views:	173 
Size:	280.9 KB 
ID:	17070

  23. #223
    RaisedByWolves's Avatar
    Join Date
    Feb 2005
    Posts
    4,539
    Post Thanks / Like
    Quote Originally Posted by Oliver View Post
    Pilot technique?
    Thought the TW bolt held up remarkably, was a little dissapointed with performance of the inner tube though....
    Click image for larger version. 

Name:	tailwheel.png 
Views:	173 
Size:	280.9 KB 
ID:	17070
    Whats the story?

  24. #224

    Join Date
    Sep 2014
    Location
    Fairvew East (Crane Road Airstrip),Wasilla, AK
    Posts
    26
    Post Thanks / Like
    Ha! I chuckled at the "trust me" part, Mike - until I remembered some of us have been trusting you - with our lives - for a long time!!

    Say, you are hard to get hold of. Still got the same phone #? I have a question to see if you remember why we did a certain thing the last lime we put that tailwheel together.

  25. #225

    Join Date
    Dec 2006
    Location
    Meanwhile,...
    Posts
    5,462
    Post Thanks / Like
    Quote Originally Posted by Oliver View Post
    Pilot technique?
    Thought the TW bolt held up remarkably, was a little dissapointed with performance of the inner tube though....
    Click image for larger version. 

Name:	tailwheel.png 
Views:	173 
Size:	280.9 KB 
ID:	17070
    I'm no expert but I'd say that was more of a Hippy Hippy Shake than a Shimmy!
    Remember, These are the Good old Days!

  26. #226

    Join Date
    Sep 2014
    Location
    Fairvew East (Crane Road Airstrip),Wasilla, AK
    Posts
    26
    Post Thanks / Like
    Hello Steve,
    It wasn't - but is now. It apparently got left out the last time it was off. And I do not remember if I was the one who put it on that time or if it was "the help." It does have the issue of protruding through a bit too far - as was pictured earlier in the thread - which makes me a little nervous. Is it actually supposed to do that? The old original/small 3200 that came on the plane when I got it - and had not been off in a long time - actually had that bushing stuck inside the head. No one who saw it seemed to be concerned about it. I still have that old head to clean up and have ready for use. I have wondered about it because there was a bit of rust on the lower end of that bushing. I was thinking of how to get it out and replace it without damaging the aluminum head. Alex

  27. #227

    Join Date
    May 2014
    Posts
    839
    Post Thanks / Like
    Quote Originally Posted by RaisedByWolves View Post
    Whats the story?
    3 point landing in tall grass, caught a rock with the TW. (another reason not to 3pt)
    my mechanic suggested blowing the wrinkles out of the rudder with a heat gun and leaving it as is. He thought it looked pretty cool as a "long travel tailwheel mod"

  28. #228
    Steve Pierce's Avatar
    Join Date
    Mar 2002
    Location
    Graham, TX
    Posts
    21,316
    Post Thanks / Like
    If it is astandard spring the bushing will fit into the adapter but if using a Bushwheel or Pawnee spring I turn the bushing down so it is only as deep as the head. The bushings come out pretty easy with a bushing driver.
    Steve Pierce

    Everybody is ignorant, only on different subjects.
    Will Rogers

  29. #229

    Join Date
    May 2014
    Posts
    839
    Post Thanks / Like
    Bit of a thread drift.
    Came across this photo, thought id circulate it again as a reminder to check torque on wheel bolts occasionally too.
    Assuming thats what lead to rotor falier.


    Click image for larger version. 

Name:	cleavland rotor failure.JPG 
Views:	117 
Size:	109.7 KB 
ID:	17071

  30. #230
    cubdriver2's Avatar
    Join Date
    Apr 2003
    Location
    upstate NY
    Posts
    10,873
    Post Thanks / Like
    Quote Originally Posted by Oliver View Post
    3 point landing in tall grass, caught a rock with the TW. (another reason not to 3pt)
    my mechanic suggested blowing the wrinkles out of the rudder with a heat gun and leaving it as is. He thought it looked pretty cool as a "long travel tailwheel mod"
    You can make some loops with .041 safety wire by curving it and poking holes in the fabric close to bent lower tube. And with a slide hammer hooked in the loops pull the tube back closer to where it started. That way you have less fabric to shrink.

    Glenn

  31. #231
    mike mcs repair's Avatar
    Join Date
    Aug 2004
    Location
    chugiak AK
    Posts
    11,773
    Post Thanks / Like
    Quote Originally Posted by Oliver View Post
    Bit of a thread drift.
    Came across this photo, thought id circulate it again as a reminder to check torque on wheel bolts occasionally too.
    Assuming thats what lead to rotor falier.


    Click image for larger version. 

Name:	cleavland rotor failure.JPG 
Views:	117 
Size:	109.7 KB 
ID:	17071

    torque is not gonna prevent that....

    but adding the "kidney" shaped washers will help

  32. #232
    Steve Pierce's Avatar
    Join Date
    Mar 2002
    Location
    Graham, TX
    Posts
    21,316
    Post Thanks / Like
    Cajun Joe used a slide hammer in a similar situation on my recomendation however he let me know that I did not forwarn him about keeping the skin between his thumb and pointer finger out from between the slide and the hammer. He had me in stitches when he called to tell me about his misadventure.
    Steve Pierce

    Everybody is ignorant, only on different subjects.
    Will Rogers

  33. #233

    Join Date
    May 2014
    Posts
    839
    Post Thanks / Like
    Quote Originally Posted by cubdriver2 View Post
    You can make some loops with .041 safety wire by curving it and poking holes in the fabric close to bent lower tube. And with a slide hammer hooked in the loops pull the tube back closer to where it started. That way you have less fabric to shrink.

    Glenn
    I opted to strip it and weld in a new bottom section.
    Great advise for field repair, doubt I'll be adding a slide hammer to my tool kit though.

  34. #234

    Join Date
    May 2014
    Posts
    839
    Post Thanks / Like
    Quote Originally Posted by mike mcs repair View Post
    torque is not gonna prevent that....

    but adding the "kidney" shaped washers will help

    It was installed with kidney washers, they were neatly nestled under the bolt heads still.
    I assumed holes got hogged out from the rotor wallowing around

  35. #235
    cubdriver2's Avatar
    Join Date
    Apr 2003
    Location
    upstate NY
    Posts
    10,873
    Post Thanks / Like
    Quote Originally Posted by Steve Pierce View Post
    Cajun Joe used a slide hammer in a similar situation on my recomendation however he let me know that I did not forwarn him about keeping the skin between his thumb and pointer finger out from between the slide and the hammer. He had me in stitches when he called to tell me about his misadventure.
    Better not let him split wood with a wedge and a sledge either.

    Glenn

  36. #236
    JP's Avatar
    Join Date
    Mar 2003
    Location
    The Big Woods of Maine
    Posts
    3,302
    Post Thanks / Like
    I can publicly state that RaisedByWolves is an expert on the Scott 3200. He also has a unique taxi test to determine how the tailwheel is performing.
    JP Russell--The Cub Therapist
    1947 PA-11 Cub Special

  37. #237
    mike mcs repair's Avatar
    Join Date
    Aug 2004
    Location
    chugiak AK
    Posts
    11,773
    Post Thanks / Like
    Hi Steve,

    Quote Originally Posted by salex View Post
    ...Say, you are hard to get hold of. Still got the same phone #? ...
    yes, i rarely ever turn Phone on now, or answer it, or return calls...

    Quote Originally Posted by salex View Post
    ...I have a question to see if you remember ...
    that was over? decade+ ago, I don't remember now..

    or what tool I walked across shop today to grab anymore

  38. #238
    RaisedByWolves's Avatar
    Join Date
    Feb 2005
    Posts
    4,539
    Post Thanks / Like
    Quote Originally Posted by JP View Post
    I can publicly state that RaisedByWolves is an expert on the Scott 3200. He also has a unique taxi test to determine how the tailwheel is performing.

    And i can say that you shouldn't use a nylon lock nut where a cotter pin is required. "man this thing doesn't turn worth a damn"

  39. #239
    cubdriver2's Avatar
    Join Date
    Apr 2003
    Location
    upstate NY
    Posts
    10,873
    Post Thanks / Like
    Quote Originally Posted by JP View Post
    I can publicly state that RaisedByWolves is an expert on the Scott 3200. He also has a unique taxi test to determine how the tailwheel is performing.
    Quit your whining, we had you on your way in short order after we robbed some parts from one of the local yokels.

    Glenn

  40. #240
    JP's Avatar
    Join Date
    Mar 2003
    Location
    The Big Woods of Maine
    Posts
    3,302
    Post Thanks / Like
    Quote Originally Posted by cubdriver2 View Post
    Quit your whining, we had you on your way in short order after we robbed some parts from one of the local yokels.

    Glenn
    I still laugh about that one. Especially when we walked out and found the wheel assembly right at the end of a gouge in the runway. And I got to ride in a shiny, new Husky back to the WAD!
    JP Russell--The Cub Therapist
    1947 PA-11 Cub Special

Similar Threads

  1. Broken tail wheel leaf spring
    By hooligan in forum Everything Else (formerly:My Other Plane Is A....)
    Replies: 3
    Last Post: 07-13-2010, 06:27 PM
  2. Scott 2600 wheel bolt torque?
    By cubist in forum Cafe Supercub
    Replies: 0
    Last Post: 03-17-2007, 08:14 AM
  3. Tail-wheel bolt - 4 leaf springs
    By PhillipsRC in forum Cafe Supercub
    Replies: 3
    Last Post: 09-22-2006, 10:12 PM

Bookmarks

Bookmarks

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •