Tailwheel Assy ATTACH bolts/nuts

[wingnut]

I didn't know this was a common problem. After looking at a tailwheel/leaf spring assy, I think an easy fix would be to install a dowel. The "U" channel nest pretty snug in the tailwheel assy, but is loose on the spring. If a dowel was installed in the spring, pointed up in to a hole drilled only in the "U" channel, that may prevent any pivot action. Who wants to be first?

[wingnut]

...George, we did NOT re-use the old nylon lock nut . We always replace nylon lock nuts with new, ...

OK. Well, in any case, the nylon/fiber locknut proved unsatisfactory in this application, and the strong recommendation is to replace them with steel locknuts.

Bruce, I do not believe the L-19 eyebolts contribute to this problem. (L-19's never seem to suffer excessively from this problem.) I believe the problem will be solved with the steel locknut. (At the very least, it will be better served by the steel nut.)

George, I hope you know I was just razzin ya. It is our practice to replace the nylon locks with new, but I cannot know for certain that we did

[GAHorn]

...George I didn't know you so closely monitored the pulse of L-19 maintenance issues as well as the 170.

I have had loose tailwheel-attach bolts in other aircraft, particularly C-120/140's, and those aircraft used the common AN7 bolts. I did not have such a problem with the eyebolt until this event.

Over the years, I've spent a lot of time visiting with Pete Jones and his cohorts over at the L-19 place. One of the "hottest" topics of our conversations has always been tailwheel issues and we've pretty-well covered most of the bases.
When the original part became scarce, we began casting-about for replacements (some might recall a bit of investigation Miles contributed to that effort, in the process discovering the cost-vs-difficulties issues) and Pete ended up contracting with an aircraft-hardware mfr'r with whom he had a relationship to reproduce the eyebolts IAW original specs.
Several matters came up (including one about temper of the welded part) and it was discovered why this simple part is so expensive relative to other AN hardware. Welding must be accomplished prior to plating, which must be accomplished post-annealing due to a rolled-threads issue.
In our conversations it was believed by the purveyors that the L-19 suffered no particular problem with loose eyebolts, however loose tailwheel assy's are not unique to the 170, and it was felt the culprit is usually lack-of-attention.

I personally used the eye-bolt for seven years/400+ hrs before I had the mainspring replaced. That was the second eyebolt, as I had replaced the first one shortly after acquiring my airplane (which had come with an L-19 eyebolt of unknown pedigree/cycles and we ...TIC170A... were attempting to determine a recommendation for this item.) When Del and I looked at the plating and other evidence of stress on a bolt which had suffered operational looseness, we simply decided not to take the chance on damaging my super-fast red rudder, and installed a new AN7 bolt, per the IPC, with Del's shop placing torque-seal as a witness on the bolt-head.
I plan to operate it for 200 hours and keep a close "eye" on it, before switching to another eyebolt for a similar endurance-test. I operate off a fairly smooth (NOT!) turf strip and believe it puts the assy to a good test, regularly. I'll keep everyone posted.

[cessna170bdriver]

... (some might recall a bit of investigation Miles contributed to that effort, in the process discovering the cost-vs-difficulties issues)...

Anatase Products in Tehachapi is still going strong and can manufacture just about any aircraft hardware for which a specification can be provided. I did contact them about making tailwheel eyebolts, but we never got to the cost/difficutly stage because we couldn't come up with an approved specification for making it. If there are any hard-to-find special hardware parts we need, just get me a spec and I'll get an estimate.

[KG]

Add one more to the count of a nylon lock nut on the L19 eye bolt working itself loose. Mine works loose after every two or three landings. I've obtained the steel locknut (and a new bolt) and will replace it as soon as practical.

K

[GAHorn]

Remember, that bolt should be torqued to <W R O N G - TORQUE previously listed in error>
Correction: A 7/16ths fine-thread bolt such as AN-7 should be torqued to 450-500 in/lbs.

SEE PAGE 5 OF THIS DISCUSSION THREAD FOR ANOTHER TORQUE VALUE PUBLISHED IN THE L-19 MANUAL. (Hint: 650 in/lbs.)

[wingnut]

Add one more to the count of a nylon lock nut on the L19 eye bolt working itself loose. Mine works loose after every two or three landings. I've obtained the steel locknut (and a new bolt) and will replace it as soon as practical.

K

Another loose nut installed by a wingnut ?? Is that the same nut we installed with the eyebolt a couple years ago? FYI, when George was passing thru last year on his way to the wrong Mountain View (couldn't resist George), and he alerted me to this problem, along with the new AN7 bolt, we installed a new steel lock nut AND a split lock washer. How has that worked so far George?

[wingnut]

Remember, that bolt should be torqued to 1100-1300 INCH pounds (1200 in. lbs happens to equal 100 FOOT-pounds.)

I may be wrong, but that torque seems high for a 7/16" bolt. I don't have my manual here at home. Is that a Scott spec? I know that 5/8" Bonanza wing bolts are 1300 inch pounds, but thy are a very special bolt.

[Bruce Fenstermacher]

Standard torque spec for an AN-7 in tension would be 450-500 in. lb. (37.5-41.6 ft. lb.). Of course you would calibrate that to take into account the drag of the lock nut. George, were did you get that torque?

[KG]

Add one more to the count of a nylon lock nut on the L19 eye bolt working itself loose. Mine works loose after every two or three landings. I've obtained the steel locknut (and a new bolt) and will replace it as soon as practical.

K

Another loose nut installed by a wingnut ?? Is that the same nut we installed with the eyebolt a couple years ago? FYI, when George was passing thru last year on his way to the wrong Mountain View (couldn't resist George), and he alerted me to this problem, along with the new AN7 bolt, we installed a new steel lock nut AND a split lock washer. How has that worked so far George?

Yep, that's the one. Could be that it just couldn't take it anymore after two years of my landings.
I'm parked in a place right now where I can't easily jack it to change it so I just check it often.

[wingnut]

Standard torque spec for an AN-7 in tension would be 450-500 in. lb. (37.5-41.6 ft. lb.). Of course you would calibrate that to take into account the drag of the lock nut. George, were did you get that torque?

The 450-500 in.lb. is what I was thinking too, for the AN7. But, what I need to clarify is my question to George, which should have been; Is the 1100-1300 in.lb. torque for the eyebolt (not the AN7), and if so, is it because the eyebolt is maybe an MS or NAS origin? I ask because if that is indeed the proper torque, I've been way under-torquing them, and would like the data reference.

[blueldr]

That torque sounds way too high to me. You'd have to have a pretty long handle on the wrench.

[GAHorn]

I got that torque straight out of the 100 Series Service Manual.... for a FIVE-EIGHTHS bolt... (which my eyes apparently slipped down a line (or two) due to Becks-Syndrome. Sorry.

450-500 inch lbs is the actual listed torque for that bolt. I will correct my earler gaff.

Torque Values from the Cessna Service Manual may be found in the MX Library: http://www.cessna170.org/forums/viewtop ... f=6&t=3571

[bagarre]

While out at the airport this weekend, I checked on my tailwheel which has the L-19 eye bolt and is tied out all year long.
Tight as the day I torqued it back in November with a steel lock nut.

My transponder doesn't work but the tailwheel is tight. I don't think there is a connection tho

[Robert Eilers]

This has been said by others before, but let me say it again - the value of this forum to us non A&P types is immeasurable. I have the eye bolt on my tailwheel. When I replaced the old scott with a new Bushwheel tailwheel I tightened the plastic locknut as tight as I thought it needed to be (which was pretty damn tight). However, after monitoring this discussion, I went out and torque tested the locknut. Of course, I found it loose - or at least not at 450-500 inch pounds. I have not had a problem with the tailwheel and have been paying attention to the lock nut, but this is the first time I torque tested it. I have to admit it seems awfully tight to me at 450-500 inch pounds, but what do I know. My next question is: Is the 450-500 inch pounds based on one washer, two washers, or no washers?