Light Aircraft Association

I need some rod ends for the aileron push rods on my project. The exact part numbers shown on the drawings (Fafnir RE 43 10 and "Uniball" F45-19 for the aileron end ) don't appear to be available now from the usual sources in the USA or the U.K.

Both ends need to have a 1/4"D hole in the "ball" end. The forward bell crank end needs to have a hollow "stem" to fit over that end of the push rod tube, which is 1/2"OD.
The aileron crank end of the push rod has a 5/16-24 threaded steel insert, to give some adjustment. I can find 1/4" ball end / 1/4 threaded female fittings in the UK, but no 1/4" ball end with a 5/16-24 thread.

There is no margin left for any further increase in weight, so I can't use a heavier tube section with threaded ends to accommodate readily available male threaded rod ends. I'd rather not reduce the size of the threaded steel inserts to 1/4" - I guess 5/16" was specified for a good reason and not just because the designer happened to have rod ends to fit that size.

So far I have tried Aircraft Spruce ( replied but can't help ), Wicks ( no response.) and several UK suppliers, without any luck.

I know nothing about the technical aspects of rod ends, but assume the loads involved with my application are not too great, although smooth and free movement is very important and they need to be reliable. Do they need to be ball bearing or would plain bearings be OK?

Any advice welcomed, along with any recommendations for suppliers of rod ends in the UK. The closest bearings I can find so far would seem to be in the region of £75 each. This seems pretty steep and I wonder if that is likely to be the norm for rod ends of acceptable utility and quality?

Ian

Is this the one?

http://www.lasaero.com/site/products/ar ... =X02QT2LGF

Shows as not held in stock but can be ordered. Bit pricey, though! The way cheaper Aurora only has the 1/4 - 28 thread.

Thanks Paul and I had discounted that one because of the cost, for the time being. Seems to have an "M" suffix to the part number - magnafluxed I assume and maybe that bumps up the price a bit.

I have just noticed that there is a very similar version available from LAS at half the price with a 5/16" thread & I had missed that one. I'll have a closer look at that and see if it would do the job. There is another suitable looking rod end in the "Medway Linkages" product list.

I'm still unable to find any rod ends that are made to push fit & be riveted to tubing. I may well have to use a threaded steel insert and a male fitting there and accept another small weight increase.

My LAA inspector is due to call tomorrow, so I'll check with him before going any further. I'd like to stick closely to the original drawings to avoid having to mess about with a formal mod. application.( A " rod mod"?)

The rod ends are attached to the push rod tubes with pairs of 1/8" aircraft rivets, so the actual loads involved in that part of the system must be quite low, otherwise there would be Boredom Fighters falling out of the sky all over the place.

Thanks again.

Ian

One of the rods on the RV-10 aileron control has a 1/2' tube with a bearing fitting on the end secured with 2 1/8 rivets. IIRC, the fitting went inside the tube. I'm at the hangar tomorrow - I'll check it out

Many thanks Paul and if you are able to confirm the rod end fitting on the RV10, that would be reassuring.

It seems that the small rivets are likely to be adequate if used on an RV.

Ian

OK, here's how it works in the RV-10 for the short run from the wing bellcrank to the aileron. The tube is a 1/2" steel with .035" walls. Into this slides a fitting (AN490HT8P) which is secured by 2 AN4-11 rivets slightly staggered at right angles. The extension is threaded - I assume 1/4" since the jam nut is AN316-4. On to this fits the bearing - F3414M. It only has a 3/16" bore but that is obviously considered adequate for what is, after all, a pretty large aircraft. I assume you could get a 1/4 - 1/4" fitting.

Hope this helps.

Thanks Paul - I'm extremely grateful to you for your help with this.

My push rod is exactly the same material as the RV and the arrangement at the aileron end is very similar. Interesting that the bore is 3/16" and this may make it easier and cheaper for me, if the smaller size could be approved. The aileron horns only have a 3mm pilot hole at the moment, so I still have time to easily change down to 3/16", if finding a larger rod end becomes a problem. I very nearly opened them out to 1/4" today, while locating the bolt holes in the aileron ribs.

The bell crank end is a bit trickier. There, the rod end fits over the tube, but I hope that I may shortly find a solution to this, thanks to an offer of assistance that appeared in my inbox the other day.

Thanks again and I soon hope to finish off my ailerons.

Ian

The aileron and elevator runs in the RV10 are both push-rod so there are various bellcranks and the like to join rods. The bearings are a mix of 3/16 and 1/4. There doesn't seem to be any logic as to why and I can't imagine the shear loads would be high enough to get anywhere near ultimate strength - can you imagine jamming the control surface and then trying to break the bolt using the control column?

This had occurred to me in this case & with other aspects, but I guess the designer may well have used what was easily available to him at that time.
I understand Don Wolf was the training Director at Grumman for much of his working life, and his wife was the personal assistant to Roy Grumman, so he would have been used to that firm's rugged building methods!

Ian