aileron hinge pins - snap ring instead of cotter pins?

[N74DV]

What are opinions on the .250" hinge pins of the ailerons using snap rings in a machined groove instead of cotter pins?

I use snap rings on my UAV helicopters main rotor shaft instead of a Jesus bolt and they hold up fine. The helicopters can weigh as much as 25lb.

Seems to me snap rings would be just fine on the aileron hinge pins especially considering they are under no load to speak of.

thoughts?

[Mark Julicher]

Re: aileron hinge pins - snap ring instead of cotter pins?

I'm sure they would work well and last a long time - however,

I don't know if it is a certified part. They would be hard to keep track of during field maintenance and I really don't want to stock a bunch of replacement snap rings (AKA circlips) in my tool box.

[Marv]

Re: aileron hinge pins - snap ring instead of cotter pins?

If you were parking a airplane outside or a hi moisture area they would probably rust and fall off eventualy. Stainless cotterpins do not. Just my thought. Marv

[Bird]

Re: aileron hinge pins - snap ring instead of cotter pins?

Small note on the snap rings, I am a towercrane operator, the guy that sits up on top of the high rise buildings.
On the trolly ( the part that rolls in and out to set the radius of the load), there are up to 8 boogy wheels that it travels on, and these and thier bearings are held in place with snap rings. Bearing in mind that the crane industry is watched and gouverned by numerous groups I can still not figure out how that snap ring came off and the whole damn boogy wheel fall aprox. 200 feet missing everybody on the deck.
That boogy was a side load boogy with the snap ring on top meaning no load on it, also the boogy had to slide up the post it was mounted on.
I had inspected that damn crane everyday.
I now have stickers on my hard hat that say "TRUST ME" and underneath that 1 another that says "SHIT HAPPENS".
Cotter pins won't come undone unless someone does it and alot easier to inspect visually.
This is just my rather HUMBLED opinion.

[Larry Lyons]

Re: aileron hinge pins - snap ring instead of cotter pins?

I am in the well drilling game and I echo Birds opinion. Circle clips have their place but not when my a** is in the sling. Too many ways to fail and harder to tell if they are seated properly during a visual inspection. Cotter pins, in my experience even when worn to the point of failure, still leave enough sticking out to make it difficult for the pieces to come apart. That nub will last for some time, maybe enough to see on the next preflight. Larry

[Pearson]

Re: aileron hinge pins - snap ring instead of cotter pins?

25 lb helicoper crash = hurt pride and a few $

Taylorcraft crash = YOU hurt

[N74DV]

Re: aileron hinge pins - snap ring instead of cotter pins?

looks like I have my answer.

I'm machining new oversize aileron pins (.252") from 416 stainless this week and will be sure to drill holes instead of a snap ring groove.

[astjp2]

Re: aileron hinge pins - snap ring instead of cotter pins?

Why not just buy stainless clevis pins? They do make them and they are Aircraft parts. Tim

[N74DV]

Re: aileron hinge pins - snap ring instead of cotter pins?

because they can't be obtained oversized. Our hinge bracket holes have opened up over the last 60+ years and I have no intention of replacing them and all the work involved with that. I'd rather wait until we have to recover the aircraft.

[3Dreaming]

Re: aileron hinge pins - snap ring instead of cotter pins?

DJ, is the play in the bushing or the brackets on the aileron? The problem is over the years people have replaced them with regular clevis pins instead of using the Taylorcraft pin. The Taylorcraft pin had a knurled area just under the head to keep the pin locked in the steel bracket and rotatng in the bushing. With a regular pin and poor lubrication the pin will mot rotate in the bushing, but the steel bracket rotates around the pin wearing out the bracket. The same thing happens on the tail as well. Tom

[robbie]

Re: aileron hinge pins - snap ring instead of cotter pins?

Where does one find the taylorcraft knuled pins for the tail feathers??

Robbie Robinson

Fond du Lac WI

[Guest]

Re: aileron hinge pins - snap ring instead of cotter pins?

Where does one find the taylorcraft knuled pins for the tail feathers??

Robbie Robinson

Fond du Lac WI

On the tailfeathers you can put loctite or equivalent on the end of the pin where the head is to lock in (with or without knurls).

On the aileron I do this: slightly spread the aileron hinge apart so that in order to put the cotter key in you have to squeeze the aileron hinge together to get the cotter key in the hole. Also adding a washer (thin) under the cotter key can help. The tension on the pin tends to hold it firm against the hinge so that they rotate together.
Add a drop of loctite under the circumference of the pin head too.

Dave

[robbie]

Re: aileron hinge pins - snap ring instead of cotter pins?

Thanks for the information, I got a couple of them turning on the tail feathers.

[Len Petterson]

Re: aileron hinge pins - snap ring instead of cotter pins?

Snap ring NO thanks .You never get them on and of on hinge easly and they do come off as mentioned.

[N74DV]

Re: aileron hinge pins - snap ring instead of cotter pins?

I got the new stainless pins machined and installed today. What a difference. no slop any more. I also installed the ball bearing Ralmark pulleys from the Luscombe Foundation. The ailerons control forces are reduced to a noticeable level and the total aileron system slop between pulleys and installation of the new oversized pins is reduced ALOT.