Flaperon Hinge Pin free play

[Lukeh]

I noticed free play on both outer hinges on Savannah S. 

Will I need to change bushing and pin, or could there be a more serious problem concerning metal parts of the wing and flaperons?

Anybody has done this?

[skippydiesel]

Hi Likeh,

Sorry not familiar with Savannahs, however I am anxious about the potential wear in the hinge pin design of my Sonex flight surfaces.

Still good, but only have a bit over 250hrs Hobbs.

The Sonex maintenance advice is to use a PTFE rich dry spray lubricant, on the hing mechanism. Dose Savannah recomend similar? If no, this may be a future wear mitigation strategy you could adopt.

There is a wide range of such lub's on the market .

😈

 

Edited September 15 by skippydiesel

[Lukeh]

11 hours ago, skippydiesel said:

Hi Likeh,

Sorry not familiar with Savannahs, however I am anxious about the potential wear in the hinge pin design of my Sonex flight surfaces.

Still good, but only have a bit over 250hrs Hobbs.

The Sonex maintenance advice is to use a PTFE rich dry spray lubricant, on the hing mechanism. Dose Savannah recomend similar? If no, this may be a future wear mitigation strategy you could adopt.

There is a wide range of such lub's on the market .

😈

 

Thanks, I understand using the PTFE spry is recommended now. ICP suggest "White grease, Renolit ZT2". Unfortunately I did not notice in time  and have problem on two outer flaperon hinges now. I will greese remaining hinges ASAP.

[Lukeh]

I noticed a discussion on alternative bushing, made from bearing-grade polyester (PETP-GLD130 ‘TX’  , Sustadur PET GLD 130) or such.

I was hoping some of the participants would share their experience and approach they used, as the thread contains more different paths and suggestions and not much feedback from the real use? 

 

@JG3 ,@IBob , @Kyle Communications , @facthunter , @FIL65 , @eightyknots , @dan tonner ? (sorry for spamming you) 

 

Edited September 16 by Lukeh

[Kyle Communications]

I have used the brass bushings. The biggest issue is making sure the bushings are installed correctly. The main thing is to make sure the bushing is actually working as a bush. Most from what I have seen especially with wear is the bushing is rotating in the alu hangar bracket. You can over tighten the setup. My latest build I have loctited the bushes into the right sections to make sure they cant rotate in the housing. You want the bolt only to have the bush rotating around it.

Making them from teflon or similar still has a issue if the bush is rotating. 

 

[Lukeh]

13 hours ago, Kyle Communications said:

I have used the brass bushings. The biggest issue is making sure the bushings are installed correctly. The main thing is to make sure the bushing is actually working as a bush. Most from what I have seen especially with wear is the bushing is rotating in the alu hangar bracket. You can over tighten the setup. My latest build I have loctited the bushes into the right sections to make sure they cant rotate in the housing. You want the bolt only to have the bush rotating around it.

Making them from teflon or similar still has a issue if the bush is rotating. 

 

Thanks Kyle. I am afraid you made me confused even some more. I was convinced after long thinking, that the original bushing is by the bolt fixed to one of the hangars let's say to the wing one, wing-bushing-bolt are connected and do not move, while the other hangar (flaperon) rotates around the outside of bushing aluminium on metal.

I could not get my head around this but that is how I undestood it. Not that the bolt rotates inside of the the bushing or bushing around the bolt. But you seem to suggest the later.

Edited September 17 by Lukeh

[Kyle Communications]

yes the bush is fixed and it rotates around the bolt. What most have done from what I have seen is they tighten the bolt too much so what happens is it locks into the bush and the bush rotates in the aluminium...thats not good. It wears out the bush and the hangar bracket. It con only be the bush that rotates around the bolt...just like a door hinge

Think of it this way. The bush is locked into the hanger bracket and must be fixed. the bolt head is always on the L shaped alu that is connected to the ailerons and it doesnt rotate so it must turn inside the bush when the aileron moves. If you look at the manual the bush head is always on the other side of the hangar bracket and the castellated nut is on the bigger flange of the bush. That nut needs to rotate on the head flange of that bush.

When I go to the hangar next I will see if I can do a video to explain it and show it

 

Mark

 

[Lukeh]

9 hours ago, Kyle Communications said:

yes the bush is fixed and it rotates around the bolt. What most have done from what I have seen is they tighten the bolt too much so what happens is it locks into the bush and the bush rotates in the aluminium...thats not good. It wears out the bush and the hangar bracket. It con only be the bush that rotates around the bolt...just like a door hinge

Think of it this way. The bush is locked into the hanger bracket and must be fixed. the bolt head is always on the L shaped alu that is connected to the ailerons and it doesnt rotate so it must turn inside the bush when the aileron moves. If you look at the manual the bush head is always on the other side of the hangar bracket and the castellated nut is on the bigger flange of the bush. That nut needs to rotate on the head flange of that bush.

When I go to the hangar next I will see if I can do a video to explain it and show it

 

Mark

 

Kyle I don't see it. This is from maintenance manual - the original bushing installation. The head of the screw seems to touch the bushing directly, pressing it to the left bracket. How can the screw rotate inside of the bushing? Besides, the bushing's OD is 6mm, it goes through both brackets, AN4 washer has ID 0.265 inches (6,7mm)...

This gets weirder and weirder. I probably will not understand until I dismount it and see.

I looked it up in the Italian printed construction manual now and it does not make it easier. For example they say the bushing is mounted from the inside and screw from the outside of the aircraft (always), but the brackets have different order on inside hinges to the order of outside hinges.

Edited September 17 by Lukeh

[Kyle Communications]

Thats interesting...that arrangement is different in my manual the drawing show the bolt head on the head of the bush. Yet I only have the photo in my manual the english one and from around 2011 and it appears to show the nut on the bush head.

 

Either was it doesnt matter. What ever part thee head of the bush is on that is the part the bush needs to NOT move in so really needs to be loctited if its not a press fit

 

 

[Kyle Communications]

The bolt will always need to have the bush rotate around it. Or the bush rotating around the bolt. You cant have the bush rotating through both alu parts otherwise what would be the point of having a bush you could just have a bolt through the hole

The manual for the Savannah has always been terrible

 

[Lukeh]

30 minutes ago, Kyle Communications said:

Thats interesting...that arrangement is different in my manual the drawing show the bolt head on the head of the bush. Yet I only have the photo in my manual the english one and from around 2011 and it appears to show the nut on the bush head.

 

Either was it doesnt matter. What ever part thee head of the bush is on that is the part the bush needs to NOT move in so really needs to be loctited if its not a press fit

 

 

to add to the confusion there is even different manual, showing different ICP setup. Probably older version, that JG3 have had. 

https://www.aircraftpilots.com/forums/topic/35271-improved-aileron-bushes/page/2/?&_rid=12414#findComment-447599

 

Edited September 17 by Lukeh

[Kyle Communications]

Yes in that thread the drawing Ibob did is how I have always done mine . On my original build and this rebuild as well.

John Gilpin got larger teflon bushes made but you had to ream out the hanger brackets and also the flaperon L angle mounts

 

[sfGnome]

This may possibly add more confusion (sorry if it does), but here's the hinge bolt setup on the Ventura from the latest manual chapter dated April 26. I have no idea whether it is the same as the Savannah, but the two planes are very similar in many respects. "Inner" and "Outer" in this context are referring to each flaperon, so there's 2 pointing one way and 2 the other way on each wing. On this setup, presumably the bushing is fixed in the flaperon hinge, and the bolt is fixed in the wing hinge so, as Kyle said, the bolt would be rotating inside the bush.

 

On a related point, I asked ICP about an Australian equivalent to the specified white grease, and they said "It is just a white grease, anti-corrosion, water resistant, very dense, protective.
No other relevant properties, anything used on boats it will be perfect."

[Kyle Communications]

The white grease is Lithium grease. I used to use a silicone grease years ago but now I have swapped to the Lithium.

Yes it seems now that is exactly opposite to the original way. So who knows which way is correct.

So long as the bush doesnt tun inside the alu would make the most sense. The whole idea for a bush is to have the bolt rotate inside the bush and not the bush rotate on a surface that is loaded.

The ideal would be to have a fixed bush pressed into the wing hanger bracket and another bush fixed into the flaperon bracket. A washer separator like they have where the 2 smaller parts of the bush meet. This would make more sense to me

I hope the Ventura manual is better than any of the Savannah manuals

'

 

Mark

 

[Lukeh]

9 hours ago, sfGnome said:

This may possibly add more confusion (sorry if it does), but here's the hinge bolt setup on the Ventura from the latest manual chapter dated April 26. I have no idea whether it is the same as the Savannah, but the two planes are very similar in many respects. "Inner" and "Outer" in this context are referring to each flaperon, so there's 2 pointing one way and 2 the other way on each wing. On this setup, presumably the bushing is fixed in the flaperon hinge, and the bolt is fixed in the wing hinge so, as Kyle said, the bolt would be rotating inside the bush.

 

On a related point, I asked ICP about an Australian equivalent to the specified white grease, and they said "It is just a white grease, anti-corrosion, water resistant, very dense, protective.
No other relevant properties, anything used on boats it will be perfect."

@Kyle Communications Still, in the sfGnome pictures - the extended rim of the  busher SC210 lay directly on the castle nut and screw head lay directly on the wing hinge. It would seem to me, that neither should move against each other, busher against the wing hinge, nor the screw against the busher. And flaperon hinge does move/rotate against the buhsher outside. Aluminium hole in flaperon hinge rotates on brass busher.  Explain, how this understanding is wrong?

[facthunter]

It's not a well engineered arrangement at all. Nev

[Kyle Communications]

I have the nut on the bush side on all mine but the the head of the bolt is on the inner flaperon L bracket but on the outer portion the head is on the hanger bracket. I will confirm the operation tomnorrow when I get to the hangar

 

 

[Lukeh]

As a side note, what is your take on lubricant? Many recommend PTFE  dry spray (I did order one already), ICP says lithium white grease. Which is better? Any experience on this two? I lean to the PTFE spray.

[Kyle Communications]

I used to use a silicone grease but I actually started using white lithium grease about 5 or 6 years ago. I think its better

 

Mark

 

[Lukeh]

My technical guru wants to do it other way - the one when nothing moves against the aluminium brackets - that means to have two brass tubes outer and inner, each fixed to one of the brackets, bolt going through the smaler tube (if I get it right). He says, he has done it that way before, on the Zenair STOL CH 701. I will share the details when I have some.

[Kyle Communications]

That is what I posted before in a previous post. That would be the best way to do it the issue though is you will need to manufacture double the amount of new bushes and also be very accurate on their length as you will still need a washer between the hanger bracket and the flaperon bracket

 

[Lukeh]

I have been to the airport today. On the loose hinges (the two on the outer edges of the wings) bushers tilt around the axis and they are pretty loose.
On good ones, mostly the nut and castle nut rotate together with the flaperon (but they are not fixed/tighten to the flaperon, only there is more friction, so they follow the move). I am not sure if the bushing rotates as well. 
The bushing is NOT tightly sqeezed against ANY bracket and it can not be, because the screw is tightened just against the washers, washers ID is bigger than OD of the bushing and there must be some axial free play left. Basicaly anything can rotate and nothing is fixed. Funny.
I made a video, but I am not sure if I can put it here directly, the 47MB one fails to upload.

I spoke to my technical guru, it seems he has more different ideas how to do it and have not decided yet, I must wait and see. For sure he wants to have bushing fixed to the brackets, perhaps two short bushings one from each side, bushing rim wider than the original bushing for better axial stability, pressed from outside to each bracket, possibly additionaly secured in some way against rotation.
Put the screw through it, not tight, so the bushings will rotate on the screw. Additional idea is to rivet a piece of the metal sheet to the brackets first, to make them thicker.

[facthunter]

Silicone removes Paint.. Different Metals in contact cause Galvanic  activity with water (moisture).  Brass is a poor bearing material (Copper-Zinc). Bronzes are better (Copper-TIN.) Soft materials embed dust particles, and act as a Lap. Consider stainless and hard Plastic or nylon as a a Bush. Look up what a Rose Joint is. and consider using one. Grease is an oil in a soap (stearate)  Lithium is the Most common and the colour ( RED) is Only a Dye. Anything used in a Marine environment is better.. Nev

[IBob]

My manual is Issue 1/Rev.00 1st Feb 2010 for this assembly.
It says to use:
1 bolt AN3-05, inserted outer to inner, by which I think they mean inserted with the bolt head outboard.
1 washer AN4 between the wing attachment and the aileron attachment.
1 bush SC210, inserted from inner to outer, by which I think they mean inserted with the bush flange inboard (so bolt and bush are inserted from opposite directions).
1 castle nut and cotter pin.

If this setup is not adequately tightened , then it will tilt under load, resulting in wear to the bush and holes.

 

I think the correct method of tightening (regardless of how many washers etc) is as posted above by Lukeh (7.3 Control Surface Hinges).

 

I tightened mine in a similar fashion, first nipping them up tight, then backing the nut off one castle. I then checked that I could rotate the bolt by hand, but without excessive play. And I rechecked that at service intervals.

[facthunter]

IF you back it off, it can tilt and turn in the Hole. Its NOT meant to.. It's meant to turn on the bush. Nev