Tailwheel spring clamp

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N2782C
Posts: 100
Joined: Fri Mar 16, 2007 1:37 am

Tailwheel spring clamp

Post by N2782C »

I had the U bolt clamp on the tailwheel spring snap one nut off on a normal landing the other day. The immediate result was a fairly violent turn off the runway and out into the grass. I'm sure a ground loop would have followed had I not max braked the right brake to stop the turn. The good news was, and lucky it was, that the U bolt did not completerly fall off but instead stuck to the side of the spring thus preventing the total caster from left to right of the tailwheel. Upon inspection of the U bolt it occurred to me that it is a mighty puny piece of equipment to be holding the tailwheel assemble in the spring track. My question is this: does anyone make a heftier U bolt and clamp for the Scott 3220 tailwheel? A friend of mine, in the aluminium tank business and current 170 owner has replaced his with his own stainless steel U bolt clamp. He says that on a hardness scale it is stronger than the steel one supplied by Cessna or Scott. Any comments?

Also, on another item, does the main bolt that holds the top of the tailwheel spring onto the fuselage, when tightened properly, and with the tailwheel off the ground, still allow some minor up and down play on the spring itself or should it be tight with no play at all?

Thanks.
Semper Fi

'54 C-170B N2782C
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GAHorn
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Re: Tailwheel spring clamp

Post by GAHorn »

If your U-bolt snapped it may be due to excessive flex allowed by that loose AN6-22A bolt which holds the spring stack (and which should be torqued to 160-190 in. lbs.) Such looseness will allow the spring-stack to move, and if it didn't crack your PN 0510000-31 channel (B-IPC, Fig 29, item 8) then you were lucky.
Cessna gets an outrageous price for that PN 0642133 U-bolt. Our supplier is very affordable. I PM'd you his contact info.
Alternatively you can use a pair of AN4 bolts and another 0510000-33 stiffener such as used at the upper end of the U-bolt, but the U-bolt does a better job of capturing the springs laterally.
'53 B-model N146YS SN:25713
50th Anniversary of Flight Model. Winner-Best Original 170B, 100th Anniversary of Flight Convention.
An originality nut (mostly) for the right reasons. ;)
voorheesh
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Joined: Tue Jan 04, 2005 5:22 am

Re: Tailwheel spring clamp

Post by voorheesh »

Any chance someone could answer the question about up and down play in the tailwheel spring when the tail is off the ground?
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bsdunek
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Re: Tailwheel spring clamp

Post by bsdunek »

Mine does not have any play at the upper attachment. There is some movement as the spring is captured between two rubber pads captured in metal channels. I would check the condition of these pads, as they may be deteriorated. I replaced mine some years ago with sheet neoprene from McMaster-Carr (http://www.mcmaster.com/). I forget the thickness, but I think it was 3/16, 60 Shore A.
This is what you want:
High-Strength Multipurpose Neoprene Rubber
Offers an ideal balance of increased strength, and good resistance to oil, flame, weather, and abrasion even with rough handling.


I cut from the sheet with large tin snips and cut the hole with a punch from a gasket cutting tool. Use the old ones as patterns.

Just the way I did it, and it worked fine.
Bruce
1950 170A N5559C
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GAHorn
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Re: Tailwheel spring clamp

Post by GAHorn »

Aircraft with the earlier steel "box" tailwheel bracket uses the "pads" such as you described, Bruce, and yours is a good solution.
The later, large, aluminum "fishmouth" bracket does not use those pads. There is only one shim made of steel. The B model IPC pages 53 and 54 illustrate.
No appreciable vertical movement is normal in the spring stack except thru flex of the springs.
'53 B-model N146YS SN:25713
50th Anniversary of Flight Model. Winner-Best Original 170B, 100th Anniversary of Flight Convention.
An originality nut (mostly) for the right reasons. ;)
derf62
Posts: 91
Joined: Wed Apr 24, 2002 4:07 pm

Re: Tailwheel spring clamp

Post by derf62 »

Speakiing of part number fig 29. , Index -8, 0510000-31. Can anyone tell me if this part can be replaced w/o vertical fin removal. This is what the guys told me at the Sun N Fun 170 seminar. " I needed to remove the vertical fin to get at the two bolts facing forward towards the nose of the acft. Your input appreciated.

FRED
N2782C
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Re: Tailwheel spring clamp

Post by N2782C »

Fred,

I'm in the process of trying to replace these two bolts as I write this. I think, and am shortly going to find out, if it can be done thru the elevator push rod opening after disconnecting the push rod. It's only about 6 inches from the opening to the bolts but it's going to take some fancy dancing to do the job.
Semper Fi

'54 C-170B N2782C
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johneeb
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Re: Tailwheel spring clamp

Post by johneeb »

derf62 wrote:Speakiing of part number fig 29. , Index -8, 0510000-31. Can anyone tell me if this part can be replaced w/o vertical fin removal. This is what the guys told me at the Sun N Fun 170 seminar. " I needed to remove the vertical fin to get at the two bolts facing forward towards the nose of the acft. Your input appreciated.

FRED
Fred,
I replaced that bracket last year without removing any part of the tail group. I cannot recall if I worked though the push rod tube slot or the bulkhead with an extra long extension.
Johneb
John E. Barrett
aka. Johneb

Sent from my "Cray Super Computer"
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DaveF
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Re: Tailwheel spring clamp

Post by DaveF »

AN6-22A bolt which holds the spring stack (and which should be torqued to 160-190 in. lbs.)
George,

Is that torque a Cessna spec or a standard AN6 value?

Dave
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GAHorn
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Re: Tailwheel spring clamp

Post by GAHorn »

Did you check the standard torque tables before you asked that question? Image

Standard Torque Table: http://www.cessna170.org/forums/viewtop ... f=6&t=3571 :wink:
'53 B-model N146YS SN:25713
50th Anniversary of Flight Model. Winner-Best Original 170B, 100th Anniversary of Flight Convention.
An originality nut (mostly) for the right reasons. ;)
N2782C
Posts: 100
Joined: Fri Mar 16, 2007 1:37 am

Re: Tailwheel spring clamp

Post by N2782C »

I had an IA stop up today and take a look at my replacement plans for the spring receiver on my 170B. While he said that if he were to do it , for liability reasons, he would take the tail off and secure the two bolts thru the opening just above the bolts. He also said that it is perfectly legal to secure the front of the receiver with cherry max rivets, which we did. He also suggested, since there were a couple of bolt holes in the old receiver and aft fuselage part that it attaches to were a bit elongated, that we drill out the 3/16th bolt holes to 7/32nds and then ream the holes with a 1/4 inche reamer and follow that up by using 1/4 inch AN4-4A bolts and nuts to secure the spring receiver to the aft fuselage. We did that today. The spring is now attached to the airplane and after a tire change tomorrow we plan on flying it.
Semper Fi

'54 C-170B N2782C
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GAHorn
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Re: Tailwheel spring clamp

Post by GAHorn »

N2782C wrote:I had an IA stop up today and take a look at my replacement plans for the spring receiver on my 170B. While he said that if he were to do it , for liability reasons, he would take the tail off and secure the two bolts thru the opening just above the bolts. He also said that it is perfectly legal to secure the front of the receiver with cherry max rivets, which we did. He also suggested, since there were a couple of bolt holes in the old receiver and aft fuselage part that it attaches to were a bit elongated, that we drill out the 3/16th bolt holes to 7/32nds and then ream the holes with a 1/4 inche reamer and follow that up by using 1/4 inch AN4-4A bolts and nuts to secure the spring receiver to the aft fuselage. We did that today. The spring is now attached to the airplane and after a tire change tomorrow we plan on flying it.
What he's referring to isn't a "retainer" ... but is the "Channel- tailwheel spring retainer" , IPC-B, Fig 25, item 36, PN 0510000-31. :wink:
He's replaced the items 40 (AN3 bolt) and 41 (AN365 nut) with larger bolts/nuts, instead of using cherrymax rivets in that location.
Another method to repair elongated holes is to ream, bush, and then install original sized hardware.
'53 B-model N146YS SN:25713
50th Anniversary of Flight Model. Winner-Best Original 170B, 100th Anniversary of Flight Convention.
An originality nut (mostly) for the right reasons. ;)
jakedunn
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Joined: Fri Jun 10, 2011 7:13 pm

Re: Tailwheel spring clamp

Post by jakedunn »

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Last edited by jakedunn on Tue Jul 05, 2011 3:09 pm, edited 1 time in total.
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GAHorn
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Re: Tailwheel spring clamp

Post by GAHorn »

jakedunn wrote:My u-bolt broke off just as the above did and I could use some help finding a replacement if anyone has a source. Thanks.
Jake, Cessna charges $138.00 for that U-bolt. If I told you where you could get one for less than 1/3rd that price.... would it show you what a great benefit membership in this association is? :wink:

(Air Repair, Inc. will give you a 170 association discount if you have your membership number handy. You can join at the home page of this website, or by email at headquarters@cessna170.org .)
'53 B-model N146YS SN:25713
50th Anniversary of Flight Model. Winner-Best Original 170B, 100th Anniversary of Flight Convention.
An originality nut (mostly) for the right reasons. ;)
jakedunn
Posts: 8
Joined: Fri Jun 10, 2011 7:13 pm

Re: Tailwheel spring clamp

Post by jakedunn »

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