Tail wheel bolt- Scott

rudymantel · Post by **rudymantel** » Thu Aug 04, 2005 2:32 am

Last week I was enjoyng my favorite recreation, doing touch & goes.
All went swimmingly well until the last landing, a full stop. When the tail wheel came down, the airplane swerved to the left. I straightened it, but thought- how clumsy of me. (there was a 10 knot 45 degree crosswind from the right !).
A few days later I took my grandchldren for a lttle flight and on landng the same thing happened. Hmmm... So I decided to check my tailwheel. The pressure was low- only about 20 psi- and the bolt holdng the tailwheel to the main spring was slightly loose! The curious thing is that this bolt was tightened at the last annual (I think) and it is held by a castillated nut and a cotter pin. You wouldn't think it could come loose- it wasn't very loose- maybe 3/4 turn tightened it.
That's a pretty heavy bolt, and the only way I think it could have loosened was by the bolt stretching slightly.
I always make wheel landings and the tailwheel s treated very gently.
Has anyone else had a similar experience ?
Rudy

johneeb · Post by **johneeb** » Thu Aug 04, 2005 3:04 am

Rudy,
Did tightening up the mounting bolt solve the swerving problem

Johneb

rudymantel · Post by **rudymantel** » Thu Aug 04, 2005 2:05 pm

John, I haven't flown the airplane since tightening the bolt. Have a trip scheduled for tomorrow and will know then.
Rudy

jrenwick · Post by **jrenwick** » Thu Aug 04, 2005 8:15 pm

I think I would want to understand why a safetied nut and bolt became loose before I flew the airplane again. The tailwheel on my J3 used to loosen up over time, and I retightened the main bolt that holds it a couple of times before I discovered that it was crushing the tubing inside the fuselage. (I had the fuselage structure rebuilt with a bigger tube with a bushing inside it, and I believe that's fixed now.)

Rudy, if your bolt is stretching, how long before it fails?

Best Regards,

John

Post by **GAHorn** » Fri Aug 05, 2005 12:04 am

Rudy, isn't this the same sort of problem we diagnosed at the Wilmington Convention? Seems I recall Ol' Gar and I taxiing your airplane around because of your complaint that the airplane sometimes simply took a turn, and we discovered your tailwheel leafspring stack was twisting/sliding due to loose bolts and a loose tailwheel assy.

N170CT · Post by **N170CT** » Fri Aug 05, 2005 4:00 pm

Rudy,

FWIW, I had a similar situation with my 170 in that the airplane would swerve uncontollably to the left. Departed the runway (always left) three times before I sorted out the problem. In this case, the left Outboard MLG bracket (the large bracket the flat spring passes through) had exfoliated and allowed the left main leg to shift aft which apparently caused the aircraft to go left. This was difficult to detect by inspection and required a good flashlight and a mirror through the hole in the floor. Replaced the bracket with one from P-Ponk which was a difficult

but perfect fit. No problem since. Sooo, you might want to take a look at that. Chuck

rudymantel · Post by **rudymantel** » Sat Aug 06, 2005 9:01 am

Yes, this was a similar problem to the one in Wilmington which George and Gary (Ol'Gar) diagnosed. I don't recall the springs being loose but the tailwheel casting was loose where it bolted to the main spring, same as this time. Gary tightened it and it made a huge improvement.
A few weeks later it again was loose and I replaced the bolt and nut with a castillated nut secured with a cotter pin. No more problems till the other day, when I found that the locked nut had come slightly loose, which is worrying.
I tightened the nut and yesterday flew a trip with three landings, all of which felt normal. But I will look into it further. Something must be wearing- I'll replace that AN7 bolt in any event.
George, that eyebolt you ordered- P/N 0642105, does it have a hole for a cotter pin ?
Rudy

rudymantel · Post by **rudymantel** » Sat Aug 06, 2005 9:03 am

Chuck, I don't think my problem is main-gear related. I'm sure it's a tailwheel issue-
Rudy

johneeb · Post by **johneeb** » Sat Aug 06, 2005 11:50 am

Rudy,
Check and see if yu are missing the spacer (IPC page 155, part number 0442011-3) between the main spring and the Bracket Assembly. If it were missing the movement between the spring and the Bracket assembly would over time loosen the bolt.

rudymantel · Post by **rudymantel** » Sat Aug 06, 2005 2:31 pm

Thanks Joneb- I'll certainly check for that spacer-
Rudy

Joe Moilanen · Post by **Joe Moilanen** » Sun Aug 07, 2005 6:43 am

I've had to tighten the bolt on mine periodically also. I made a spacer the last time that I replaced my mainspring and I'm sure that it is needed but i's still bugging me.

Joe 4518C

Post by **GAHorn** » Sun Aug 07, 2005 10:14 pm

rudymantel wrote:Yes, this was a similar problem to the one in Wilmington which George and Gary (Ol'Gar) diagnosed. I don't recall the springs being loose but the tailwheel casting was loose where it bolted to the main spring, same as this time. Gary tightened it and it made a huge improvement.
A few weeks later it again was loose and I replaced the bolt and nut with a castillated nut secured with a cotter pin. No more problems till the other day, when I found that the locked nut had come slightly loose, which is worrying.
I tightened the nut and yesterday flew a trip with three landings, all of which felt normal. But I will look into it further. Something must be wearing- I'll replace that AN7 bolt in any event.
George, that eyebolt you ordered- P/N 0642105, does it have a hole for a cotter pin ?
Rudy

Rudy, the IPC specifies a friction lock nut (AN 365-720) for this installation, and both the original bolt (AN 7-20A) and the L-19 PN 0642105 are undrilled. Mine has never loosened.

rudymantel · Post by **rudymantel** » Mon Aug 08, 2005 3:40 pm

This is getting curiouser and curiouser- My leaf springs are 1.5 inches wide and the inside channel of my Scott bracket casting is 1.75 inches wide. There is a wide, shallow, u-channel spacer that fits in the bracket and over the spring to adapt the wide bracket to the narrower leaf spirng.

There is no Lug (0433132) No. 1 on the IPC page 154 illustration.
(Hill Aircraft call this a Tab - $38.64) What is it for and where does it fit ? Does it somehow relieve the stree concentration on the spring?

There also is no Spacer (0442011-3) No.4 on IPC drawing, mentionet by Johneb. Univair's price for this Scott part is $78.08. How does this work ? Would it fit with my wide bracket and narrow leaf spring ? Is that the problem- do I need an entirely different tail wheel that better fits the spring?

Rudy

JTS · Post by **JTS** » Mon Aug 08, 2005 4:51 pm

Hey Rudy. To start, I believe the lug (No.1 in drawing) is actually one of the two tabs that attach the springs and chains to the rudder bellcrank(refer to page 28 No.14 in IPC). Secondly, the spacer mentioned by Johneb(No.4 in drawing) is probably the u-channel spacer that you described earlier that fits between the spring and tailwheel casting.
You might want to try some thin sheet metal to shim between the casting and spacer, the spacer and spring, or both. Hope this helps!
Jody

N2865C · Post by **N2865C** » Mon Aug 08, 2005 6:07 pm

JTS wrote:Hey Rudy. To start, I believe the lug (No.1 in drawing) is actually one of the two tabs that attach the springs and chains to the rudder bellcrank(refer to page 28 No.14 in IPC).

I think Jody is right. The tabs are not used with the Scott 3200 installation. Scott calls for eye-bolts instead of the tabs. The Scott uses a spacer for the narrower springs. Last time I looked, that little spacer was about $100.00 (ouch). I have a copy of the Scott installation instructions for the 170 I can fax you if you need it.
jc