REFLECTOR: main gear pivot bolts

[Hal Smith]

Dave,  Could you send me some pictures?  I am building an XLRG and have not 
installed the landing gear yet.  Probably good to beef up when installing 
rather than later.

Hal Smith
5305 169th Pl SW
Lynnwood, Washington 98037

Thanks,
Hal
----- Original Message ----- 
From: <davedent at comcast.net>
To: "Velocity Aircraft Owners and Builders list" <reflector at tvbf.org>
Sent: Friday, February 09, 2007 11:51 AM
Subject: Re: REFLECTOR: main gear pivot bolts


> FYI
> I have gone through at least three of the 5/8" bolts on my right gear of 
> my XL/RG.  The first one was a grade five and the last two wear grade 
> eights.  They all got bent.  So I have spent a lot of time trying to find 
> out why.
>
> Finally I found out that the moment on the pivot point was way to long. So 
> I built and added a plate to the fwd main gear bulkhead.  Much like the 
> one on the nose gear pivot but a 3X4" plate with inbeded bushings.  This 
> plate is sandwiched on the  bulkhead with four #10 bolts and flox to even 
> off the surfaces.  If anyone wants pictures, send me you address and I'll 
> send it. I can't put them in these emails.  I tried the picture of the new 
> Vesta prop and it wouldn't go through. By the way the prop weighs in at 
> 67lb with spinner.
>
> I also made new captivators out of eight plys of carbon and added a web to 
> the fwd side of the captivator to beef up the fwd torsional loading that 
> is applied on each landing.
>
> I found out that I had a tire that had got out of balance and caused the 
> gear to vibrate so much that it bent the bolt and wiped out the fwd main 
> gear bulkhead bushing. Actually tore the bushing out of the bulkhead. It's 
> just floxed in remember. This is the gear I completely covered with all 
> cabon instead of the uni E-glass. It ended up way to stiff. So doing 
> transferred all the loads to the bolt and pivot points. Lesson learned 
> here as well.
>
> The next one got taken out because the brake line to that gear had a 
> slight kink in it, because of being removed and not noticing it.  This 
> caused the brake not to release fast enough causing the gear to take a 
> beating again.  So doing bending the bolt again.  On just one landing it 
> took out the brake pads and the bolt.  So make sure the brake lines, 
> NylaFlow type, are in so that no kinks can happen.  Something simple like 
> that can get you, BAD.
>
> Related to the bending of the bolts, if you haven't checked lately, I 
> would do a rotational check on your bolts.  If you can't rotate them by 
> taking a 15/16th wrench and rotating it at the head of it, it is bent.  If 
> it is bent just a little and I mean just a little it can cause the whole 
> alignment to be off.  So doing can prevent proper travel and failure to 
> have it come up in the well right and hang up in the well.  Believe me, it 
> don't take much. I have seen some wells that if you just change a tire, it 
> wouldn't fit up in the well.  Now add this miss alignment to it and you 
> can see what can happen.
>
> One one occasion on the way home from OSH, last summer, it got bent just 
> enough so the gear linkage went up about one inch higher, it don't take 
> much remember. During the next retract it caught on the overhead vent 
> drain line and prevented the gear from going all the way into the lock 
> position. The drain line actually caught in the notch in the overcenter 
> link. This allowed the gear to become unlocked and pulled the one gear 
> back up into the well, so doing the plane came to a stop with two legs 
> down and one leg up.  A real bad day.
>
> This bent bolt was caused by a hard landing the flight before this onto an 
> major down hill short runway by my partner.  No fault of his, just not 
> prepared for such a runway.  The bolt should have been able to take it. 
> This was the grade five bolt also. I'm sure if it had been the grade eight 
> it would torn out the fwd bulkhead bushing as well.  It is only floxed in 
> as you know and with that long moment arm you can see what it could do. 
> That's why I did the extra beefing up in that area. By adding the plates 
> and shear web on the captivator.
>
> I know I have gone on a long time on this subject but I think you all 
> should know what I have found and did.  Learn from others, and don't think 
> it won't happen to you.  IT WILL>
>
> By the way I buy my grade eight bolts from Fastinal.  They are all 
> cirtified and will give you papers if you ask for it a head of time.
> Dave
>
>
>
> -------------- Original message ----------------------
> From: Scott Derrick <scott at tnstaafl.net>
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