Mailing List lml@lancaironline.net Message #55655
From: <Sky2high@aol.com>
Sender: <marv@lancaironline.net>
Subject: Re: [LML] Re: Close Tolerance Bolts
Date: Sat, 10 Jul 2010 21:01:12 -0400
To: <lml@lancaironline.net>
Grayhawk was not thinking much......  The Landing Gear system uses bolts as pivots and bearings... The push rod systems tightly lock down bearings with torqued up bolts -- the slop might be in the bearings, but not in the bolts.  Oh well.........
 
The worst landing gear offender is the nose gear tab to over-center link.  I once removed the bolt when the nose gear was loose and noted that it looked like a cam since it was worn at the thread area just before the bolt shoulder.  Randy Snarr had a nice replacement for that last link with an embedded bearing just slightly wider than the link itself - thus it could be bolted up tight and still pivot on the bearing - end of nose gear looseness problem.
 
Grayhawk
 
In a message dated 7/8/2010 5:47:44 P.M. Central Daylight Time, Sky2high@aol.com writes:
Bill,
 
Great information.  Considering the number of linkages in the elevator and aileron push rod systems, perhaps such bolts would reduce the lash there also.
 
Grayhawk
 
In a message dated 7/8/2010 5:25:48 A.M. Central Daylight Time, lancair403@verizon.net writes:
Since building my 320, I'd noticed the free-play in the main gear while on the jackstand. Not an excessive amount, but enough to bother me. Most of it originated at the lower gear leg attachment, but there was also some at the overcenter link attachment to the gear leg. I decided to see if that free-play would be appreciably reduced by the use of close tolerance bolts - it was. They eliminated about 80% of the free-play at each lower gear leg attachment and almost 100% at the overcenter link attachment (there was also a slight amount in the rod end bearing itself. I wasn't impressed with the quality of the one supplied with the kit and replaced it with a Heim HME-6 which had virtually no free-play). I also installed close tolerance bolts at the upper and lower shock attachments and at the overcenter link pivot.
I had almost no free play at the nose gear overcenter link attachment, but installed a close tolerance bolt there also and it only improved the condition.
Aircraft Spruce does not stock many close tolerance bolts, I purchased mine from Genuine Aircraft Hardware, which has all sizes and lengths. I think they are a great thing and might install them throughout the airframe in the future.
 
Bill Rumburg
N403WR (Sonic bOOm)
 
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