Mailing List lml@lancaironline.net Message #50977
From: PAUL HERSHORIN <paulhershorin@bellsouth.net>
Sender: <marv@lancaironline.net>
Subject: Re: [LML] Re: LNC2 Aileron bellcrank bearing failure
Date: Thu, 09 Apr 2009 20:24:41 -0400
To: <lml@lancaironline.net>
Thanks for your reply--I took it apart today and found that the baring was rotating within the holder--I had extra barings and replaced the old with new--I bucked the rivets in and put everything back together--things are tight now and I will be very careful to check for any play on all walk around inspections--if I have someone with me I will have them hold the stick still--I will move the ailerions for any play--if there is any play I will tear into the problem again.  Thanks for your support.
Paul


From: "Sky2high@aol.com" <Sky2high@aol.com>
To: lml@lancaironline.net
Sent: Thursday, April 9, 2009 1:01:22 PM
Subject: [LML] Re: LNC2 Aileron bellcrank bearing failure

Paul,
 
From your description I'm not quite sure where the failure is located.  If I remember correctly, the bell crank bearings are captured between riveted plates and meant to rotate in one plane only.  Any deflection from that plane is handled by the rod end bearings bolted up to the bell crank and protected by area washers to ensure the capture of the rod ends. 
 
Typically the bell rank bearing housing rivets are squeezed rather than bucked - squeezed rivets can be more fragile than bucked rivets in that they don't fill the hole as well.  
 
Were I you, I would remove and inspect the bell crank for work hardened and possibly sheared rivets since vibration is a common cause of fastener failure.  Perhaps even replace the rivets in both the left and right bell cranks (assuming the bearings are not damaged).  The method used by Lancair is not unique to them - If you can find a better way, do it.  That is the beauty of the experimental, amateur built certification category.
 
Scott Krueger
 
PS 1100 hours and no such problems.  Uh, my annual condition inspection is due this month and I will look at these bearing more closely.
 
 
 
In a message dated 4/9/2009 6:49:57 A.M. Central Daylight Time, marv@lancair.net writes:
Posted for PAUL HERSHORIN <paulhershorin@bellsouth.net>:

 I was returning on a flight the other day and the stick started to vibrate--I
looked out at the aileron and I could see the left aileron fluttering--I
landed without any problem and started my investigation into the problem. 
Upon opening up the bellcrank cover and moving the aileron the bellcrank was
pushing up and down when moving the aileron and holding the
stick stationery.   The bearing was twisting---my question is how have other
individuals corrected this problem--the way it is designed is an accident
waiting to happen.
 Paul Hershorin
 360--471LA 

--

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