REFLECTOR: Main gear not locking on dump

[Laurence Coen]

Phil,

First, my cylinder works fine and is 18 years old.  I did actually inadvertently create the condition that you describe. My plane was complete and flying with no gear problems.  However if I rocked the wings on the ground the gear made a creaking sound.  Us old folks don't like creaking joints so I set out to fix the "problem".  I started adding shims between the gear leg outboard  tops and the sockets to get rid of play.  I reached a point where the gear went down on power but wouldn't lock with manual dump. Sound familiar?  It turns out that the combination of normal cylinder friction and too good a fit on the sockets can be a bad thing.  By the way, I eliminated the creaking sound by applying Lubriplate to the gear tops.

Larry Coen
N136LC


From: Phil Hooper 
Sent: Wednesday, July 31, 2013 10:36 PM
To: Velocity Aircraft Owners and Builders list 
Subject: REFLECTOR: Main gear not locking on dump


Dear collective, slow building Hooper here.  

I have a bit of a challenge with the main gear.  Everything works fine, full lock when hydraulic-driven.  When we test the dump valve release, the gear goes down, but stops just short of lock.  Scott Swing thought it might be a weak spring and sent me the strongest he had...same problem.  There is no drag whatsover on the main gear bolt, nor in the gear pocket sleeves.  It all moves freely and will lock every time when hand dropped slowly from both sides, but with no cables attached.  There is also plenty of slack in the cables when using hydraulics, probably too much at this point.  

We have found that by giving a manual nudge, pulling the ram out about another 1/2" out, bam, it locks.  So the problem points to the ram having resistance to coming out to the end of it's travel as the weight of the gear pulls the cables, and thus the ram. 


Scott speculated that the ram might loosen up with time, but so far, it shows no signs of yielding.  I wonder if the seals are too old (about 11 years) and if the cylinder should be rebuilt...ugh, just when we got all the leaks cleared and cleaned up the last of the spilled fluid.


I wonder if any of you fine folks have had a similar problem and how you solved it.  One interesting thing we tested was adding two and half pounds of weight to the center of the mechanism...presto, down it came, and locked.  I have also thought about adding a downward pulling spring without 5 pounds of force, or an emergency cable connection that would pull the overcenter down into lock (parts to break).  The easiest solution may be g-forces if I'm ever alone and it won't lock, but I don't know if I can trust that.


What say you, and thanks to any and all with wisdom superior to mine.  Blessings to all.  

Phil


-- 

-- 
Phil Hooper
President
Harvest Development & Media Inc.
19851 Yorba Linda Blvd., Suite 204
Yorba Linda, CA 92886 
voice: 714.693.8745
fax: 714.777.0134
web: http://www.hdmnet.com/
email: phil at hdmnet.com





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