From: N295VV@aol.com
Message-ID: <0.4c20c8de.2543679c@aol.com>
Date: Sat, 23 Oct 1999 15:33:48 EDT
Subject: LNC4 Flap Actuator Cylinder HC-09
To: lancair.list@olsusa.com
Mime-Version: 1.0

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From: n295v v @aol.com

Listen up LNC4 builders and flyers.  If your plane is flying, it is time to 
open up your gear box lid and look at your travel on the Flap Actuator 
Cylinder HC-09.

Bill Maddox and I have had the wonderful thrill of watching the 1/4" walls  
of the gear box flex in and out like the walls of a cracker jack box being 
moved by the fist of a six year old.

It is not a pleasant sight.

The simple fact of the matter is that the cylinder has a throw that is about 
3/8" too long for the arc throw of the Flap Bell Crank.  That is 3/8" under 
the best circumstances, and more under the worst circumstances.  

As I mentioned in my previous posting, the 1200 psi that is moving the walls 
of the gear box in and out is fully capable of decapitating the Flap Bell 
Crank, the Flap Push Rods, the Fowler Track, or the attachment of the Fowler 
Track to the Spar.

Under the most ideal conditions, the throw might be within satisfactory 
limits, but since the wings are constructed separately from the fuselage and 
gear box installation, the holes in the fuselage and the adjustments of the 
bell cranks in the wings make the ideal condition almost impossible to attain.

Remove the 1/4" bolt from the Flap Bell Crank, and cycle the cylinder in both 
directions to determine if your throw is longer than the swing.  Or, if you 
want something to give you nightmares for a week, don't disconnect the bolt, 
cycle the cylinder, and watch your gear box to see if it huffs and puffs like 
the bellows of an aneroid barometer.

There is a cure.  Order an EL-6B Elevator Control Plug from the factory, 
disassemble the cylinder, and put it in one end to limit the stroke of the 
cylinder rod travel.  While you are at it, ask them to notify owners that 
this is a problem in some planes.  The plug is 3/4" as shipped, and you may 
want to put it in a lathe and shorten it to 1/2" or so, as the larger length 
will reduce the angle of the extended flaps quite a bit.

As a matter of interest, please let me know by email if you find a problem 
with your plane (or if you don't find a problem as well).  I have spent a 
total of 40 hours or so examining this, and I would like some confirmation.  
I know of 3 such cases so far.

David Jones, Pecatonica, Illinois


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