REFLECTOR: Unexpected door opening

Brian Michalk michalk at awpi.com
Sun Jun 7 11:24:01 CDT 2009


One comment:

I had a very difficult pilot side door.  The alignment was never quite
right, and I thought it would come into fitment after enough time to
relax.  Well, ten years, and it was still tight to require considerable
force to fully extend the pins.

I took a reamer with the thought that I would ream out the tube and
re-pot a new tube in place.  What happened is that the old tube got hot,
and became unbonded from the epoxy and spun in the hole, then I could
remove the tube.  Next, I reamed out the area and repotted a new tube
with the door closed and pins extended.  It was very easy to do.  Less
than an hour of work.  If the receiver tubes were not round this would
have been a bit of work.

I've found the factory design to be pretty good in general.  I guess we
each have out little issues.  Mine was with the door springs and the
copilot latch.

I do think maybe the hinges could be a little weaker.  Maybe two screws
rather than the four called in the manual.  This is for the door opening
problem.

Jim Agnew wrote:
> *Hi* Scott Baker,
> 
>  
> 
> I agree that the possibility of all 4 areas failing of the fiber-glassed
> in tubes is unlikely (things do change when one or more of the latches
> are not enguaged), However almost the entire outboard load is taken up
> by a small round section of the tube pushing on the interior of the
> fuselage.  The attached "Door Latch Socket picture" shows my stainless
> steel T shaped answer that has a large flat section to spread the load
> over a larger section of the fuselage and to prevent the rolling
> tendency of the round tube.  If you look closely you will see that the
> top side holes are slightly tapered to allow easier pin entry into the
> close fitting hole.
> 
>  
> 
> Jim
> 
> 
> 
>  
> 
> James F. Agnew
> 
> Jim_Agnew_2 at Yahoo.Com <mailto:Jim_Agnew_2 at Yahoo.Com>
> 
> Tampa, FL
> 
> Velocity 173 Elite Aircraft Completed & Flying
> 
> 
> 
>     ------------------------------------------------------------------------
> 
>     *From:* reflector-bounces at tvbf.org
>     [mailto:reflector-bounces at tvbf.org] *On Behalf Of *Scott Baker
>     *Sent:* Monday, July 20, 2009 7:00 PM
>     *To:* Jim Agnew ; Velocity Aircraft Owners and Builders list
>     *Subject:* Re: REFLECTOR: Unexpected door opening
> 
>      
> 
>     I think the liklihood of four (4) areas of failed fiberglass in the
>     receiver areas is slim to none.
> 
>     Not engaging the pins into the receiver - likely if the door handle
>     is not rotated to its fully closed position.  Definately a
>     possibility if there is no micro switch and warning light to tell
>     the pilot that the pins are not fully engaged.
> 
>     Good point on the possible problem of using wooden dowels as a "pin
>     extension".  If the dowels were to become stuck in the tube and
>     remain in contact with the micro switch, it would cause a false
>     "door locked" indication (absence of a door ajar warning); however I
>     would hope that we would recognize this situation following start
>     and taxi (meaning we want to verify the door ajar warning should be
>     ON with the door open).
> 
>     SB
> 
>         ----- Original Message -----
> 
>         *From:* Jim Agnew <mailto:jim_agnew_2 at yahoo.com>
> 
>         *To:* Velocity Aircraft Owners and Builders list
>         <mailto:reflector at tvbf.org>
> 
>         *Sent:* Friday, June 05, 2009 5:39 PM
> 
>         *Subject:* Re: REFLECTOR: Unexpected door opening
> 
>          
> 
>         Al,
> 
>          
> 
>         There are several failure modes for the door latches.  First the
>         tubes that accept the latch pins could fail I.E., part from the
>         fiberglass.  Second the latch pins may not be deep enough into
>         the tubes so the stress is on the flat portion and not the
>         tapered part that will try to push itself out. Third the latch
>         pin can unscrew from the push rod (I know one of mine did even
>         with locktite on the threads, I now use RED Locktite on them). 
> 
>          
> 
>         I have auto locking so closing the latches automatically locks
>         them and you must pull up on the door lock before you can move
>         the handle.
> 
>          
> 
>         As far as the door warning switches go I only have one in the
>         forward center pin location with a nylon mushroom button that
>         activates a roller micro switch.  I know a lot are in the bottom
>         tubes with wood rods that can swell from water and in the
>         perfect place to collect dirt that can jam them. 
> 
>          
> 
>         Just food for thought.
> 
>          
> 
>         JIm
>          
> 
>         James F. Agnew
> 
>         Jim_Agnew_2 at Yahoo.Com <mailto:Jim_Agnew_2 at Yahoo.Com>
> 
>         Tampa, FL
> 
>         Velocity 173 Elite Aircraft Completed & Flying
> 
>          
> 
>          
> 
>         ------------------------------------------------------------------------
> 
>         *From:* Al Gietzen <ALVentures at cox.net>
>         *To:* Velocity Aircraft Owners and Builders list
>         <reflector at tvbf.org>
>         *Sent:* Friday, June 5, 2009 1:48:33 PM
>         *Subject:* Re: REFLECTOR: Unexpected door opening
> 
>         And for those who at the end of your personal deliberations who
>         would still opt for the gull wing, would something as simple as
>         a deadbolt (weighing only a few ounces) serve as a fail-safe
>         back-up to the traditional lock assembly?  Thanks for your thoughts.
> 
>          Robin
> 
>         Robin;
> 
>          
> 
>         My thought is that we essentially have 4 ‘deadbolts’ in the
>         current configuration.  We simply need a ‘dead sure’ way of
>         knowing they are in place.
> 
>          
> 
>         My further observation is (added to by my experience flying home
>         with a temporary door) that net outward forces on the door in
>         flight are relatively small – at least compared to the strength
>         of the four latches. I think there is likely some negative
>         (outward) pressure over much of the door, likely stronger toward
>         the front edge, and some positive (inward) pressure in the area
>         of the strake extension, and its junction.
> 
>          
> 
>         I have no idea if there are forces due to small distortion of
>         the fuselage during flight that may work to move the latch pins
>         out of the tubes, but it is not impossible.
> 
>          
> 
>         FWIW,
> 
>          
> 
>         Al
> 
>         ------------------------------------------------------------------------
> 
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> 
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> 
>  
> 
> James F. Agnew
> 
> Jim_Agnew_2 at Yahoo.Com <mailto:Jim_Agnew_2 at Yahoo.Com>
> 
> Tampa, FL
> 
> Velocity 173 Elite Aircraft Completed & Flying
> 
> 
> ------------------------------------------------------------------------
> 
> 
> ------------------------------------------------------------------------
> 
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