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Shane, we have bonded in bushings, pieces of
aluminum plate, etc. It just depends on the thickness of what you are starting
with and how you trimmed out the back side of the door frame. You are limited by
the thread depth on the ball stud. I can tell you that just floxing up the hole
won't last, though...
If you have the depth to put an area washer on the
stud, that would be good...
Brad Simmons Airframes Inc. 39 Airport Rd. Milan, TN
38358 731-686-3610 731-686-3613 fax www.airframesinc.com
----- Original Message -----
Sent: Tuesday, October 08, 2013 11:22
AM
Subject: [LML] Re: Cabin door strut on IV
series
Brad,
the stud on my door looks to be a bit loose. Is there an easy fix before
it completely fails?
Shane
89GG
From: Lancair Mailing
List [mailto:lml@lancaironline.net] On Behalf Of Brad
Simmons
Sent: Tuesday, October 08, 2013 8:42 AM
To: lml@lancaironline.net
Subject:
[LML] Re: Cabin door strut on IV series
I could not view
your YouTube video; it asked for a log in...
Door strut damage
is becoming a common item as the fleet ages. We are seeing problems on
probably a 3rd of the planes that we service. There have also been at least a
couple of cracked windows possibly attributed to the door strut stress placed
on the door.
Assuming your ball
and socket alignment isn't so bad that the range or motion is exceeded, the
other common issue is the stud wallowing out the hole through the carbon
frame. Once it begins to move around, the threads will quickly open up the
hole diameter, and as the assembly becomes loose, the socket will either pop
off, or damage the fingers in the socket.
There's more than
one kind of ball and socket floating around out there, also. Some don't have
the same amount of motion as others, so if your replacement strut did not come
from Lancair, make sure that the similar ends will actually allow the
needed rotation.
Adding a strap to
the door to allow you to cushion the opening is a good idea also. I still see
folks that land, unlatch the door and just push it up and allow it to open on
it's own (and you know who you are!!!). I can just about guarantee you that
the ball studs will be loose in their composite
mounts.
Brad Simmons
Airframes Inc.
39 Airport Rd.
Milan,
TN 38358
731-686-3610
731-686-3613 fax
www.airframesinc.com
----- Original
Message -----
Sent: Tuesday, October
08, 2013 6:55 AM
Subject: [LML] Cabin door
strut on IV series
I have to say that my first attendance to a LOBO fly in
was awesome ( to use my children's and their children's cliche). The
chance to meet so many enthusiastic, knowledgeable and fun Lancair folks
provided WAY more benefit than I ever would have imagined. Thank you
to the board, the vendors, presenters and to everyone involved. I
loved it and so did my wife, Anne.
I saw some folks examining a IVP door strut on Saturday I
think. The attachment at the frame was very loose so that the ball
stud was flopping around. Close inspection showed that the door frame
was cracked under the stud. I'm not sure whose plane this was but I
think it is the one that vibration measurement equipment had recently been
attached to for studies.
The door strut triggered memories of similar
occurrence with my strut a couple of years ago prior to first flight.
I would guess the smart folks who noticed this also figured out the
reason for the failure, but just in case I will share what I found and how I
dealt with it.
The problem with the door strut is that the arc described
by the strut during opening and closing exceeds the range of motion built
into the ball stud socket on the lower end of the strut. Therefore the
door frame is wrenched back and forth during door operation when the stud is
attached to the door frame without modification to the frame. There is
a plane you can find by experimentation or by mathematical exercise if you
are so gifted and inclined to pursue (I am not) that will allow the socket
to move within the design limits and therefore not stress the stud and the
door frame. Once this plane is determined, you can use a small washer
of wood, foam or other material to shape the door frame where the stud
penetrates the frame. You'll need to cut out a bit of the frame to
accomplish this. since my frame was broken here it made that part
simple. Super glue or hot glue can hold the form in place. Then
lay up two BID of carbon fibre cloth over the form and remove the form
material when done. Lay up several layers on the back side to
strengthen the mod and to secure it by sandwiching on both sides of
remaining frame.
It gets a little more complicated because the
back side in my case was in very tight quarters. When complete I found that
the screw stud on the ball stud part was too short. I was able to go
online and find a replacement at very nominal cost and that had plenty of
thread length for the purpose.
I have uploaded a video to YouTube of the way the
attachment looks now. See link below. I hope it helps
someone.
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