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Hello Scott & LML Group,
(Scott, I'm posting this to the LML so it will
become public knowledge - hope you don't mind.)
Welcome to the wonderful world of Lancair IV-P
steps! <grin> Of all the things we had to figure out, the step
was probably one of the worst and if the truth were told, we were pretty
lucky with our installation!
Our step installation was pretty much according to
the Lancair drawings that came with the kit. Some comments about our
installation:
- Make access panels both top and bottom so you can
work on the damn thing! You "will" work on it, don't worry!
- Don't locate the step mechanism too far back in
the wing root fairing. Space gets tighter the further you go back.
- Position the bottom of the step as close to the
rear spar as you can. (refer to comment # 2)
- Don't try to get the cable that pulls the step up
too tight - it will break or pull the ball out of the end of the cable.
Just tight enough to get the step up into the cavity.
- Per Charlie, grind clearance on the gearbox where
the clamp goes around the gear leg so the possibility of jamming is
eliminated. I'm talking about the bolt on the clamp - if it ever slips
around, it could bind the gear where the bolt may hit the gearbox. It
takes quite a bit of grinding to get enough clearance.
- Spend some time shaping the guide tube for the
cable. You want it to "guide" the cable - not force it! After you
get everything painted or just before you fly, lubricate inside the tube to
reduce friction. I used a grease gun to "flood" the tube with
grease. Watch the clearance between the guide tube and the flap
rod! Check it going up and down.
- Generously lubricate all the rollers, guides and
latch mechanism.
- I polished the ends of the latch mechanism to
reduce friction (also well lubricated)
After we did all of the above, the step would only
come down at about 100-110 kts. When we jacked the airplane and cycled the
gear, everything worked as advertised. Anything faster than 110 kts, the
step would hang up on the gear (the gear got ahead of the step). When on
jacks, the step would extend first, but never would latch into position - even
after all of the polishing and lubrication.
Our "evaluation" of the step issue was that the
spring was not strong enough. I had several springs made during our
testing phase and we finally settled on a spring that was .100" diameter
(compared to .072" original diameter). According to the spring shop, this
made the spring at least 2 times as strong as the original. With the new
spring, the step would extend and lock into position with speeds up to 155 knots
(I haven't tested any faster). When we tested the spring with the airplane
on jacks, the step would extend and lock into position.
The company that manufactured the springs is Custom
Made Springs, in Norfolk, VA. The owner of the company is Lou
Schmidt. The springs are identified as "Ed Smith's airplane
step spring". Very creative - huh?? Lou's phone number
is: 757-489-8202.
The charge for these springs has been $40.00 each -
not too bad, considering it is a custom made spring and each one is
hand-made. I recently ordered some for some other fellows on the LML and
shipped them out via Priority Mail. I did have a couple of extras made, so
if you want one, I'll be glad to sell you one of the extra ones. The
Priority Mail charge is $4.95. I don't think any of the fellows I sent the
springs to have tried them - they are like you - in the building process, so
there aren't any statistics - except for me. Sorry. If you want to
contact Lou direct, please feel free to do so. This is not a money-maker
for Ed Smith - just a service to the LML group.
You do have to drill the hole that the spring tang
fits into to at least .100". I would keep the fit as tight as
possible. I drilled mine to .125" and I had the tang slip out once - no
explanation. I reinstalled the tang and it hasn't slipped out since.
I did bend the tang a little to "tighten it up in the hole".
When Lou made the springs, I did have him wrap the
end that goes around the step leg into almost a complete circle. The
original spring (end on step leg) use to hang up on the opening in our wing
fairing, but with the end modified, I haven't had that problem. You will
have to cut the end of the spring so you can get it over the step leg.
Just leave as much as you can and still get it to go over the leg.
Another theory about our step problem was that
the boundary layer of air under the wing was helping hold the step up in the
wing. We never pursued that theory, but at Sun-N-Fun this year, I talked
to the owner of a IV-PT that had riveted a "tab" along the step foot that stuck
out in the airstream when the step was retracted. The owner told me that
since he had riveted the tab in place, the step had come down every time!
It appeared to extend beyond the step foot about a half inch.
Maybe someone will chime in on this modification that has "been there - done
that". That does add some validity to our "boundary layer
theory".
If anyone has any questions, please feel free to
give me a call (757-641-2387) or email @ 2luv2fly@cox.net.
Tailwinds,
Ed Smith
----- Original Message -----
Sent: Wednesday, October 14, 2009 8:35
AM
Subject: Lancair Question
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Ed;
I am currently in the process of building a IV-P and am working on
the retractable step. Charlie Kohler suggested I get in touch with
you about some changes you made. I searched the LML archives and
saw the posting where you described changing the spring. Two
questions:
1. Is that pretty much the extent of the changes you made to
the step, or were there others?
2. Could you put me in touch with the company that built your
new spring, or get me one, or whatever?
I certainly appreciate any help you can provide.
Thanks!
Scott Seagrave
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