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<< Lancair Builders' Mail List >>
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In a message dated 11/8/00 2:04:09 AM EST, Matt Hapgood writes:
<< 1. The air strut. I thought - maybe the air strut is too old (8.5 years)
and needs to be replaced. I tried to disconnect it. No such luck. This is
a two- person job, requiring removal of the bracket first.>>
No. Disconnect the drag link from the nose gear strut. The air strut will
then fully extend and be removable by yourself. If you can measure how much
force it takes to compress the strut when attached to the drag link (tire
jack sitting on bathroom scale?) then you can use trigonometry to figure out
the force required to compress the air strut.
<>
Oh. Now I see. Maybe a long wrench on the nut, let it wedge against the
tunnel side, use duct tape to hold it there while you turn the other side?
For a longer term solution, I installed nutplates on my air strut brackets.
Much easier to pin the strut thru the brackets first and then bolt to the
firewall. Plus you can do it yourself.
<< 2. The hydraulic strut - I noticed during this process (actually, while
trying to reconnect the air strut) that the hydraulic ram extends about
3/16" beyond where the gear overcenter stops the strut. This means the
hydraulic cylinder is pushing on the overcenter link - very hard. I went
through the archives and read some stories about delaminated nose gear
tunnels and adjustment of this cylinder.>>
Listen to Ric on this one. It WILL trash the nose gear tunnel top. Make
sure the cylinder is fully extended UNDER PRESSURE and set the rod end
bearing so that you can just drop a bolt through and connect the cylinder to
the drag link.
<< SO - do I need to make it so it is
just barely pressing on the overcenter link when extended? Specifically -
should I extend the gear with the pump, then while under pressure, set the
rod-end length to the extended overcenter length?>>
Yup. That's how it's done. Check your main gear, too.
<< Part of the problem with this is that the cylinder appears to be too long.
It will require that I grind off some of the threaded end of the bearing.
As it is currently configured, the rod-end bearing, check nut and aluminum
"stop" are all sandwiched together. Something would need to go - the check
nut should stay, and there is no additional material that could be filed off
the aluminum "stop". So that leaves the rod-end bearing.>>
You might want to make new aluminum brackets before you hack away at your
hydraulic cylinder. That way if you ever need a new cylinder you don't have
to fix that one, too. Use the same attach holes (bracket-to-tunnel) and
locate the bracket-to-cylinder holes further aft. You might choose to
anodize these new brackets, but nobody can see them unless they're lying on
their back on the ground, which only a Lancair nut would do (but then, who
else would you want to impress?)
BY THE WAY, and this is important, make sure that when the gear is retracted
the cylinder bottoms out on the aluminum stop. You don't want to be pushing
on the nose gear tunnel with hydraulic pressure (except when the gear is in
transit, of course) or you WILL delaminate the tunnel. I think this is more
a problem on extension than retraction, however.
<<3. When I reassembled all the parts, I noticed part of the "free-fall"
problem - friction. The air strut rod end does not have a bearing. When I
snugged up the bolt holding it to the gear arm, it didn't want to freely
rotate. So I loosened the nut one notch on the castle - seemed to help.>>
Make sure that you don't have friction where the nose gear strut pivots in
the engine mount. If the spacer sleeve between the two square blocks is too
short, there will be friction keeping the gear from falling down. Test for
this by removing the drag link and verifying that the strut can freely swing
back and forth (like a pendulum). A new sleeve is about $4. I know, I had
this problem too.
<<So I have it loose enough to move
freely, but no slop. I hope this is okay.>>
I assume you have a castle nut with a cotter pin on all these "rotating
bolts"....
- Rob Wolf
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LML website: http://www.olsusa.com/Users/Mkaye/maillist.html
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Please send your photos and drawings to marvkaye@olsusa.com.
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