LS-6a Landing Gear Problem

[Michael Higgins]

My LS-6 gear collapsed and now will not lock down or
up. Has any other LS-6 drivers had this happen? What's
the fix?

I had the glider on the trailer cradle for assembly
and lowered the gear. I think the cradle was a little
too low and the gear contacted the ground prior to
the mechanism locking fully down. I didn't know that
it wasn't locked and pushed the handle to the locked
position. The gas strut retracted and allowed the
handle to lock down, without the gear being actually
locked. When I pushed the glider off the cradle, the
gear collapsed. When collapsed on the ground, the handle
was still in the locked-down position.

With plenty of help, I put the glider back on the cradle
and then tried to cycle the gear up and down. The handle
now will not go to the up position. It jams about
3/4 of the way to the up position, with the wheel fully
up in the wheel well. When I pull the handle to lower
the gear, the handle locks down, and the wheel lowers
but it will not lock down. If I put any force on the
wheel it collapses again.

I first thought the gas strut/spring was bad, so I
spent considerable time taking it out. It seems to
be working OK. The gas spring is about 5.9' long and
has about a 1.5' stroke. I can close it with about
20 or more pounds of force, and then it springs back
to the full extended position. So it functions OK.
But -- maybe the gas strut has lost some pressure
and should have a higher force?

I carefully took a mirror and flashlight and carefully
inspected every linkage, rod, crack, shaft, weld, and
rivet in the landing gear system for signs of damage.
Everything looks normal. The only thing that looks
abnormal is the angle of the arms coming off the shock/isolation
mounts on the rear of the wheel well wall.

Any ideas on what broke? How to fix it?

Mike

[Andrew Warbrick]

I think you might want to take a look at this

http://212.8.200.175/~techdg/ls-tm/tm_LS6/TM6012.pdf

It's a mandatory modification to replace the gas strut
with an aluminium bar.

I should also get an inspector to have a good look
at the mechanism in case anything got bent when it
collapsed.

As you're probably missing this mandatory modification
you might want to have a browse through the DG website
and check that all the other ones have been applied
as well.

Regards,

Andrew Warbrick

At 01:12 01 June 2004, Michael Higgins wrote:
>My LS-6 gear collapsed and now will not lock down or
>up. Has any other LS-6 drivers had this happen? What's
>the fix?
>
>I had the glider on the trailer cradle for assembly
>and lowered the gear. I think the cradle was a little
>too low and the gear contacted the ground prior to
>the mechanism locking fully down. I didn't know that
>it wasn't locked and pushed the handle to the locked
>position. The gas strut retracted and allowed the
>handle to lock down, without the gear being actually
>locked. When I pushed the glider off the cradle, the
>gear collapsed. When collapsed on the ground, the handle
>was still in the locked-down position.
>
>With plenty of help, I put the glider back on the cradle
>and then tried to cycle the gear up and down. The handle
>now will not go to the up position. It jams about
>3/4 of the way to the up position, with the wheel fully
>up in the wheel well. When I pull the handle to lower
>the gear, the handle locks down, and the wheel lowers
>but it will not lock down. If I put any force on the
>wheel it collapses again.
>
>I first thought the gas strut/spring was bad, so I
>spent considerable time taking it out. It seems to
>be working OK. The gas spring is about 5.9' long and
>has about a 1.5' stroke. I can close it with about
>20 or more pounds of force, and then it springs back
>to the full extended position. So it functions OK.
> But -- maybe the gas strut has lost some pressure
>and should have a higher force?
>
>I carefully took a mirror and flashlight and carefully
>inspected every linkage, rod, crack, shaft, weld, and
>rivet in the landing gear system for signs of damage.
> Everything looks normal. The only thing that looks
>abnormal is the angle of the arms coming off the shock/isolation
>mounts on the rear of the wheel well wall.
>
>Any ideas on what broke? How to fix it?
>
>Mike
>
>
>

[JJ Sinclair]

Mike,
There are 2 gas struts on the 6, one on the gear and another in the linkage on
the left side (?) that is almost impossible to see or to get to. This is the
one that should be replaced with an aluminum bar. If the handle and gear
positions, don't agree, something is bent. Check the drive arm at the gear box.

The last time I saw your problem (fuselage not high enough when lowering the
gear) the gear collapsed on take off.

Good luck, JJ

BTW, you 3 drivers can check the condition of your gas strut by trying to
collapse the gear by applying forward pressure on the drag links. It should
only move about an inch and then spring right back to over-center. Do this
check with the fuselage in your trailed dolly, please.
JJ Sinclair

[BTIZ]

same thing happened to our LS-4... glider was not high enough in the dolly
to have the tire clear the ground when extended.. so it did not fully extend
although the lever was all the way to the down position.. when it was
rolled/slide off the dolly it went to the belly.

Luckily.. no damage, we had to support the fuselage and remove the wings to
be able to lift it back to the dolly.. had the mech check for damage and
none could be found... re rigged and flew it.. no problems since... check
list item.. be sure the dolly is high enough when the gear is extended that
the tire does not touch the ground.

BT
"Michael Higgins" > wrote in message
...
> My LS-6 gear collapsed and now will not lock down or
> up. Has any other LS-6 drivers had this happen? What's
> the fix?
>
> I had the glider on the trailer cradle for assembly
> and lowered the gear. I think the cradle was a little
> too low and the gear contacted the ground prior to
> the mechanism locking fully down. I didn't know that
> it wasn't locked and pushed the handle to the locked
> position. The gas strut retracted and allowed the
> handle to lock down, without the gear being actually
> locked. When I pushed the glider off the cradle, the
> gear collapsed. When collapsed on the ground, the handle
> was still in the locked-down position.
>
> With plenty of help, I put the glider back on the cradle
> and then tried to cycle the gear up and down. The handle
> now will not go to the up position. It jams about
> 3/4 of the way to the up position, with the wheel fully
> up in the wheel well. When I pull the handle to lower
> the gear, the handle locks down, and the wheel lowers
> but it will not lock down. If I put any force on the
> wheel it collapses again.
>
> I first thought the gas strut/spring was bad, so I
> spent considerable time taking it out. It seems to
> be working OK. The gas spring is about 5.9' long and
> has about a 1.5' stroke. I can close it with about
> 20 or more pounds of force, and then it springs back
> to the full extended position. So it functions OK.
> But -- maybe the gas strut has lost some pressure
> and should have a higher force?
>
> I carefully took a mirror and flashlight and carefully
> inspected every linkage, rod, crack, shaft, weld, and
> rivet in the landing gear system for signs of damage.
> Everything looks normal. The only thing that looks
> abnormal is the angle of the arms coming off the shock/isolation
> mounts on the rear of the wheel well wall.
>
> Any ideas on what broke? How to fix it?
>
> Mike
>
>

[David Kinsell]

"Michael Higgins" > wrote in message ...
>
> I first thought the gas strut/spring was bad, so I
> spent considerable time taking it out. It seems to
> be working OK. The gas spring is about 5.9' long and
> has about a 1.5' stroke. I can close it with about
> 20 or more pounds of force, and then it springs back
> to the full extended position. So it functions OK.
> But -- maybe the gas strut has lost some pressure
> and should have a higher force?

Struts like that should take something like 80 pounds force
to compress them, so I expect it's old. The bad news is
that a weak strut won't prohibit the handle from going to the
up position like you're seeing, so that's not the immediate
problem. The second "strut" on the gear is an oil-filled damper,
not pressurized at all. They leak over the years and also need
to be replaced, but again that's not the problem you're looking
at.


>
> I carefully took a mirror and flashlight and carefully
> inspected every linkage, rod, crack, shaft, weld, and
> rivet in the landing gear system for signs of damage.
> Everything looks normal. The only thing that looks
> abnormal is the angle of the arms coming off the shock/isolation
> mounts on the rear of the wheel well wall.
>
> Any ideas on what broke? How to fix it?
>

Don't know. Every case of gear collapse I've heard of due
to the wheel not being fully deployed was resolved without
permanent damage, outside of maybe gear doors.

-Dave

[Chip Bearden]

I owned an LS-3, not an LS-6, but I understand there are many common
elements. My experience is the same as Dave's, below. The second strut
mounted inside the gear box near the wheel is a damper, not a gas
spring. The gas spring in my LS-3 was rated, as I recall, for about 90
lbs. when new and typically declined to about half of that over time.
While a weak gas spring (and an old damper--look up my postings on
this subject from a few years ago) can certainly contribute to a gear
collapse, I don't know of any reason why you'd be more or less likely
to suffer permanent damage. I, too, know of no other incidents where
anything like this happened and I know of a lot of LS "self
retracting" landing gears over the years (including mine on two
occasions).

So long as you're looking for other problems, however, the rubber
shock mounts can deteriorate (again, assuming that the '3 and the '6
are similar). The bond between the rubber donut sandwiched between
inner and outer steel bushings can fail over time, especially if the
ship has been left assembled for extended periods, whether inside
or--horrors--outside. If so, the "resting" angle/geometry of the upper
struts would tend to change and might cause the kind of situation you
describe. Said shock mounts were relatively easy to replace in my LS-3
(1/2 day with someone else helping me) but I don't know if the same
thing is true for the LS-6. The classic indicator of a failing shock
mount was that the fuselage sat somewhat lower to the ground when the
ship was rigged. There was no other outward indication that anything
was wrong, even after removing the old mounts (you'd have to torque
them somehow and compare new to old values). Might be worth
investigating if you can't find anything else.

Chip Bearden

"David Kinsell" > wrote in message news:<Kykvc.31762$IB.27403@attbi_s04>...
> "Michael Higgins" > wrote in message ...
> >
> > I first thought the gas strut/spring was bad, so I
> > spent considerable time taking it out. It seems to
> > be working OK. The gas spring is about 5.9' long and
> > has about a 1.5' stroke. I can close it with about
> > 20 or more pounds of force, and then it springs back
> > to the full extended position. So it functions OK.
> > But -- maybe the gas strut has lost some pressure
> > and should have a higher force?
>
> Struts like that should take something like 80 pounds force
> to compress them, so I expect it's old. The bad news is
> that a weak strut won't prohibit the handle from going to the
> up position like you're seeing, so that's not the immediate
> problem. The second "strut" on the gear is an oil-filled damper,
> not pressurized at all. They leak over the years and also need
> to be replaced, but again that's not the problem you're looking
> at.
>
>
> >
> > I carefully took a mirror and flashlight and carefully
> > inspected every linkage, rod, crack, shaft, weld, and
> > rivet in the landing gear system for signs of damage.
> > Everything looks normal. The only thing that looks
> > abnormal is the angle of the arms coming off the shock/isolation
> > mounts on the rear of the wheel well wall.
> >
> > Any ideas on what broke? How to fix it?
> >
>
> Don't know. Every case of gear collapse I've heard of due
> to the wheel not being fully deployed was resolved without
> permanent damage, outside of maybe gear doors.
>
> -Dave