LS-6a Landing Gear Problem

"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

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