Ian,
I’m
not familiar with the term “circlip” but I assume you’re talking about the
snap rings, right?
I
strongly recommend reading the information on Chris Zavatson’s site (http://www.n91cz.com/) regarding the LNC2
hydraulic system. He provides
valuable insight into the system and its pitfalls. He also has several videos at http://www.n91cz.com/Hydraulics/Lancair_Hydraulics.htm
that have proven very beneficial to me and others when this system presents
issues. I learned a great deal
from him supplemented by my own research, tearing into the system, rebuilding
my pump and all of my cylinders.
It
certainly sounds like you’ve isolated the troublesome cylinder. When you took it apart did you see any
noticeably damaged O-rings? A
damaged O-ring would indicate a possible burr or roughness that should be
resolved.
Are
you getting adequate pressure?
You should have no less than about 500 psi on the low side and about
1200 psi on the high side. Even
so, you should adjust it to about 700/1500 psi
respectively.
I
don’t know of a shop in my area (Washington, DC) but I haven’t looked for one
either. But I’m sure any decent
shop should be able to rebuild and test it. Just don’t tell them it’s for an
airplane. I believe these
cylinders were originally designed for raising and lowering outboard boat
engines so check with a boat shop in your area.
I
have two spares in my inventory if you’d like to have one but they’re
untested. I’d recommend replacing
all of the O-rings before installing either one of them just to save
time. Lancair has them new at
$275 USD the last time I checked.
I’ll let you have one for $100 USD but I want your old one in
exchange.
Good
luck and let me know if you want one of my
spares.
Danny
LNC2-360
N
38° 43' 25.7"
W
77° 30' 38.6"
Nothing
is foolproof to a sufficiently talented
fool.
From:
Ian Crowe [mailto:ian.crowe@sympatico.ca]
Sent: Thursday, October 18, 2012 12:41
PM
To:
lml@lancaironline.net
Subject: [LML] Re: Hydraulic cylinder
main gear Lancair 320
No I did
not hone and deburr the cylinders. I have no tool to easily do that and
indeed saw no need unless in the way of the circlip
grooves.
Would the
pump experience a leak across the shuttle valve if it was going to leak and
how would you test for that?
Once we
blanked off the offending cylinder by a process of elimination the pressure
loss stopped. I have gauges on the HP and LP sides to help
me.
I too
thought the repair was easy and have done more than few in my time but
this one is a little perplexing!
Do you
know of a good hydraulic shop near you who would repair and test the
cylinder?
-----
Original Message -----
Sent:
Tuesday, October 09, 2012 8:06 AM
Subject:
[LML] Re: Hydraulic cylinder main gear Lancair
320
I’m
not. I’m just saying they’re
easy to repair. When you
replaced the seals did you hone & deburr the cylinder? Have you checked the pump for an
internal leak?
Danny
LNC2-360,
650 hours
N
38° 43' 25.7"
W
77° 30' 38.6"
Didn't
know you were in the cylinder repair business!! It is the actuating
cylinder that is giving the problem. I have rebuilt it twice and it
lasts for a while and then starts to leak again across the piston. No
sign of any other leaks anywhere and we have blanked off all the other
cylinders and the pump still cycles. So it must be the cylinder.
I have
actually sold the plane to my flying buddy who did all the initial flight
testing for me but am helping him with the maintenance now and
again
-----
Original Message -----
Sent:
Sunday, October 07, 2012 6:15 PM
Subject:
[LML] Re: Hydraulic cylinder main gear Lancair
320
Ian,
Are
you looking for an actuating (gear up & down) cylinder or an oleo
suspension (Ong debonger type) cylinder? I have actuating cylinders that
can be rebuilt and I’ll even do it for you. I have no oleo struts but if yours
need to be rebuilt I’m sure it can’t be
difficult.
Danny
LNC2-360,
650 hours
N
38° 43' 25.7"
W
77° 30' 38.6"
Does
any one have a spare main gear cylinder for sale?
Does
anyone know where they can be repaired successfully or failing that where
new ones can be bought?