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1. 08:05 AM - Re: wtb oildyne pump (Bruce Gray)
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| Subject: | wtb oildyne pump |
Careful attention should be placed on testing the emergency down
pump/system
when the aircraft is on jacks. If you didn't know, the GIII has
mechanical
uplocks on all 3 gear legs and if hydraulic pressure is lost, they WILL
NOT
free fall. The nose gear uplock is held in place, against spring
pressure,
by hydraulic pressure. When up pressure is lost by a leak or turning the
dump valve, a spring pulls the uplock open and the nose gear will drop.
Hydraulic pressure in the down cylinders from the hand pump is required
to
unlock the mains.
In the older system, without the separate down cylinders, there were
some
failure modes that left you with no way to lower the mains. Some
builders
went so far as to install CO2 blowdown systems or run a manual cable
from
the uplock lever to the cockpit to allow manual release.
These issues were resolved in the latest gear system, where the only
commonality with the normal extension system is the reserve canister.
Bruce
<http://www.glasair.org/> www.Glasair.org
-----Original Message-----
From: owner-glasair-list-server@matronics.com
[mailto:owner-glasair-list-server@matronics.com] On Behalf Of
darnpilot@aol.com
Sent: Friday, May 09, 2008 12:23 PM
Subject: Re: Glasair-List: wtb oildyne pump
Ah, thank you Bruce. A light went off when you explained the
differences.
Mine is (I think) correct. See photo. So the bottom fitting is for the
emergency pump. Now I see the logic. If the electric pump fails or
loses
fluid, the emergency system can use all that extra fluid in the canister
to
pump down the gear. Clever.
Jeff
<http://pictures.aol.com/ap/singleImage.do?pid=4ab0Csr-zxngtxXIflvcoRcF
jut6L
lpD5KRzv4xQp5Fd3Ig%3D>
View full size
-----Original Message-----
From: Bruce Gray <Bruce@glasair.org>
Sent: Fri, 9 May 2008 11:56 am
Subject: RE: Glasair-List: wtb oildyne pump
There are 2 ports on the canister. The top one is the fluid return, when
you
open the dump valve, this is where the fluid goes. The bottom one is the
pickup for the emergency hand pump. Yours should be plumbed this way. If
it's not then it's wrong. The separate cylinders for the emergency down
system were only in the latest iteration of the gear system. Prior to
this,
the system used the normal cylinders for emergency extension. With the
latest gear the output of the hand pump was redirected to the new
emergency
down cylinders via independent lines. The return line and pickup point
of
the hand pump to the canister did not change.
Bruce
<http://www.glasair.org/> www.Glasair.org
-----Original Message-----
From: owner-glasair-list-server@matronics.com
[mailto:owner-glasair-list-server@matronics.com
<mailto:owner-glasair-list-server@matronics.com?> ] On Behalf Of
darnpilot@aol.com
Sent: Friday, May 09, 2008 11:38 AM
Subject: Re: Glasair-List: wtb oildyne pump
That may be the way the system works on an airplane with the separate
hydraulic down cylinders for the emergency extension, but not on the
others.
In my plane the hand pump and release valve is the "emergency system".
The
way the system is plumbed, there is no way to access all the fluid below
the
pump pickup in the canister, and in my case, its quite a lot. Are you
saying the plumbing is different, i.e., different pickups from the pump
canister for the emergency down system?
Just trying to understand.
Jeff
-----Original Message-----
From: Bruce Gray <Bruce@glasair.org>
Sent: Fri, 9 May 2008 11:19 am
Subject: RE: Glasair-List: wtb oildyne pump
The ports on the canister are installed by Glasair Aviation. The left
over
portion at the bottom of the can is the fluid reserve used by the
emergency
gear extension system.
Bruce
<http://www.glasair.org/> www.Glasair.org
-----Original Message-----
From: owner-glasair-list-server@matronics.com
[mailto:owner-glasair-list-server@matronics.com
<mailto:owner-glasair-list-server@matronics.com?> ] On Behalf Of
darnpilot@aol.com
Sent: Friday, May 09, 2008 8:06 AM
Subject: Re: Glasair-List: wtb oildyne pump
Bruce:
I did not know that the hydraulic reservoir was proprietary. That said,
why
is the canister unique? When I serviced the pump on my Glasair III I
found
that the reservoir held a lot more fluid than the pickups could access,
i.e., the pickup only went an inch or two down into a reservoir leaving
about 4 inches inaccessible. Is there some logic behind this
"proprietary"
design? Why cannot a non-proprietary canister/reservoir work as well?
It
is not a question of cost, more of why?
Thanks.
Jeff
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