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After multiple conversations with the product manager of the Oildyne pump and Lancair, it has been concluded that the thermal lock-up was overlooked during the most recent design change (~2005). Parker/Oildyne has since been supplying parts free of charge to fix the oversight. I have several sets in case anyone needs some. Chris Zavatson N91CZ 360std 1,400 hrs
From: Wolfgang <Wolfgang@MiCom.net>
To: lml@lancaironline.net
Sent: Tuesday, January 29, 2013 8:11 AM
Subject: [LML] Re: Thermal influence on Hydraulic Pressure
After multiple conversations with the product
manager of the Oildyne pump, it has been concluded (no, I have not tested with
every version of the pump ever made) that simply running the pump in the
appropriate direction will accomplish the desired action, sending the spool to
the required position, regardless of the version. The module has
been tested with the standard published Lancair 300 series hydraulic
system. Thermal lock was simulated by closing the pressure switches as
needed. I include a similar test procedure with the module. There are
multiple units in the field.
Wolfgang
----- Original Message -----
Sent: Monday, January 28, 2013 2:48
PM
Subject: Thermal influence on Hydraulic
Pressure
Wolfgang,
Two
questions. Have you tested your Module under Thermal Lock with all the
configurations of hydraulic systems and pump variations supplied for Lancairs
over the years? Which Lancair are you flying or
building?
Steve
Colwell Legacy
From: Lancair Mailing
List [mailto:lml@lancaironline.net] On Behalf Of
Wolfgang
Sent: Monday, January 28, 2013 11:01 AM
To:
lml@lancaironline.net
Subject: [LML] Re: Thermal influence on
Hydraulic Pressure
Understood . . .
but a module like mine doesn't care what version your pump is, it just
works.
----- Original
Message -----
Sent: Sunday, January
27, 2013 6:59 AM
Subject: Re: [LML] Re:
Thermal influence on Hydraulic Pressure
Lancair started
adding return springs inside the spool valve for Legacy pumps in about
2005. One of the consequences of doing this is what you have observed
in the hangar. You sort of have a 'get out of jail free' card in that
your hydraulic system has a three-way valve. It doesn't prevent the
lock-up. It just gives you a way out. Folks installing the
'Legacy' pump in 300 series plane with a two-way valve can get stuck.
Fortunately the springs are easily removed and Parker has been providing the
parts free-of-charge to reset pumps back to the pre-2005 configuration.
This
has happened to me even at the beginning of a flight, if the temps in the
hangar have gone from cold on a previous day, to warm on flight day. I
guess cold temps shrink the fluid and suck more from the reservoir into the
lines, and when it warms, the pressure builds on both sides of the system,
so that the "up" and "down" pressure switches are both open and the gear
won't move until I pop the bleed valve.
Nasty when the gear won't retract just after blasting
off into a low overcast.
On
Jan 25, 2013, at 7:23 AM, randy snarr
wrote:
. I dont like having to open the dump valve but it is
necessary once in a while especially when it is cold. The pressures on both
sides of the system climb due to the engine heat and the gear sometimes will
not move without dumping the
pressure.
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