And just for clarification.... My comment regarding VEP switches was specific to the hydraulic pressure switches. I forgot that the pitot pressure switch was also made by VEP. The hydraulic switch replacements are something around $70.
Chris Zavatson N91CZ 360std 1,400 hrs
Just went through that problem on my Legacy; VEP switch prevented retraction; checked out perfectly on the ground, regularly malfunctioned if flight. I polled the LML and got several great inputs; selected the TCW ASW-1, available for $45 from Aircraft Spruce (vs $380 quote from Lancair for the VEP). It's much smaller, lighter, easy to calibrate, and so far, is working perfectly.
On Jan 30, 2013, at 11:30 AM, Gary Edwards wrote:
Rob,
Most likely the original VEP switches will be internally corroided and not
usuable if they have never been put into service. I went thru that
situation years ago (1990's) during the extended build time. It cost a
fortune to have the VEP company even just test them them, more than a new set
from Lancair would cost for the new style. And the new style is install
and fly, whereas the VEP's require adjustments during new flight hours, a big
inconvenience.
Gary Edwards
LNC2
Sent: Wednesday, January 30, 2013 5:28
AM
Subject: [LML] Re: Thermal influence on
Hydraulic Pressure
Rob,
Lancair carries a new type that is much more reliable. I
forget the brand name.
Chris Zavatson
N91CZ
360std 1,400 hrs
Chris,
I
am interested in your comment about the “Old VEP pressure switches”. The 360
kit I am building comes with those pressure switches. What do you recommend we
should use in place of them?
Thanks
again.
Rob
Stevens
Perth,
Western
Australia.
From:
Lancair Mailing List [mailto:lml@lancaironline.net] On Behalf Of Chris
Zavatson
Sent: Tuesday, 29 January 2013 11:56 PM
To:
lml@lancaironline.net
Subject: [LML] Re: Thermal influence on
Hydraulic Pressure
Yep, the failure
modes are completely unrelated to each other.
There is a second
failure-to-retract mode. In fact, it is the only one I experienced in my
plane. It was with the old VEP pressure switches. They would stick
open on occassion. Then the problem is not too much pressure, it is not
having any.
Failure to retract
can be a bit more serious if in IMC or taking off at high density
altitude.
The failure to extend
can be fixed by simply raising the operating pressure of the low side
circuit.
I have looked at
pumps spanning the 95 to 2011 manufacturing time frame. The only one
that would lock up on the ground had spool return springs. Since the 70g
rattle-your-spool controversy appeared, I have also been measuring the spool
resistance in every pump I get my hands on. -haven't found an
outliers yet, but I will keep looking.
While
waiting for Wolfgang's answer, some 200/300 series pilots are becoming
concerned that they can't get the gear down when needed. First, Lorn's
secondary problem is that he didn't look for the "gear down and locked" lights
before landing. While the gear down pressure switch saw enough
pressure to not allow the pump to start, the failure to recognize that
the gear was not down contributed to the belly in landing.
To
allow people to be more comfortable about the hydro-electric system they
should be reminded of this
1.
The failure to RETRACT the gear because of high pressure on both sides is
a problem because of the safe design. Opening the dump valve
doesn't resolve the problem because the system is in a static state with
the gear down and locked. There are no physical forces able to
change the system condition - no G-maneuvers, no slips or skids,
nada.
|