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Practicing Gear Down in Flight without Hand
Pump
Slight Change of Thread:
How many pilots are testing the nose gear down in flight in the
absence of any hydralic pressure? After pulling the breaker and
bleeding off hydralic pressure (with flaps), selecting gear down
without hand pump, waiting for nose gear GREEN...are you specifically
observing for this?
Of course, I have practiced hand pump gear down emergency
procedure in flight, but I do not recall waiting and observing the
nose gear green light coming on before grabbing the hand pump.
As Charlie says, this would be an important annual demonstration of
the over center gas spring on the nose gear.
I recall some people have trepidation about shutting down the
engine and practicing best glide in coarse pitch. Not quite the
same, but still an in flight demonstrated practice failure.
Jeff L
LIVP
Hi Bob,
I think if you'll look
LIV hydraulic schematic over, you will see that -- the shuttle valve
determines which pressure source to use. If the electric hydraulic
pump is inoperative--then the hand pump will provide enough pressure
to extend the main landing gears provided the system is
intact.
Any leak after the gear
selector will dump all (electric or hand pump--in the down position)
hydraulic pressure. That is why the designers of this system installed
the nose gear gas spring.
Anything after the gear
selector-- well render the hydraulics inoperative. Including the hand
pump. That is why the designer put a gas spring to extend the nose
gear. To save our wallets.
Charlie K.
See me on the web at
www.Lancair-IV.com
From: "marv@lancair.net"
<marv@lancair.net>
To: lml@yahoo.com
Sent: Tue, February 16, 2010 9:10:13 AM
Subject: [LML] Re: Turbine IVP Landing Accident
Video
Posted for "Robert Pastusek"
<rpastusek@htii.com>:
Laurie,
First of all, a very nice job of taking care of this emergency! Also,
thanks
so much for the report to the rest of us. As you note, these
things always
provide useful information, and this one caused me to think
again about my
own airplane. Most of my IV-P electrical system is protected
with fuses; the
alternators and hydraulic pump being the exceptions, and with
the CB's for
these made very readily accessible for just the situation you
encountered.
My concern is that you didn't have sufficient hydraulic fluid to
lower/lock
the gear with the manual pump. I determined during construction
that the
pickup tube for the manual pump extended lower in the tank than
the electric
pump pickup, and just let it go at that. I did not test this at
all.
If you have any thoughts about why you didn't have enough fluid
left to use
the backup system, I'd be most appreciative. Could the pitch
attitude of the
aircraft had an effect? Other thoughts? Based on your
experience, I'm
thinking of draining down my system through the electric pump
and then
trying the manual pump. Like I said, I took this one on faith of
the
designer and did not test it, although it would have been easy
to do during
build.
Again, nice job landing the aircraft, and I'm happy you
sustained minimal
damage in the process. Thanks especially for your comprehensive
report. If
you find more, especially about why the emergency pump didn't
work, we'd all
appreciate hearing.
Bob Pastusek
For LOBO
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